JDBC 框架概述

在使用普通的 JDBC 數據庫時，就會很麻煩的寫不必要的代碼來處理異常，打開和關閉數據庫連接等。但 Spring JDBC 框架負責所有的低層細節，從開始打開連接，準備和執行 SQL 語句，處理異常，處理事務，到最后關閉連接。

所以當從數據庫中獲取數據時，你所做的是定義連接參數，指定要執行的 SQL 語句，每次迭代完成所需的工作。

Spring JDBC 提供幾種方法和數據庫中相應的不同的類與接口。我將給出使用?JdbcTemplate?類框架的經典和最受歡迎的方法。這是管理所有數據庫通信和異常處理的中央框架類。

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JdbcTemplate 類

JdbcTemplate 類執行 SQL 查詢、更新語句和存儲過程調用，執行迭代結果集和提取返回參數值。它也捕獲 JDBC 異常并轉換它們到 org.springframework.dao 包中定義的通用類、更多的信息、異常層次結構。

JdbcTemplate?類的實例是線程安全配置的。所以你可以配置 JdbcTemplate 的單個實例，然后將這個共享的引用安全地注入到多個 DAOs 中。

使用 JdbcTemplate 類時常見的做法是在你的 Spring 配置文件中配置數據源，然后共享數據源 bean 依賴注入到 DAO 類中，并在數據源的設值函數中創建了 JdbcTemplate。

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演示示例如下:

(1)建立mysql數據庫，并導入該腳本，庫名可任意命名，這里命名為test,sql腳本為:

CREATE TABLE Student(ID INT NOT NULL AUTO_INCREMENT,NAME VARCHAR(20) NOT NULL,AGE INT NOT NULL,PRIMARY KEY (ID) );

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(2)創建實體

package com.tutorialspoint; public class Student {private Integer age;private String name;private Integer id;public void setAge(Integer age) {this.age = age;}public Integer getAge() {return age;}public void setName(String name) {this.name = name;}public String getName() {return name;}public void setId(Integer id) {this.id = id;}public Integer getId() {return id;} }

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(3)創建DAO

package com.tutorialspoint; import java.util.List; import javax.sql.DataSource; public interface StudentDAO {/** * This is the method to be used to initialize* database resources ie. connection.*/public void setDataSource(DataSource ds);/** * This is the method to be used to create* a record in the Student table.*/public void create(String name, Integer age);/** * This is the method to be used to list down* a record from the Student table corresponding* to a passed student id.*/public Student getStudent(Integer id);/** * This is the method to be used to list down* all the records from the Student table.*/public List<Student> listStudents();/** * This is the method to be used to delete* a record from the Student table corresponding* to a passed student id.*/public void delete(Integer id);/** * This is the method to be used to update* a record into the Student table.*/public void update(Integer id, Integer age); }

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(4)創建StudentMapper

package com.tutorialspoint; import java.sql.ResultSet; import java.sql.SQLException; import org.springframework.jdbc.core.RowMapper; public class StudentMapper implements RowMapper<Student> {public Student mapRow(ResultSet rs, int rowNum) throws SQLException {Student student = new Student();student.setId(rs.getInt("id"));student.setName(rs.getString("name"));student.setAge(rs.getInt("age"));return student;} }

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(5)創建StudentJDBCTemplate

package com.tutorialspoint; import java.util.List; import javax.sql.DataSource; import org.springframework.jdbc.core.JdbcTemplate; public class StudentJDBCTemplate implements StudentDAO {private DataSource dataSource;private JdbcTemplate jdbcTemplateObject; public void setDataSource(DataSource dataSource) {this.dataSource = dataSource;this.jdbcTemplateObject = new JdbcTemplate(dataSource);}public void create(String name, Integer age) {String SQL = "insert into Student (name, age) values (?, ?)"; jdbcTemplateObject.update( SQL, name, age);System.out.println("Created Record Name = " + name + " Age = " + age);return;}public Student getStudent(Integer id) {String SQL = "select * from Student where id = ?";Student student = jdbcTemplateObject.queryForObject(SQL, new Object[]{id}, new StudentMapper());return student;}public List<Student> listStudents() {String SQL = "select * from Student";List <Student> students = jdbcTemplateObject.query(SQL, new StudentMapper());return students;}public void delete(Integer id){String SQL = "delete from Student where id = ?";jdbcTemplateObject.update(SQL, id);System.out.println("Deleted Record with ID = " + id );return;}public void update(Integer id, Integer age){String SQL = "update Student set age = ? where id = ?";jdbcTemplateObject.update(SQL, age, id);System.out.println("Updated Record with ID = " + id );return;} }

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(6)編寫對應的Beans.xml

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.0.xsd "><!-- Initialization for data source --><bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"><property name="driverClassName" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="1234"/></bean><!-- Definition for studentJDBCTemplate bean --><bean id="studentJDBCTemplate" class="com.tutorialspoint.StudentJDBCTemplate"><property name="dataSource" ref="dataSource" /> </bean></beans>

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(7)編寫MainApp.java并運行

package com.tutorialspoint; import java.util.List;import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainApp {public static void main(String[] args) {ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate)context.getBean("studentJDBCTemplate"); System.out.println("------Records Creation--------" );studentJDBCTemplate.create("Zara", 11);studentJDBCTemplate.create("Nuha", 2);studentJDBCTemplate.create("Ayan", 15);System.out.println("------Listing Multiple Records--------" );List<Student> students = studentJDBCTemplate.listStudents();for (Student record : students) {System.out.print("ID : " + record.getId() );System.out.print(", Name : " + record.getName() );System.out.println(", Age : " + record.getAge());}System.out.println("----Updating Record with ID = 2 -----" );studentJDBCTemplate.update(2, 20);System.out.println("----Listing Record with ID = 2 -----" );Student student = studentJDBCTemplate.getStudent(2);System.out.print("ID : " + student.getId() );System.out.print(", Name : " + student.getName() );System.out.println(", Age : " + student.getAge()); } }

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運行結果如下:

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數據表數據由無變為有:

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轉載于:https://www.cnblogs.com/youcong/p/9460819.html

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