mybatis快速入门
mybatis快速入门
mybatis plus简化了mybatis开发，极大的提高了开发效率。
代码编写
实体类：
package com.example.mybatisplusdemo.entity;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
@Data
@TableName("user")
public class User {
private int id;
private String name;
private int age;
private String email;
}
mapper接口：
package com.example.mybatisplusdemo.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.mybatisplusdemo.entity.User;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface UserMapper extends BaseMapper<User> {
}
service类：
package com.example.mybatisplusdemo.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.example.mybatisplusdemo.entity.User;
import java.util.Collection;
import java.util.Map;
import java.util.function.Function;
public interface UserService extends IService<User> {
}
package com.example.mybatisplusdemo.service.impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.mybatisplusdemo.entity.User;
import com.example.mybatisplusdemo.mapper.UserMapper;
import com.example.mybatisplusdemo.service.UserService;
import org.springframework.stereotype.Service;
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}
controller类：
package com.example.mybatisplusdemo.controller;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.mybatisplusdemo.entity.User;
import com.example.mybatisplusdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
@PostMapping("/add")
public String add(@RequestBody User user){
boolean save = userService.save(user);
return save ? "添加成功" : "添加失败";
}
@GetMapping("list")
public List<User> list(){
return userService.list();
}
// 根据用户id查询用户
@GetMapping("/{id}")
public User getUserById(@PathVariable long id){
User user = userService.getById(id);
return user;
}
// 根据id更新用户信息
@PostMapping("/update")
public boolean updateById(@RequestBody User user){
return userService.saveOrUpdate(user);
}
// 根据普通条件更新用户信息
// 或者创建一个VO对象用来接受前端传过来的信息
@PostMapping("condition")
public boolean updateByCondition(@RequestBody Map<String, Object> map){
LambdaUpdateWrapper<User> wrapper = new LambdaUpdateWrapper<>();
wrapper.eq(User::getEmail, map.get("emailWhere"));
wrapper.set(User::getAge, map.get("age"));
wrapper.set(User::getName, map.get("name"));
wrapper.set(User::getEmail, map.get("email"));
return userService.update(wrapper);
}
@DeleteMapping("/{id}")
public boolean deleteById(@PathVariable long id){
boolean flag = userService.removeById(id);
return flag;
}
// 分页查询用户
@GetMapping("/page")
public Page<User> getUserPage(@RequestParam(defaultValue = "1") int current, @RequestParam(defaultValue = "10") int size) {
// 创建查询条件，这里不设置条件表示查询所有记录
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
// 创建分页对象，current 表示当前页码，size 表示每页记录数
Page<User> page = new Page<>(current, size);
return userService.page(page, queryWrapper);
}
// 条件查询用户
@GetMapping("/query")
public List<User> queryUsers(@RequestParam String name, @RequestParam int age) {
QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.eq("name", name).eq("age", age);
return userService.list(wrapper);
}
}
启动类：
package com.example.mybatisplusdemo;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
//@MapperScan
public class MybatisplusdemoApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisplusdemoApplication.class, args);
}
}
数据库脚本：
-- mytest.`user` definition
CREATE TABLE `user` (
`id` int NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
`age` int DEFAULT NULL,
`email` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',13,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',14,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',15,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',16,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',17,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',18,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',19,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',20,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',21,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',22,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',23,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',24,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',25,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',26,'110100@qq.com');
INSERT INTO mytest.`user` (name,age,email) VALUES ('doudou',27,'110100@qq.com');
执行情况
添加用户：
查询所有用户：
通过id查询用户：
通过id删除用户：
根据条件查询用户：
分页查询：
添加配置类：
package com.example.mybatisplusdemo.configuration;
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MyBatisPlusConfig {
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
// 添加分页插件
interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
return interceptor;
}
}
{
"records": [
{
"id": 14,
"name": "doudou",
"age": 21,
"email": "110100@qq.com"
},
{
"id": 15,
"name": "doudou",
"age": 22,
"email": "110100@qq.com"
},
{
"id": 16,
"name": "doudou",
"age": 23,
"email": "110100@qq.com"
},
{
"id": 17,
"name": "doudou",
"age": 24,
"email": "110100@qq.com"
},
{
"id": 18,
"name": "doudou",
"age": 25,
"email": "110100@qq.com"
},
{
"id": 19,
"name": "doudou",
"age": 26,
"email": "110100@qq.com"
},
{
"id": 20,
"name": "doudou",
"age": 27,
"email": "110100@qq.com"
}
],
"total": 17,
"size": 10,
"current": 2,
"orders": [],
"optimizeCountSql": true,
"searchCount": true,
"countId": null,
"maxLimit": null,
"pages": 2
}
==> Preparing: SELECT id,name,age,email FROM user LIMIT ?,?
==> Parameters: 10(Long), 10(Long)
<== Columns: id, name, age, email
<== Row: 14, doudou, 21, 110100@qq.com
<== Row: 15, doudou, 22, 110100@qq.com
<== Row: 16, doudou, 23, 110100@qq.com
<== Row: 17, doudou, 24, 110100@qq.com
<== Row: 18, doudou, 25, 110100@qq.com
<== Row: 19, doudou, 26, 110100@qq.com
<== Row: 20, doudou, 27, 110100@qq.com
<== Total: 7
根据id更新用户信息：
根据普通条件更新用户信息：
实际使用过程中遇到的问题
如果在启动类上加上@MapperScan注解的话，会报错：org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.mybatisplusdemo.service.UserService.getBaseMapper
所以要将@MapperScan注解去掉。
如果测试过程中返回400的错误表示，请求方式不对，比如应该使用post请求，结果你使用的是get请求。
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