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Eclipse 工具上Springboot项目的简单增删改查的搭建

發布時間：2024/1/8 javascript 29 豆豆

生活随笔收集整理的這篇文章主要介紹了 Eclipse 工具上Springboot项目的简单增删改查的搭建小編覺得挺不錯的,現在分享給大家,幫大家做個參考.

一、為嘛子要學習Springboot

二、簡單的說下springboot

三、咱們對比看看唄

四、開始操作，建項目

1、建一個maven項目

2、pom.xml 依賴以及配置文件

①簡單的依賴如下，我就不細說了

②配置文件，application.yml

3、創建相應的包結構

4、使用?Mybatis Generator 自動生成實體類、mapper和mapper.xml文件

5、填寫各個包的內容

①mapper? 增加一個方法

②mapper.xml 的寫法

③service 層接口的編寫

④service 的 Impl 實現類

⑤Controller 層

五、運行

六、遇到的問題以及解決方案

1、剛建好項目，啥都沒干呢就看到 index.jsp 紅叉，如下：

錯誤狀況：

?解決方案：

2、項目基本寫完，沒看到紅叉之類的錯誤提示，但是一運行，報錯

錯誤狀況：

小小分析：

解決方案：

3、再次運行，又報錯了，

錯誤狀況：

查找問題：

定位到問題發生位置后，百度解決：

4、Application run failed 啟動失敗

?小小分析：

解決方案：

5、啟動已經沒問題，但是控制臺有一個警告

警告詳情：

問題所在：

解決問題：

一、為嘛子要學習Springboot

Springboot已經成為基本技能要求的基本。我不知道這樣說語言能通不，只是看到現在各種招聘什么的，基本要求都是分布式、微服務、springboot、springcloud、redis、消息中間件等。就算有的招聘上還寫的SSM等，到時候面試的時候問用過什么框架啥的。問完，你只用過ssm或ssh，他也會問你對于springboot、springcloud等是否有經驗。很多地方，一聽，不會cloud基本就pass掉你。所以，看起來springcloud已經成為必會的基本技能，而學習springcloud，你就拋不開springboot的使用，畢竟springboot建立項目確實快。

二、簡單的說下springboot

????????簡單粗暴的說，springboot就是讓你建項目和使用插件等簡單很多很多，讓你更快更便捷的建立一個項目，減少你在配置上浪費的時間。

????????打個比方，就像你要吃飯，過去的吃飯，就得準備各種食材調料，按一定的順序或者說手法等去處理和調配他們，讓他們成為能夠下咽的幾個菜。而springboot就像你有點錢了，下館子了，去到飯店，一看菜單，嗯~有套餐，就給服務員說，來個AAA套餐，你不用說要什么菜，也不需要知道這些菜有什么食材和調料。反正付了錢直接吃就是了。

????????約定大于配置，化繁為簡，他把很多東西都給你弄好了，有默認的一套，你用就行了。

? ? ? ? 當然嘍，springboot可不止這一個特點，它可以熱部署、內嵌Servlet容器、自動裝配、自帶應用監控等等，對于學霸或者說有上進心的人來說，這些都要去了解，不過我這種渣渣，當然主要是咋個用嘍。

三、咱們對比看看唄

咱們先看下以前的ssm項目，

?看到這么多的 .xml 文件有沒有很開心？開心到想砸了眼前的東西

好像說了很多廢話，還是開始建項目吧

四、開始操作，建項目

聽說eclipse有創建Springboot的插件sts。我沒裝，所以還是maven創建吧

1、建一個maven項目

File→New→Maven Project

直接Next

選擇webapp

?填寫下圖剪頭指示的框框，然后Finish

創建好了，項目結構如下圖

?此時為空的maven項目，我們先把pom.xml引用了好依賴，再在相應的包在 src/main/java 中建好

2、pom.xml 依賴以及配置文件

①簡單的依賴如下，我就不細說了

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.lx</groupId><artifactId>springboot_demo</artifactId><packaging>war</packaging><version>0.0.1-SNAPSHOT</version><name>springboot_demo Maven Webapp</name><url>http://maven.apache.org</url><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.3.1.RELEASE</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.1.3</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.2.6</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId></dependency><dependency><groupId>org.mybatis.generator</groupId><artifactId>mybatis-generator-core</artifactId><version>1.3.5</version></dependency></dependencies><build><finalName>springboot_demo</finalName><resources><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.yml</include><include>**/*.xml</include></includes></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.yml</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></plugin><plugin><groupId>org.mybatis.generator</groupId><artifactId>mybatis-generator-maven-plugin</artifactId><version>1.3.5</version><configuration><verbose>true</verbose><overwrite>true</overwrite></configuration></plugin></plugins></build> </project>

