目标:配置通用Mapper组件到Spring Boot项目中并使用 Mapper<T>接口
分析:通用Mapper:可以实现自动拼接sql语句,所有的mapper都不用编写任何方法也就是不用编写sql语句,可以提高效率
1.添加启动器依赖
2.改造UserMapper继承Mapper<User>
3.修改启动器引导类Application中的Mapper扫描注解
4.修改User实体类添加jpa注解
5.改造UserService实现业务功能
注意:在启动引导类上面的mapper扫描注解一定要修改为通用mapper的扫描注解(不然mapper找不到)
==========
1.添加启动器依赖
<!--通用mapper-->
<dependency>
<groupId>tk.mybatis</groupId>
<artifactId>mapper-spring-boot-starter</artifactId>
<version>2.1.5</version>
</dependency>
2.改造UserMapper继承Mapper<User>
package com.cc8w.home.mapper;
import com.cc8w.com.cc8w.entity.User;
import org.apache.ibatis.session.RowBounds;
import tk.mybatis.mapper.common.Mapper;
import java.util.List;
public interface UserMapper extends Mapper<User> {
}
3.修改启动器引导类Application中的Mapper扫描注解
package com.cc8w;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import tk.mybatis.spring.annotation.MapperScan;
/**
* spring boot 工程都有一个启动引导类,
* 并且添加 @SpringBootApplication 组合注解
*/
@SpringBootApplication
//@MapperScan("com.cc8w.home.mapper") //扫描mapper接口
@MapperScan("com.cc8w.home.mapper")//使用通用mapper
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class,args);
}
}
4.修改User实体类添加jpa注解
package com.cc8w.com.cc8w.entity;
import lombok.Data;
import tk.mybatis.mapper.annotation.KeySql;
import javax.persistence.Column;
import javax.persistence.Id;
import javax.persistence.Table;
@Data
@Table(name="t_users")
public class User {
@Id
@KeySql(useGeneratedKeys = true) //id回填
private int id;
@Column(name="user_name")//符合驼峰命名可以不用
private String userName;
private String passWord;
}
5.改造UserService实现业务功能
package com.cc8w.home.service;
import com.cc8w.com.cc8w.entity.User;
import com.cc8w.home.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
@Service
public class UserService {
@Autowired
private UserMapper userMapper;
//根据id查询
public User queryById(int id){
return userMapper.selectByPrimaryKey(id);
}
//保存用户
@Transactional
public void saveUser(User user){
userMapper.insertSelective(user);
System.out.println("保存..");
}
}
试一下查询用户
package com.cc8w.home.controller;
import com.cc8w.com.cc8w.entity.User;
import com.cc8w.home.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.sql.DataSource;
@RestController
@RequestMapping("home/test")
public class JdbcTest {
@Autowired
private DataSource dataSource;
@Autowired
private UserService userService;
@RequestMapping("jtest")
public String jTest(){
System.out.println(dataSource);
System.out.println("jTest22");
User user = userService.queryById(1);
System.out.println(user);
return "null";
}
}