Spring Boot（九）：结合mybatis实现增删改查

一、前言

最近在跟着视频做码匠社区项目，视频中连接H2数据库，但是我这个社区版的IDEA无法集成H2，暂时还未找到解决办法。

因此想到了之前练习的连接MySQL，为了能继续下去，只能先这样了，以后找到解决办法再改成H2吧！

二、项目架构

pom.xml

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.2.4.RELEASE</version>
		<relativePath/>
	</parent>
	<groupId>life.majiang.community</groupId>
	<artifactId>community</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>community</name>
	<description>community</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
		</dependency>

		<!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-jdbc</artifactId>
			<version>5.2.3.RELEASE</version>
		</dependency>


		<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
		<dependency>
			<groupId>org.mybatis</groupId>
			<artifactId>mybatis</artifactId>
			<version>3.5.4</version>
		</dependency>

		<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>
			<version>8.0.11</version>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

三、springboot集成MySQL

如果不做更改，test connection不会成功。

四、注解版实现增删改查

我习惯从controller开写

package life.majiang.community.controller;

import life.majiang.community.bean.User;
import life.majiang.community.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

@Controller
public class UserController {
    @Autowired
    UserMapper userMapper;
    @Autowired
    User user;

    @GetMapping("/getUserById")
    public String getUserById(@RequestParam(name="id") String id){
        System.out.println(userMapper.getUserById(id).name);
        return "index";
    }

    @GetMapping("/getUsers")
    public String getUsers(){
        return "index";
    }

    @GetMapping("/insertUser")
    public String insertUser(@RequestParam(name="id") String id,@RequestParam(name="name") String name,@RequestParam(name="password") String password){
        user.setId(id);
        user.setName(name);
        user.setPassword(password);
        userMapper.insertUser(user);
        return "index";
    }
}

UserMapper

package life.majiang.community.mapper;

import life.majiang.community.bean.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {
    @Select("select * from user where id=#{id}")
    public User getUserById(String id);

    @Insert("insert into user(ID,name,password) values (#{id},#{name},#{password})")
    public void insertUser(User user);

    @Select("select * from user")
    public User getUsers();
}

测试

五、配置实现增删改查

package life.majiang.community.controller;

import life.majiang.community.bean.User;
import life.majiang.community.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

@Controller
public class UserController {
    @Autowired
    UserMapper userMapper;
    @Autowired
    User user;

    @GetMapping("/getUserById2")
    public String getUserById2(@RequestParam(name="id") String id){
        System.out.println(userMapper.getUserById2(id).name);
        return "index";
    }

    @GetMapping("/insertUser2")
    public String insertUser2(@RequestParam(name="id") String id,@RequestParam(name="name") String name,@RequestParam(name="password") String password){
        user.setId(id);
        user.setName(name);
        user.setPassword(password);
        userMapper.insertUser2(user);
        return "index";
    }

    @GetMapping("/deleteUserById")
    public String deleteUserById(@RequestParam(name="id") String id){
        userMapper.deleteUserById(id);
        return "index";
    }
}

UserMapper

package life.majiang.community.mapper;

import life.majiang.community.bean.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {
    public User getUserById2(String id);
    public void insertUser2(User user);
    public void deleteUserById(String id);
}

UserMapper.xml

<?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="life.majiang.community.mapper.UserMapper">
    <select id="getUserById2" resultType="life.majiang.community.bean.User">
        SELECT * FROM user WHERE id=#{id};
    </select>
   <insert id="insertUser2">
      insert into user(ID,name,password) values (#{id},#{name},#{password});
   </insert>
    <delete id="deleteUserById">
        delete from user where id=#{id};
    </delete>
</mapper>

application.yml

测试

六、总结

springboot通过mybatis实现增删改查还是挺简单的，但也有很多问题需要注意，比如@MapperScan，application.yml的配置，驼峰的设置等等。

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