②配置文件，application.yml

server:port: 8080 spring:datasource:#驅動driver-class-name: com.mysql.jdbc.Driverurl: jdbc:mysql://xxx.xxx.xxx.xxx:3306/xxxxxx?characterEncoding=utf8username: rootpassword: *********#連接池類型type: com.alibaba.druid.pool.DruidDataSourcedruid:# 最小數min-idle: 5# 最大數max-active: 20# 初始大小initial-size: 5# 配置獲取連接等待超時時間max-wait: 6000# 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒time-between-eviction-runs-millis: 60000# 配置一個連接在池中最小生存時間單位為毫秒min-evictable-idle-time-millis: 300000validation-query: SELECT 1 FROM DUALtest-while-idle: truetest-on-borrow: falsetest-on-return: false# 打開 PSCache，并且指定每個連接上PSCache的大小pool-prepared-statements: truemax-pool-prepared-statement-per-connection-size: 20# 配置監控統計攔截的filters，去掉后監控界面sql無法統計，wall用于防火墻filters: stat,wallmybatis:# model的包type-aliases-package: com.lx.springboot_demo.modelconfiguration:# 開啟駝峰uName自動映射到u_namemap-underscore-to-camel-case: true# 該配置項配置了MyBatis配置文件保存路徑mapper-locations: classpath:mappers/*.xml # 配置掃描對應實體所在包,將mapper的實現類注入容器我們在啟動器類上加了@MapperScan注解這里就不需要了

3、創建相應的包結構

選擇?src/main/java 反鍵 New → Package

填寫Name 然后完成

把這個Java文件改為啟動類

名字看你自己哦，我這是?Application

修改內容如下：

?重復上面創建包的操作，把需要的包都建好，如下圖：

4、使用?Mybatis Generator 自動生成實體類、mapper和mapper.xml文件

請參考文章? 鏈接：https://blog.csdn.net/qq_39688441/article/details/123851515

5、填寫各個包的內容

由于生成的一套，除了基本的，其他沒有，實際使用還得自己來根據實際情況編寫

①mapper? 增加一個方法

mapper 里就是數據庫操作的方法

?這里簡單，只要定好? 返回值類型、方法名和參數? 就OK啦

②mapper.xml 的寫法

?如上圖，1 為編寫的返回值類型，即為，這個返回值要返回哪些字段

2 為引用的返回值的id

?如上圖，可以把常用的一段sql 提出來，

在需要用到的地方 include 進去

?如上圖為具體的拼寫sql

③service 層接口的編寫

這層也很好寫，想好要干的事，定好服務名、返回參數和入參

④service 的 Impl 實現類

?注意 class 類前面要 @Service 聲明這是業務層組件

這里就是寫業務邏輯，一個業務要干什么，一個業務也會調多個數據庫操作，我這里就簡單調用一個查詢

⑤Controller 層

?到這里，基本上就寫完了

五、運行

運行步驟如下

打開?Application.Java 文件，文件中點擊反鍵，Run As...??→? Java?Application

啟動成功后：

http://localhost:8080/boot/getUserByNickname

http://localhost:8080/boot/getUserByNickname?name=lz

實際上剛建好時? 一運行就報錯，具體狀況請看下面? ?六、2、3、4、5、

六、遇到的問題以及解決方案

1、剛建好項目，啥都沒干呢就看到 index.jsp 紅叉，如下：

錯誤狀況：

剛建完maven項目，一看紅X，趕緊進去看了下

打開index.jsp后，如下問題

?解決方案：

反鍵 Build Path 里?

Jave Build Path 里選擇如下圖紅框?

