文件结构目录：
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pom.xml：
添加mybatis、mysql、web依赖，这里的mybatis会关联jdbc的依赖，所以可以不添加jdbc的依赖。web只是为了方便测试，并非必须。
<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.bingo</groupId>
<artifactId>springbootmybatis-anno</artifactId>
<version>1.0-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.6.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--mybatis -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
</dependencies>
</project>
在resources资源文件夹中添加application.yml：
spring:
datasource:
url: jdbc:mysql://localhost:3306/springbootmybatis?characterEncoding=UTF-8&useSSL=false
username: root
password: 123456
driver-class-name: com.mysql.jdbc.Driver
mybatis:
type-aliases-package: com.demo.pojo
添加实体类：
这里如果getter和setter方法的名称与数据库中存放的一致，则能够自动和数据库映射匹配，这边设置成一致。这边不会有驼峰命名到下划线命名的这种转换关系。一旦有一个不匹配，直接该不匹配的返回null，其余的仍然能正常得到数据。
package com.demo.pojo;
// 会根据getter和setter方法名称和数据库成员名字进行匹配
// 如果一致，那么无需额外配置
public class User {
private Integer id;
private String username;
private String password;
private String realname;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getRealname() {
return realname;
}
public void setRealname(String realname) {
this.realname = realname;
}
}
添加mapper接口：
利用注解添加方法。
package com.demo.mapper;
import com.demo.pojo.User;
import org.apache.ibatis.annotations.*;
import java.util.List;
@Mapper
public interface UserMapper{
@Select("select * from user where id = #{id}")
User selectByPrimaryKey(@Param("id") int id);
@Select("select * from user")
List<User> selectAll();
@Delete("delete from user where id = #{id}")
int deleteByPrimaryKey(@Param("id") int id);
@Update("update user set username = #{username}, password = #{password}, realname = #{realname} where id = #{id}")
int update(@Param("id") int id, @Param("username") String username, @Param("password") String password, @Param("realname") String realname);
@Insert("insert into user(username, password) values(#{username}, #{password})")
int insert(@Param("username") String username, @Param("password") String password);
}
添加引导类：
package com.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class ApplicationBoot {
public static void main(String[] args) {
SpringApplication.run(ApplicationBoot.class, args);
}
}
定义service接口：
定义增删改查的抽象方法。
package com.demo.service;
import com.demo.pojo.User;
import java.util.List;
public interface UserService {
/**
* 根据id查询某一个具体的User
*
* @param id
* @return
*/
User queryById(int id);
/**
* 查询全体User信息
*
* @return
*/
List<User> queryAll();
/**
* 根据id删除掉某个User
*
* @param id
* @return
*/
int deleteById(int id);
/**
* 更新一个用户信息
*
* @param id
* @param username
* @param password
* @param realname
* @return
*/
int updateUser(int id, String username, String password, String realname);
/**
* 添加一个用户
*
* @param username
* @param password
* @return
*/
int insertUser(String username, String password);
}
定义service的实现类：
调用Mapper类里面提供的方法，来执行SQL语句。
package com.demo.service.impl;
import com.demo.mapper.UserMapper;
import com.demo.pojo.User;
import com.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
@Autowired
private UserMapper userMapper;
@Override
public User queryById(int id) {
return this.userMapper.selectByPrimaryKey(id);
}
@Override
public List<User> queryAll() {
return this.userMapper.selectAll();
}
@Override
@Transactional
public int deleteById(int id) {
return this.userMapper.deleteByPrimaryKey(id);
}
@Override
@Transactional
public int updateUser(int id, String username, String password, String realname) {
return this.userMapper.update(id, username, password, realname);
}
@Override
@Transactional
public int insertUser(String username, String password) {
return this.userMapper.insert(username, password);
}
}
写controller层进行测试：
package com.demo.controller;
import com.demo.pojo.User;
import com.demo.service.impl.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
// 用于测试
@RestController
@RequestMapping("user")
public class UserController {
@Autowired
private UserServiceImpl userServiceImpl;
// select
@RequestMapping(value = "/all", method = RequestMethod.GET)
public List<User> getAllUsers() {
return userServiceImpl.queryAll();
}
// select
@RequestMapping(value = "/{id}", method = RequestMethod.GET)
public User getUserById(@PathVariable("id") int id) {
return userServiceImpl.queryById(id);
}
// update
@RequestMapping(value = "/{id}", method = RequestMethod.PUT)
public String updateAccount(@PathVariable("id") int id,
@RequestParam(value = "username", required = true) String username,
@RequestParam(value = "password", required = true) String password,
@RequestParam(value = "realname", required = true) String realname) {
int t = userServiceImpl.updateUser(id, username, password, realname);
if (t == 1) {
return "success";
} else {
return "fail";
}
}
// delete
@RequestMapping(value = "/{id}", method = RequestMethod.DELETE)
public String delete(@PathVariable(value = "id") int id) {
int t = userServiceImpl.deleteById(id);
if (t == 1) {
return "success";
} else {
return "fail";
}
}
// post
@RequestMapping(value = "", method = RequestMethod.POST)
public String postAccount(@RequestParam(value = "username") String username,
@RequestParam(value = "password") String password) {
int t = userServiceImpl.insertUser(username, password);
if (t == 1) {
return "success";
} else {
return "fail";
}
}
@GetMapping("hello")
public String test() {
return "hello mybatis";
}
}
补充说明：
如果实体类名称和数据库名称不匹配(准确地说是getter和setter方法名和数据库不匹配)，可以通过以下方法来解决（这里我把username改成了name）：
得到的结果：
修改方法：
在mapper接口中添加@Results和@Result
package com.demo.mapper;
import com.demo.pojo.User;
import org.apache.ibatis.annotations.*;
import java.util.List;
@Mapper
public interface UserMapper {
@Results({
@Result(property = "id", column = "id"),
@Result(property = "name", column = "username"),
@Result(property = "password", column = "password"),
@Result(property = "realname", column = "realname")
})
@Select("select * from user where id = #{id}")
User selectByPrimaryKey(@Param("id") int id);
@Select("select * from user")
List<User> selectAll();
@Delete("delete from user where id = #{id}")
int deleteByPrimaryKey(@Param("id") int id);
@Update("update user set username = #{username}, password = #{password}, realname = #{realname} where id = #{id}")
int update(@Param("id") int id, @Param("username") String username, @Param("password") String password, @Param("realname") String realname);
@Insert("insert into user(username, password) values(#{username}, #{password})")
int insert(@Param("username") String username, @Param("password") String password);
}
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