【开发篇】10分钟快速上手spring boot+mybatis增删改查

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首先来，温故而知新！！！

之前的预备知识：

• 10分钟快速上手git与github
• 10分钟快速上手springboot
• 10分钟快速springboot+react前后端分离

复习完之前，那么接接下来乘风破浪吧！！！

本次用IDEA带领你快速上手spring boot+mybatis进行用户的增删改查操作。

一、新建spring boot 项目

本次所用的依赖包含spring boot的核心web以及mysql,mybatis依赖包。

其依赖在pom.xml中如下所示:

<!--mybatis-->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.3</version>
</dependency>
<!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>

二、项目中配置mysql和mybatis

本次通过application.yml文件来配置信息，将application.properties文件删除，重新新建一个application.yml文件。其内容如下：

spring:
profiles:
active: dev

之后新建一个application-dev.yml文件，包含项目启动的端口，数据库的连接参数，以及mybatis的配置。

其内容如下：

# 1.项目启动的端口
server:
port: 8080
# 2.数据库连接参数
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://127.0.0.1:3306/user?serverTimezone=UTC&useSSL=false
username: root
password: 123
# 3.Mybatis的配置
mybatis:
# mybatis配置文件所在位置
config-location: classpath:mybatis-config.xml
# mapper配置文件所在位置
mapper-locations: classpath:mapper/*.xml
# 实体类所在的位置
type-aliases-package: com.example.area_mybatis.entity

三、Mybatis配置文件

在resources下新建mybatis-config.xml文件，其主要内容如下

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 配置全局属性 -->
<settings>
<!-- 使用jdbc的getGeneratedKeys获取数据库自增主键值 -->
<setting name="useGeneratedKeys" value="true"/>
<!-- 使用列标签替换列别名 默认:true -->
<setting name="useColumnLabel" value="true"/>
<!-- 开启驼峰命名转换:Table{create_time} -> Entity{createTime} -->
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
</configuration>

四、代码部分编写

代码包含了

• entity: 实体类的编写
• mapper:数据处理层
• service：业务逻辑层
• controller：控制器

1.entity/User

package com.example.area_mybatis.entity;
/**
* @author : codingchao
* @date : 2020-08-15 12:04
* @Description:
**/
public class User {
private int id;
private String name;
private String password;
private String number;
public User(String name, String password, String number) {
this.name = name;
this.password = password;
this.number = number;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
}

2.mapper/UserMapper

package com.example.area_mybatis.mapper;
import com.example.area_mybatis.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;
import java.util.List;
/**
* @author : codingchao
* @date : 2020-08-15 12:05
* @Description:
**/
@Repository
@Mapper
public interface UserMapper {
// 通过name查询
List<User> findUserByName(String name);
// 通过id查询
User findUserById(Integer id);
// 列出全部的user信息
public List<User> ListUser();
// 插入user信息
public int insertUser(User user);
// 删除user信息
public int delete(int id);
// 更新user信息
public int Update(User user);
}

3.service/UserService

package com.example.area_mybatis.service;
import com.example.area_mybatis.entity.User;
import java.util.List;
public interface UserService {
public List<User> findByName(String name);
public User findById(Integer id);
public List<User> ListUser();
public User insertUser(String name, String number,String password);
public int delete(Integer id);
public int Update(Integer id,String number);
}

4.service/impl/UserServiceImpl

package com.example.area_mybatis.service.impl;
import com.example.area_mybatis.entity.User;
import com.example.area_mybatis.mapper.UserMapper;
import com.example.area_mybatis.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
/**
* @author : codingchao
* @date : 2020-08-15 12:05
* @Description:
**/
@Service
public class UserServiceImpl implements UserService {
@Autowired
private UserMapper userMapper;
public List<User> findByName(String name){
return userMapper.findUserByName(name);
}
public User findById(Integer id){
return userMapper.findUserById(id);
}
public List<User> ListUser(){
return userMapper.ListUser();
}
public User insertUser(String name, String number,String password){
User user = new User(name,number,password);
userMapper.insertUser(user);
return user;
}
public int delete(Integer id){
return userMapper.delete(id);
}
public int Update(Integer id,String number){
User user = userMapper.findUserById(id);
user.setNumber(number);
return userMapper.Update(user);
}
}

5.在controller/CRUD

package com.example.area_mybatis.controller;
import com.example.area_mybatis.entity.User;
import com.example.area_mybatis.service.impl.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
/**
* @author : codingchao
* @date : 2020-08-15 12:05
* @Description:
**/
@RestController
@RequestMapping(value="/crud",method = {RequestMethod.GET,RequestMethod.POST})
public class CRUD {
@Autowired
private UserServiceImpl userService;
@GetMapping("/listUser")
public List<User> ListUser(){
return userService.ListUser();
}
@PostMapping(value="listUserByName")
public List<User> ListUserByNAME(@RequestParam("name") String name){
return userService.findByName(name);
}
@PostMapping(value="delete")
public String delete(@RequestParam("id") Integer id){
int result = userService.delete(id);
if (result >= 1){
return "删除成功";
}else{
return "删除失败";
}
}
@PostMapping(value = "insert")
public User insert(@RequestParam("name")String name,
@RequestParam("number")String number,
@RequestParam("password")String password){
return userService.insertUser(name,number,password);
}
@PostMapping(value = "update")
public String update(@RequestParam("id") Integer id,
@RequestParam("number")String number){
int result = userService.Update(id,number);
if (result >= 1){
return "修改成功";
}else{
return "修改失败";
}
}
}

五、数据库设计以及UserMapper数据库语句编写

数据库设计如下表所示

之后在resource下新建mapper文件夹，在其下新建UserMapper.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.area_mybatis.mapper.UserMapper">
<resultMap id="result" type="com.example.area_mybatis.entity.User">
<result property="name" column="name" />
<result property="password" column="password"/>
<result property="number" column="number" />
</resultMap>
<select id="ListUser" resultMap="result">
SELECT * FROM user
</select>
<select id="findUserByName" resultMap="result">
SELECT * FROM user where name=#{name}
</select>
<select id="findUserById" resultMap="result">
SELECT * FROM user where id=#{id}
</select>
<insert id="insertUser" parameterType="com.example.area_mybatis.entity.User"
keyProperty="id" useGeneratedKeys="true">
INSERT INTO user(
name,password,number
)
VALUES(
#{name},#{password},#{number}
)
</insert>
<update id="Update" parameterType="com.example.area_mybatis.entity.User">
update user
<set>
<if test="name != null">name=#{name},</if>
<if test="password != null">password=#{password},</if>
<if test="number != null">number=#{number}</if>
</set>
where id=#{id}
</update>
<delete id="delete" parameterType="com.example.area_mybatis.entity.User">
delete from user where id=#{id}
</delete>
</mapper>

六、postman测试

1.测试查询全部信息

http://localhost:8080/crud/listUser

2.通过名字来查询用户

http://localhost:8080/crud/listUserByName?name=A

3.新增用户

http://localhost:8080/crud/insert?name=B&number=202002&password=123456

4.删除用户

http://localhost:8080/crud/delete?id=3

那么，这期就结束了！！！

继续学习去！！！

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