選擇合適的tomcat

應用并關閉，很快就運行好了

?報錯已經解決

2、項目基本寫完，沒看到紅叉之類的錯誤提示，但是一運行，報錯

錯誤狀況：

具體報錯如下，我貼出來：

14:36:01.267 [main] DEBUG org.springframework.boot.context.logging.ClasspathLoggingApplicationListener - Application failed to start with classpath: [file:/D:/jdk1.8.0_101/jre/lib/resources.jar, file:/D:/jdk1.8.0_101/jre/lib/rt.jar, file:/D:/jdk1.8.0_101/jre/lib/jsse.jar, file:/D:/jdk1.8.0_101/jre/lib/jce.jar, file:/D:/jdk1.8.0_101/jre/lib/charsets.jar, file:/D:/jdk1.8.0_101/jre/lib/jfr.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/access-bridge-64.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/cldrdata.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/dnsns.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/jaccess.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/jfxrt.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/localedata.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/nashorn.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunec.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunjce_provider.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunmscapi.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunpkcs11.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/zipfs.jar, file:/D:/Work/springboot_demo/target/classes/, file:/D:/tomcat/apache-tomcat-9.0.60/lib/annotations-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-ant.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-ha.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-ssi.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-storeconfig.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-tribes.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/ecj-4.20.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/el-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jasper-el.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jasper.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jaspic-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jsp-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/servlet-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-coyote.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-dbcp.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-cs.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-de.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-es.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-fr.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-ja.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-ko.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-pt-BR.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-ru.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-zh-CN.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-jdbc.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-jni.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-util-scan.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-util.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-websocket.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/websocket-api.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-web/2.3.1.RELEASE/spring-boot-starter-web-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter/2.3.1.RELEASE/spring-boot-starter-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot/2.3.1.RELEASE/spring-boot-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.3.1.RELEASE/spring-boot-autoconfigure-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-logging/2.3.1.RELEASE/spring-boot-starter-logging-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar, file:/C:/Users/397004497/.m2/repository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar, file:/C:/Users/397004497/.m2/repository/org/apache/logging/log4j/log4j-to-slf4j/2.13.3/log4j-to-slf4j-2.13.3.jar, file:/C:/Users/397004497/.m2/repository/org/apache/logging/log4j/log4j-api/2.13.3/log4j-api-2.13.3.jar, file:/C:/Users/397004497/.m2/repository/org/slf4j/jul-to-slf4j/1.7.30/jul-to-slf4j-1.7.30.jar, file:/C:/Users/397004497/.m2/repository/jakarta/annotation/jakarta.annotation-api/1.3.5/jakarta.annotation-api-1.3.5.jar, file:/C:/Users/397004497/.m2/repository/org/yaml/snakeyaml/1.26/snakeyaml-1.26.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-json/2.3.1.RELEASE/spring-boot-starter-json-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.11.0/jackson-databind-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/core/jackson-annotations/2.11.0/jackson-annotations-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.11.0/jackson-core-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.11.0/jackson-datatype-jdk8-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.11.0/jackson-datatype-jsr310-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/module/jackson-module-parameter-names/2.11.0/jackson-module-parameter-names-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-tomcat/2.3.1.RELEASE/spring-boot-starter-tomcat-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/apache/tomcat/embed/tomcat-embed-core/9.0.36/tomcat-embed-core-9.0.36.jar, file:/C:/Users/397004497/.m2/repository/org/glassfish/jakarta.el/3.0.3/jakarta.el-3.0.3.jar, file:/C:/Users/397004497/.m2/repository/org/apache/tomcat/embed/tomcat-embed-websocket/9.0.36/tomcat-embed-websocket-9.0.36.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-web/5.2.7.RELEASE/spring-web-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-beans/5.2.7.RELEASE/spring-beans-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-webmvc/5.2.7.RELEASE/spring-webmvc-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-context/5.2.7.RELEASE/spring-context-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-expression/5.2.7.RELEASE/spring-expression-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-data-jpa/2.3.1.RELEASE/spring-boot-starter-data-jpa-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-jdbc/2.3.1.RELEASE/spring-boot-starter-jdbc-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/com/zaxxer/HikariCP/3.4.5/HikariCP-3.4.5.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-jdbc/5.2.7.RELEASE/spring-jdbc-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/jakarta/transaction/jakarta.transaction-api/1.3.3/jakarta.transaction-api-1.3.3.jar, file:/C:/Users/397004497/.m2/repository/jakarta/persistence/jakarta.persistence-api/2.2.3/jakarta.persistence-api-2.2.3.jar, file:/C:/Users/397004497/.m2/repository/org/hibernate/hibernate-core/5.4.17.Final/hibernate-core-5.4.17.Final.jar, file:/C:/Users/397004497/.m2/repository/org/jboss/logging/jboss-logging/3.4.1.Final/jboss-logging-3.4.1.Final.jar, file:/C:/Users/397004497/.m2/repository/org/javassist/javassist/3.24.0-GA/javassist-3.24.0-GA.jar, file:/C:/Users/397004497/.m2/repository/net/bytebuddy/byte-buddy/1.10.11/byte-buddy-1.10.11.jar, file:/C:/Users/397004497/.m2/repository/antlr/antlr/2.7.7/antlr-2.7.7.jar, file:/C:/Users/397004497/.m2/repository/org/jboss/jandex/2.1.3.Final/jandex-2.1.3.Final.