一、配置MySQL数据库和MyBatis-Plus依赖

    
        
        
            mysql
            mysql-connector-java
            8.0.28
        
        
        
            com.baomidou
            mybatis-plus-boot-starter
            3.4.0
        
        
        
            org.projectlombok
            lombok
            provided
        
    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
        
        
            
                src/main/java
                
                    **/*.xml
                
                true
            
            
                src/main/resources
                
                    **/*.*
                
            
        
    

二、配置yml文件中MySQL的连接和Mybatis-Plus配置

spring:
  #  mysql配置信息
  datasource:
  	#                 数据库地址  端口  数据库名
    url: jdbc:mysql://127.0.0.1:3306/springboot_demo?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=GMT%2B8
    username: root	# 账号
    password: root	# 密码
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis-plus:
  mapper-locations: mapper/*.xml #这个配置是用来连接mapper接口和mapper配置类的
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #运行日志
    map-underscore-to-camel-case: true #驼峰转换
  type-aliases-package: com.example.springbootdemo.model #实体类扫描包

三、创建一个测试表并添加数据

四、测试使用MyBatis-Plus 查询数据

1、创建实体类

package com.example.springbootdemo.model;
import com.baomidou.mybatisplus.annotation.*;
import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.Data;
import java.util.Date;
/**
 * @ClassName: User
 * @Description:
 * @Author: WangBin
 * @Date: 2023/6/17 20:48
 */
@Data
@TableName("user")
public class User {
    /** id */
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;
    /** 名字 */
    private String name;
    /** 账号 */
    private String account;
    /** 密码 */
    private String password;
    /** 创建者 */
    private String createBy;
    /** 创建时间 */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss") // 规定时间数据格式
    private Date createTime;
    /** 更新者 */
    private String updateBy;
    /** 更新时间 */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss") // 规定时间数据格式
    private Date updateTime;
    /** 备注 */
    private String remark;
}

2、创建Controller

package com.example.springbootdemo.controller;
import com.example.springbootdemo.model.User;
import com.example.springbootdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
/**
 * @ClassName: UserController
 * @Description:
 * @Author: WangBin
 * @Date: 2023/6/17 21:07
 */
@RestController
public class UserController {
    @Autowired
    private UserService userService;
    /**
     * 根据ID查询用户(使用MyBatis-Plus方法查询)
     * @param userId
     * @return
     */
    @RequestMapping(value = "/queryUserById/{userId}", method = RequestMethod.GET)
    public User queryUserById(@PathVariable("userId") Integer userId){
        User user = userService.getById(userId);
        return user;
    }
    /**
     * 条件查询(使用MyBatis-Plus方法查询)
     * @param user
     * @return
     */
    @RequestMapping(value = "/getList", method = RequestMethod.POST)
    public List getList(@RequestBody User user){
        List list = userService.getList(user);
        return list;
    }
    /**
     * 根据姓名查询用户
     * @param name
     * @return
     */
    @RequestMapping(value = "/getUserByName",method = RequestMethod.GET)
    public List getUserByName(@RequestParam("name") String name){
        List users = userService.getUserByName(name);
        return users;
    }
    /**
     * 根据账号查询用户
     * @param account
     * @return
     */
    @RequestMapping(value = "/getUserByAccount",method = RequestMethod.GET)
    public User getUserByAccount(@RequestParam("account") String account){
        User user = userService.getUserByAccount(account);
        return user;
    }
}

3、创建service接口

package com.example.springbootdemo.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.example.springbootdemo.model.User;
import java.util.List;
/**
 * @ClassName: UserService
 * @Description:
 * @Author: WangBin
 * @Date: 2023/6/17 21:09
 */
public interface UserService extends IService {
    /**
     * 条件查询
     * @param user
     * @return
     */
    List getList(User user);
    /**
     * 根据姓名查询用户
     * @param name
     * @return
     */
    List getUserByName(String name);
    /**
     * 根据账号查询用户
     * @param account
     * @return
     */
    User getUserByAccount(String account);
}

4、创建Service实现类

package com.example.springbootdemo.service.impl;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.springbootdemo.mapper.UserMapper;
import com.example.springbootdemo.model.User;
import com.example.springbootdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
/**
 * @ClassName: UserServiceImpl
 * @Description:
 * @Author: WangBin
 * @Date: 2023/6/17 21:10
 */
@Service
public class UserServiceImpl extends ServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    /**
     * 条件查询
     * @param user
     * @return
     */
    @Override
    public List getList(User user) {
        QueryWrapper wrapper = new QueryWrapper<>();
        if (user.getId() != null && user.getId() > 0){
            wrapper.eq("id",user.getId());
        }
        if (user.getName() != null && user.getName() != ""){
            wrapper.like("name",user.getName());
        }
        // .....
        List list = userMapper.selectList(wrapper);
        return list;
    }
    /**
     * 根据姓名查询用户
     * @param name
     * @return
     */
    @Override
    public List getUserByName(String name) {
        List list = userMapper.getUserByName(name);
        return list;
    }
    @Override
    public User getUserByAccount(String account) {
        User user = userMapper.getUserByAccount(account);
        return user;
    }
}

5、创建Mapper

package com.example.springbootdemo.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.springbootdemo.model.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import java.util.List;
/**
 * @ClassName: UserMapper
 * @Description:
 * @Author: WangBin
 * @Date: 2023/6/17 20:27
 */
@Mapper
public interface UserMapper extends BaseMapper {
    @Select("select * from `user` where name=#{name}")
    List getUserByName(@Param("name") String name);
    User getUserByAccount(@Param("account") String account);
}

6、创建Mapper配置类

    
        select * from `user` where account=#{account}
    

五、接口测试

1、URL携带参数测试(通过\绑定)

2、POST请求体测试

3、URL携带参数测试(通过?绑定)