【Spring Boot 9】结合mybatis实现增删改查

「爱情、让人受尽委屈。」 2021-08-26 19:01 302阅读 0赞

# 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。

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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 #

![format_png 1][]

## 1、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>
    
    		
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-jdbc</artifactId>
    			<version>5.2.3.RELEASE</version>
    		</dependency>
    
    
    		
    		<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 #

![format_png 2][]

![format_png 3][]

如果不做更改，test connection不会成功。

# 四、注解版实现增删改查 #

## 1、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";
        }
    }

## 2、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();
    }

## 3、测试 ##

![format_png 4][]

# 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";
        }
    }

## 1、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);
    }

## 2、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>

## 3、application.yml ##

![format_png 5][]

## 4、测试 ##

![format_png 6][]

# 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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