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/classmate/1.5.1/classmate-1.5.1.jar, file:/C:/Users/397004497/.m2/repository/org/dom4j/dom4j/2.1.3/dom4j-2.1.3.jar, file:/C:/Users/397004497/.m2/repository/org/hibernate/common/hibernate-commons-annotations/5.1.0.Final/hibernate-commons-annotations-5.1.0.Final.jar, file:/C:/Users/397004497/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.3/jaxb-runtime-2.3.3.jar, file:/C:/Users/397004497/.m2/repository/org/glassfish/jaxb/txw2/2.3.3/txw2-2.3.3.jar, file:/C:/Users/397004497/.m2/repository/com/sun/istack/istack-commons-runtime/3.0.11/istack-commons-runtime-3.0.11.jar, file:/C:/Users/397004497/.m2/repository/com/sun/activation/jakarta.activation/1.2.2/jakarta.activation-1.2.2.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/data/spring-data-jpa/2.3.1.RELEASE/spring-data-jpa-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/data/spring-data-commons/2.3.1.RELEASE/spring-data-commons-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-orm/5.2.7.RELEASE/spring-orm-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-tx/5.2.7.RELEASE/spring-tx-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-aspects/5.2.7.RELEASE/spring-aspects-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/mysql/mysql-connector-java/8.0.20/mysql-connector-java-8.0.20.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/spring/boot/mybatis-spring-boot-starter/2.1.3/mybatis-spring-boot-starter-2.1.3.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/spring/boot/mybatis-spring-boot-autoconfigure/2.1.3/mybatis-spring-boot-autoconfigure-2.1.3.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/mybatis/3.5.5/mybatis-3.5.5.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/mybatis-spring/2.0.5/mybatis-spring-2.0.5.jar, file:/C:/Users/397004497/.m2/repository/jakarta/xml/bind/jakarta.xml.bind-api/2.3.3/jakarta.xml.bind-api-2.3.3.jar, file:/C:/Users/397004497/.m2/repository/jakarta/activation/jakarta.activation-api/1.2.2/jakarta.activation-api-1.2.2.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-core/5.2.7.RELEASE/spring-core-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-jcl/5.2.7.RELEASE/spring-jcl-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/com/alibaba/druid-spring-boot-starter/1.2.6/druid-spring-boot-starter-1.2.6.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-aop/2.3.1.RELEASE/spring-boot-starter-aop-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-aop/5.2.7.RELEASE/spring-aop-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/aspectj/aspectjweaver/1.9.5/aspectjweaver-1.9.5.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/generator/mybatis-generator-core/1.3.5/mybatis-generator-core-1.3.5.jar] 14:36:01.355 [main] ERROR org.springframework.boot.SpringApplication - Application run failed java.lang.IllegalStateException: Failed to load property source from 'file:/D:/Work/springboot_demo/target/classes/application.yml' (classpath:/application.yml)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:554)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.loadForFileExtension(ConfigFileApplicationListener.java:499)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:469)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$null$7(ConfigFileApplicationListener.java:448)at java.lang.Iterable.forEach(Iterable.java:75)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$load$8(ConfigFileApplicationListener.java:448)at java.lang.Iterable.forEach(Iterable.java:75)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:445)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$load$0(ConfigFileApplicationListener.java:348)at org.springframework.boot.context.config.FilteredPropertySource.apply(FilteredPropertySource.java:54)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:336)at org.springframework.boot.context.config.ConfigFileApplicationListener.addPropertySources(ConfigFileApplicationListener.java:226)at org.springframework.boot.context.config.ConfigFileApplicationListener.postProcessEnvironment(ConfigFileApplicationListener.java:210)at org.springframework.boot.context.config.ConfigFileApplicationListener.onApplicationEnvironmentPreparedEvent(ConfigFileApplicationListener.java:200)at org.springframework.boot.context.config.ConfigFileApplicationListener.onApplicationEvent(ConfigFileApplicationListener.java:188)at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:80)at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:345)at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)at com.lx.springboot_demo.Application.main(Application.java:19) Caused by: org.yaml.snakeyaml.scanner.ScannerException: while scanning for the next token found character '\t(TAB)' that cannot start any token. (Do not use \t(TAB) for indentation)in 'reader', line 6, column 3:#驅動^at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:419)at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:227)at org.yaml.snakeyaml.parser.ParserImpl$ParseBlockMappingValue.produce(ParserImpl.java:586)at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:158)at org.yaml.snakeyaml.parser.ParserImpl.checkEvent(ParserImpl.java:148)at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:136)at org.yaml.snakeyaml.composer.Composer.composeValueNode(Composer.java:257)at org.yaml.snakeyaml.composer.Composer.composeMappingChildren(Composer.java:248)at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:236)at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:162)at org.yaml.snakeyaml.composer.Composer.composeValueNode(Composer.java:257)at org.yaml.snakeyaml.composer.Composer.composeMappingChildren(Composer.java:248)at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:236)at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:162)at org.yaml.snakeyaml.composer.Composer.getNode(Composer.java:95)at org.yaml.snakeyaml.constructor.BaseConstructor.getData(BaseConstructor.java:134)at org.yaml.snakeyaml.Yaml$1.next(Yaml.java:494)at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:200)at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:164)at org.springframework.boot.env.OriginTrackedYamlLoader.load(OriginTrackedYamlLoader.java:76)at org.springframework.boot.env.YamlPropertySourceLoader.load(YamlPropertySourceLoader.java:50)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.loadDocuments(ConfigFileApplicationListener.java:608)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:524)... 25 common frames omitted

