springboot 和 mybatis整合:参数查询和动态sql
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springboot 和 mybatis整合:参数查询和动态sql
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springboot 和 mybatis整合:
mapper定義的是數據庫的操作方法:
@Mapper public interface UserMapper {}單參數的處理:
@Select("select * from t_user")@Results({@Result(property = "userId", column = "USER_ID"),@Result(property = "username", column = "USERNAME"),@Result(property = "password", column = "PASSWORD"),@Result(property = "mobileNum", column = "PHONE_NUM")})List<User> list();多參數的處理:
/*** 延伸:無論什么方式,如果涉及多個參數,則必須加上@Param注解,否則無法使用EL表達式獲取參數。*/@Select("select * from t_user where username like #{username} and password like #{password}")@Results({@Result(property = "userId", column = "USER_ID"),@Result(property = "username", column = "USERNAME"),@Result(property = "password", column = "PASSWORD"),@Result(property = "mobileNum", column = "PHONE_NUM")})User get(@Param("username") String username, @Param("password") String password);CRUD的高級注解:
@SelectProvider
@InsertProvider
@UpdateProvider
@DeleteProvider
先在mapper下定義Provider,所謂的Provider就是自定義的sql語句,規則可以自定義
public class UserSqlProvider {/*** 方式1:在工具類的方法里,可以自己手工編寫SQL。*/public String listByUsername(String username) {return "select * from t_user where username =#{username}";} }然后定義使用這個sql語句的方法,就在對應的mapper里面操作:
/*** 方式2:使用注解指定某個工具類的方法來動態編寫SQL.*/@SelectProvider(type = UserSqlProvider.class, method = "listByUsername")@Results({@Result(property = "userId", column = "USER_ID"),@Result(property = "username", column = "USERNAME"),@Result(property = "password", column = "PASSWORD"),@Result(property = "mobileNum", column = "PHONE_NUM")})List<User> listByUsername(String username);controller里面使用:
@GetMapping("list/{username}")public List<User> listByUsername(@PathVariable("username") String username) {return userMapper.listByUsername(username);}another samples:
UserSqlProvider.java /*** 方式2:也可以根據官方提供的API來編寫動態SQL。*/public String getBadUser(@Param("username") String username, @Param("password") String password) {return new SQL() {{SELECT("*");FROM("t_user");if (username != null && password != null) {WHERE("username like #{username} and password like #{password}");} else {WHERE("1=2");}}}.toString();}UserMapper.java@SelectProvider(type = UserSqlProvider.class, method = "getBadUser")@Results({@Result(property = "userId", column = "USER_ID"),@Result(property = "username", column = "USERNAME"),@Result(property = "password", column = "PASSWORD"),@Result(property = "mobileNum", column = "PHONE_NUM")})User getBadUser(@Param("username") String username, @Param("password") String password);UserController.java@GetMapping("get/bad/{username}/{password}")public User getBadUser(@PathVariable("username") String username, @PathVariable("password") String password) {return userMapper.getBadUser(username, password);}總結
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