小小分析：

首先找到最開始報錯的地方，

java.lang.IllegalStateException: Failed to load property source from 'file:/D:/Work/springboot_demo/target/classes/application.yml' (classpath:/application.yml)

Failed to load property source from ‘file:/xxxxxxxxxxxxxx.xxxxx.yml’??(classpath:/application.yml)

這個是說你的yml有問題，可能是語法有錯

咋們往下翻：

?這就是提示了

打開? yml? 文件

?看到了嗎，和上面提示的一樣，第6行，第3個位置開始的? “#驅動”

我這里，一看，這個中文注釋是這個文件的第一個中文注釋

所以我猜是注釋有問題

解決方案：

把? yml? 文件里所有注釋全部刪掉

3、再次運行，又報錯了，

錯誤狀況：

2022-04-02 16:03:36.377 ERROR 24484 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : 在路徑為的上下文中，Servlet[dispatcherServlet]的Servlet.service（）引發了具有根本原因的異常Request processing failed; nested exception is java.lang.NullPointerExceptionjava.lang.NullPointerException: nullat com.lx.springboot_demo.controller.UserMainController.getUserByNickname(UserMainController.java:22) ~[classes/:na]at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_101]at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_101]at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_101]at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_101]at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]

查找問題：

通過打印語句，發現，?Controller 層已經進入，沒進??Service? 層，

檢查注解，發現??Controller 層用?Service? 時，忘了注入了

?加上自動注入

?進入到service層打印，但是又報錯

2022-04-02 16:08:46.374 ERROR 23972 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : 在路徑為的上下文中，Servlet[dispatcherServlet]的Servlet.service（）引發了具有根本原因的異常Request processing failed; nested exception is java.lang.IllegalArgumentException: Result Maps collection does not contain value for com.lx.springboot_demo.dao.UserMainMapper.Listjava.lang.IllegalArgumentException: Result Maps collection does not contain value for com.lx.springboot_demo.dao.UserMainMapper.Listat org.apache.ibatis.session.Configuration$StrictMap.get(Configuration.java:1009) ~[mybatis-3.5.5.jar:3.5.5]at org.apache.ibatis.session.Configuration.getResultMap(Configuration.java:718) ~[mybatis-3.5.5.jar:3.5.5]at org.apache.ibatis.builder.MapperBuilderAssistant.getStatementResultMaps(MapperBuilderAssistant.java:394) ~[mybatis-3.5.5.jar:3.5.5]at org.apache.ibatis.builder.MapperBuilderAssistant.addMappedStatement(MapperBuilderAssistant.java:285) ~[mybatis-3.5.5.jar:3.5.5]

定位到問題發生位置后，百度解決：

百度后說是

?如上圖，確實用錯了

修改如下圖，也是不對的。

我要查的是多條實體。最后改為下圖這樣就好了。

?前面是我想錯了，這里?resultMap 是返回結果的每一個實體的的類型，而不是返回結果的類型

4、Application run failed 啟動失敗

錯誤狀況：

09:50:14.499 [main] DEBUG org.springframework.boot.context.logging.ClasspathLoggingApplicationListener - Application failed to start with classpath: [file:/D:/jdk1.8.0_101/jre/lib/resources.jar, file:/D:/jdk1.8.0_101/jre/lib/rt.jar, file:/D:/jdk1.8.0_101/jre/lib/jsse.jar, file:/D:/jdk1.8.0_101/jre/lib/jce.jar, file:/D:/jdk1.8.0_101/jre/lib/charsets.jar, file:/D:/jdk1.8.0_101/jre/lib/jfr.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/access-bridge-64.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/cldrdata.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/dnsns.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/jaccess.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/jfxrt.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/localedata.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/nashorn.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunec.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunjce_provider.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunmscapi.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/sunpkcs11.jar, file:/D:/jdk1.8.0_101/jre/lib/ext/zipfs.jar, file:/D:/Work/springboot_demo/target/classes/, file:/D:/tomcat/apache-tomcat-9.0.60/lib/annotations-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-ant.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-ha.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-ssi.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-storeconfig.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina-tribes.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/catalina.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/ecj-4.20.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/el-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jasper-el.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jasper.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jaspic-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/jsp-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/servlet-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-api.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-coyote.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-dbcp.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-cs.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-de.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-es.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-fr.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-ja.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-ko.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-pt-BR.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-ru.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-i18n-zh-CN.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-jdbc.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-jni.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-util-scan.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-util.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/tomcat-websocket.jar, file:/D:/tomcat/apache-tomcat-9.0.60/lib/websocket-api.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-web/2.3.1.RELEASE/spring-boot-starter-web-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter/2.3.1.RELEASE/spring-boot-starter-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot/2.3.1.RELEASE/spring-boot-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.3.1.RELEASE/spring-boot-autoconfigure-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-logging/2.3.1.RELEASE/spring-boot-starter-logging-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar, file:/C:/Users/397004497/.m2/repository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar, file:/C:/Users/397004497/.m2/repository/org/apache/logging/log4j/log4j-to-slf4j/2.13.3/log4j-to-slf4j-2.13.3.jar, file:/C:/Users/397004497/.m2/repository/org/apache/logging/log4j/log4j-api/2.13.3/log4j-api-2.13.3.jar, file:/C:/Users/397004497/.m2/repository/org/slf4j/jul-to-slf4j/1.7.30/jul-to-slf4j-1.7.30.jar, file:/C:/Users/397004497/.m2/repository/jakarta/annotation/jakarta.annotation-api/1.3.5/jakarta.annotation-api-1.3.5.jar, file:/C:/Users/397004497/.m2/repository/org/yaml/snakeyaml/1.26/snakeyaml-1.26.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-json/2.3.1.RELEASE/spring-boot-starter-json-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.11.0/jackson-databind-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/core/jackson-annotations/2.11.0/jackson-annotations-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.11.0/jackson-core-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.11.0/jackson-datatype-jdk8-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.11.0/jackson-datatype-jsr310-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/jackson/module/jackson-module-parameter-names/2.11.0/jackson-module-parameter-names-2.11.0.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-tomcat/2.3.1.RELEASE/spring-boot-starter-tomcat-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/apache/tomcat/embed/tomcat-embed-core/9.0.36/tomcat-embed-core-9.0.36.jar, file:/C:/Users/397004497/.m2/repository/org/glassfish/jakarta.el/3.0.3/jakarta.el-3.0.3.jar, file:/C:/Users/397004497/.m2/repository/org/apache/tomcat/embed/tomcat-embed-websocket/9.0.36/tomcat-embed-websocket-9.0.36.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-web/5.2.7.RELEASE/spring-web-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-beans/5.2.7.RELEASE/spring-beans-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-webmvc/5.2.7.RELEASE/spring-webmvc-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-context/5.2.7.RELEASE/spring-context-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-expression/5.2.7.RELEASE/spring-expression-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-data-jpa/2.3.1.RELEASE/spring-boot-starter-data-jpa-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-jdbc/2.3.1.RELEASE/spring-boot-starter-jdbc-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/com/zaxxer/HikariCP/3.4.5/HikariCP-3.4.5.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-jdbc/5.2.7.RELEASE/spring-jdbc-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/jakarta/transaction/jakarta.transaction-api/1.3.3/jakarta.transaction-api-1.3.3.jar, file:/C:/Users/397004497/.m2/repository/jakarta/persistence/jakarta.persistence-api/2.2.3/jakarta.persistence-api-2.2.3.jar, file:/C:/Users/397004497/.m2/repository/org/hibernate/hibernate-core/5.4.17.Final/hibernate-core-5.4.17.Final.jar, file:/C:/Users/397004497/.m2/repository/org/jboss/logging/jboss-logging/3.4.1.Final/jboss-logging-3.4.1.Final.jar, file:/C:/Users/397004497/.m2/repository/org/javassist/javassist/3.24.0-GA/javassist-3.24.0-GA.jar, file:/C:/Users/397004497/.m2/repository/net/bytebuddy/byte-buddy/1.10.11/byte-buddy-1.10.11.jar, file:/C:/Users/397004497/.m2/repository/antlr/antlr/2.7.7/antlr-2.7.7.jar, file:/C:/Users/397004497/.m2/repository/org/jboss/jandex/2.1.3.Final/jandex-2.1.3.Final.jar, file:/C:/Users/397004497/.m2/repository/com/fasterxml/classmate/1.5.1/classmate-1.5.1.jar, file:/C:/Users/397004497/.m2/repository/org/dom4j/dom4j/2.1.3/dom4j-2.1.3.jar, file:/C:/Users/397004497/.m2/repository/org/hibernate/common/hibernate-commons-annotations/5.1.0.Final/hibernate-commons-annotations-5.1.0.Final.jar, file:/C:/Users/397004497/.m2/repository/org/glassfish/jaxb/jaxb-runtime/2.3.3/jaxb-runtime-2.3.3.jar, file:/C:/Users/397004497/.m2/repository/org/glassfish/jaxb/txw2/2.3.3/txw2-2.3.3.jar, file:/C:/Users/397004497/.m2/repository/com/sun/istack/istack-commons-runtime/3.0.11/istack-commons-runtime-3.0.11.jar, file:/C:/Users/397004497/.m2/repository/com/sun/activation/jakarta.activation/1.2.2/jakarta.activation-1.2.2.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/data/spring-data-jpa/2.3.1.RELEASE/spring-data-jpa-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/data/spring-data-commons/2.3.1.RELEASE/spring-data-commons-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-orm/5.2.7.RELEASE/spring-orm-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-tx/5.2.7.RELEASE/spring-tx-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-aspects/5.2.7.RELEASE/spring-aspects-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/mysql/mysql-connector-java/8.0.20/mysql-connector-java-8.0.20.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/spring/boot/mybatis-spring-boot-starter/2.1.3/mybatis-spring-boot-starter-2.1.3.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/spring/boot/mybatis-spring-boot-autoconfigure/2.1.3/mybatis-spring-boot-autoconfigure-2.1.3.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/mybatis/3.5.5/mybatis-3.5.5.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/mybatis-spring/2.0.5/mybatis-spring-2.0.5.jar, file:/C:/Users/397004497/.m2/repository/jakarta/xml/bind/jakarta.xml.bind-api/2.3.3/jakarta.xml.bind-api-2.3.3.jar, file:/C:/Users/397004497/.m2/repository/jakarta/activation/jakarta.activation-api/1.2.2/jakarta.activation-api-1.2.2.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-core/5.2.7.RELEASE/spring-core-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-jcl/5.2.7.RELEASE/spring-jcl-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/com/alibaba/druid-spring-boot-starter/1.2.6/druid-spring-boot-starter-1.2.6.jar, file:/C:/Users/397004497/.m2/repository/com/alibaba/druid/1.2.6/druid-1.2.6.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/boot/spring-boot-starter-aop/2.3.1.RELEASE/spring-boot-starter-aop-2.3.1.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/springframework/spring-aop/5.2.7.RELEASE/spring-aop-5.2.7.RELEASE.jar, file:/C:/Users/397004497/.m2/repository/org/aspectj/aspectjweaver/1.9.5/aspectjweaver-1.9.5.jar, file:/C:/Users/397004497/.m2/repository/org/mybatis/generator/mybatis-generator-core/1.3.5/mybatis-generator-core-1.3.5.jar] 09:50:14.848 [main] ERROR org.springframework.boot.SpringApplication - Application run failed java.lang.IllegalStateException: Failed to load property source from 'file:/D:/Work/springboot_demo/target/classes/application.yml' (classpath:/application.yml)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:554)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.loadForFileExtension(ConfigFileApplicationListener.java:499)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:469)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$null$7(ConfigFileApplicationListener.java:448)at java.lang.Iterable.forEach(Iterable.java:75)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$load$8(ConfigFileApplicationListener.java:448)at java.lang.Iterable.forEach(Iterable.java:75)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:445)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.lambda$load$0(ConfigFileApplicationListener.java:348)at org.springframework.boot.context.config.FilteredPropertySource.apply(FilteredPropertySource.java:54)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:336)at org.springframework.boot.context.config.ConfigFileApplicationListener.addPropertySources(ConfigFileApplicationListener.java:226)at org.springframework.boot.context.config.ConfigFileApplicationListener.postProcessEnvironment(ConfigFileApplicationListener.java:210)at org.springframework.boot.context.config.ConfigFileApplicationListener.onApplicationEnvironmentPreparedEvent(ConfigFileApplicationListener.java:200)at org.springframework.boot.context.config.ConfigFileApplicationListener.onApplicationEvent(ConfigFileApplicationListener.java:188)at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:80)at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:345)at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)at com.lx.springboot_demo.Application.main(Application.java:19) Caused by: org.yaml.snakeyaml.scanner.ScannerException: while scanning for the next token found character '\t(TAB)' that cannot start any token. (Do not use \t(TAB) for indentation)in 'reader', line 39, column 1:mapper-locations: class:mappers ... ^at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:419)at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:227)at org.yaml.snakeyaml.parser.ParserImpl$ParseBlockMappingValue.produce(ParserImpl.java:586)at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:158)at org.yaml.snakeyaml.parser.ParserImpl.checkEvent(ParserImpl.java:148)at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:136)at org.yaml.snakeyaml.composer.Composer.composeValueNode(Composer.java:257)at org.yaml.snakeyaml.composer.Composer.composeMappingChildren(Composer.java:248)at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:236)at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:162)at org.yaml.snakeyaml.composer.Composer.getNode(Composer.java:95)at org.yaml.snakeyaml.constructor.BaseConstructor.getData(BaseConstructor.java:134)at org.yaml.snakeyaml.Yaml$1.next(Yaml.java:494)at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:200)at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:164)at org.springframework.boot.env.OriginTrackedYamlLoader.load(OriginTrackedYamlLoader.java:76)at org.springframework.boot.env.YamlPropertySourceLoader.load(YamlPropertySourceLoader.java:50)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.loadDocuments(ConfigFileApplicationListener.java:608)at org.springframework.boot.context.config.ConfigFileApplicationListener$Loader.load(ConfigFileApplicationListener.java:524)... 25 common frames omitted

java.lang.IllegalStateException: Failed to load property source from 'file:/D:/Work/springboot_demo/target/classes/application.yml' (classpath:/application.yml)

如上圖，它總是提示我，這塊有問題，可是我檢查，yml配置文件，看起來沒寫錯

?小小分析：

注意看這里

這個算是小箭頭吧，它標注的位置，在我代碼前面的空白

我沒明白，不過我各種實驗過，反正只要把 mybatis：這些東西全刪除，居然能正常啟動，并且正常調用返回。那我確定就是mybatis這塊寫錯了。

解決方案：

最終，實驗到我把前面空白去掉，他就不報這一行錯誤。

然后和上面復制粘貼過來的進行對比，發現，這幾行報錯的前面我按得是 “Tab” 按鍵，而正確的代碼里，前面的空白用的是多個? ?空格? 鍵

?修改后，如下：

mybatis:mapper-locations: class:mappers/*.xmltype-aliases-package: com.lx.springboot_demo.modelconfiguration:map-underscore-to-camel-case: true

把前面縮進的位置都用? 空格? 鍵來縮進

啟動，問題解決。

5、啟動已經沒問題，但是控制臺有一個警告

警告詳情：

啟動時，控制臺如下：

. ____ _ __ _ _/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/ ___)| |_)| | | | | || (_| | ) ) ) )' |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot :: (v2.3.1.RELEASE)2022-04-06 10:04:00.230 INFO 28028 --- [ main] com.lx.springboot_demo.Application : Starting Application on LAPTOP-710QH23H with PID 28028 (D:\Work\springboot_demo\target\classes started by 397004497 in D:\Work\springboot_demo) 2022-04-06 10:04:00.233 INFO 28028 --- [ main] com.lx.springboot_demo.Application : No active profile set, falling back to default profiles: default 2022-04-06 10:04:01.983 INFO 28028 --- [ main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFERRED mode. 2022-04-06 10:04:02.015 INFO 28028 --- [ main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 20ms. Found 0 JPA repository interfaces. 2022-04-06 10:04:04.386 INFO 28028 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http) 2022-04-06 10:04:04.453 INFO 28028 --- [ main] o.apache.catalina.core.StandardService : 正在啟動服務[Tomcat] 2022-04-06 10:04:04.453 INFO 28028 --- [ main] org.apache.catalina.core.StandardEngine : 正在啟動 Servlet 引擎：[Apache Tomcat/9.0.60] 2022-04-06 10:04:04.454 WARN 28028 --- [ main] o.a.catalina.core.AprLifecycleListener : This listener must only be nested within Server elements, but is in [TomcatEmbeddedContext]. 2022-04-06 10:04:04.455 INFO 28028 --- [ main] o.a.catalina.core.AprLifecycleListener : 使用APR版本[1.7.0]加載了基于APR的Apache Tomcat本機庫[1.2.31]。 2022-04-06 10:04:04.455 INFO 28028 --- [ main] o.a.catalina.core.AprLifecycleListener : APR功能：IPv6[true]、sendfile[true]、accept filters[false]、random[true]、UDS [true]。 2022-04-06 10:04:04.455 INFO 28028 --- [ main] o.a.catalina.core.AprLifecycleListener : APR/OpenSSL配置：useAprConnector[false]，useOpenSSL[true] 2022-04-06 10:04:04.635 INFO 28028 --- [ main] o.a.catalina.core.AprLifecycleListener : OpenSSL成功初始化 [OpenSSL 1.1.1l 24 Aug 2021] 2022-04-06 10:04:05.643 INFO 28028 --- [ main] org.apache.jasper.servlet.TldScanner : 至少有一個JAR被掃描用于TLD但尚未包含TLD。為此記錄器啟用調試日志記錄，以獲取已掃描但未在其中找到TLD的完整JAR列表。在掃描期間跳過不需要的JAR可以縮短啟動時間和JSP編譯時間。 2022-04-06 10:04:05.647 INFO 28028 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2022-04-06 10:04:05.648 INFO 28028 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 5329 ms 2022-04-06 10:04:05.926 INFO 28028 --- [ main] c.a.d.s.b.a.DruidDataSourceAutoConfigure : Init DruidDataSource Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary. 2022-04-06 10:04:10.829 INFO 28028 --- [ main] com.alibaba.druid.pool.DruidDataSource : {dataSource-1} inited 2022-04-06 10:04:11.091 INFO 28028 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor' 2022-04-06 10:04:11.285 INFO 28028 --- [ task-1] o.hibernate.jpa.internal.util.LogHelper : HHH000204: Processing PersistenceUnitInfo [name: default] 2022-04-06 10:04:11.488 INFO 28028 --- [ task-1] org.hibernate.Version : HHH000412: Hibernate ORM core version 5.4.17.Final 2022-04-06 10:04:12.192 WARN 28028 --- [ main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning 2022-04-06 10:04:12.277 INFO 28028 --- [ task-1] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {5.1.0.Final} 2022-04-06 10:04:12.948 INFO 28028 --- [ task-1] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.MySQL57Dialect 2022-04-06 10:04:13.545 INFO 28028 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path '' 2022-04-06 10:04:13.546 INFO 28028 --- [ main] DeferredRepositoryInitializationListener : Triggering deferred initialization of Spring Data repositories… 2022-04-06 10:04:13.547 INFO 28028 --- [ main] DeferredRepositoryInitializationListener : Spring Data repositories initialized! 2022-04-06 10:04:13.567 INFO 28028 --- [ main] com.lx.springboot_demo.Application : Started Application in 14.39 seconds (JVM running for 14.968) 2022-04-06 10:04:13.824 INFO 28028 --- [ task-1] o.h.e.t.j.p.i.JtaPlatformInitiator : HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform] 2022-04-06 10:04:13.839 INFO 28028 --- [ task-1] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'

出現了

一行紅字，百度翻譯了下

正在加載class`com。mysql。jdbc。司機。這是不贊成的。新的驅動程序類是'com。mysql。希杰。jdbc。司機。驅動程序通過SPI自動注冊，通常不需要手動加載驅動程序類。

意思是：不贊成加載 “com.mysql.jdbc.Driver” 驅動。新的驅動程序類 “com.mysql.cj.jdbc.Driver”。自動注冊，不需要手動加載

問題所在：

配置文件加載驅動應該改了

解決問題：

修改驅動類名

總結

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javascript

Eclipse 工具上Springboot项目的简单 增删改查 的搭建

一、為嘛子要學習Springboot

二、簡單的說下springboot

三、咱們對比看看唄

四、開始操作，建項目

1、建一個maven項目

2、pom.xml 依賴 以及 配置文件

①簡單的依賴如下，我就不細說了

②配置文件，application.yml

3、創建相應的包結構

4、使用?Mybatis Generator 自動生成實體類、mapper和mapper.xml文件

5、填寫各個包的內容

①mapper? 增加一個方法

②mapper.xml 的寫法

③service 層接口的編寫

④service 的 Impl 實現類

⑤Controller 層

五、運行

六、遇到的問題以及解決方案

1、剛建好項目，啥都沒干呢就看到 index.jsp 紅叉，如下：

錯誤狀況：

?解決方案：

2、項目基本寫完，沒看到紅叉之類的錯誤提示，但是一運行，報錯

錯誤狀況：

小小分析：

解決方案：

3、再次運行，又報錯了，

錯誤狀況：

查找問題：

定位到問題發生位置后，百度解決：

4、Application run failed 啟動失敗

?小小分析：

解決方案：

5、啟動已經沒問題，但是控制臺有一個警告

警告詳情：

問題所在：

解決問題：

總結

Eclipse 工具上Springboot项目的简单增删改查的搭建

2、pom.xml 依賴以及配置文件