重生之 SpringBoot3 入门保姆级学习（17、整合SSM）

4、数据访问
- 4.1 整合 ssm

4、数据访问

4.1 整合 ssm

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>3.3.0</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.zhong</groupId><artifactId>boot3-05-ssm</artifactId><version>0.0.1-SNAPSHOT</version><name>boot3-05-ssm</name><description>boot3-05-ssm</description><properties><java.version>17</java.version></properties><dependencies><!--SpringBoot Web 启动器--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--MySQL 驱动--><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency><!--MyBatis 依赖--><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>3.0.3</version></dependency><!--类注解插件--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><excludes><exclude><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></exclude></excludes></configuration></plugin></plugins></build></project>

application.properties

# 1、MySQL相关配置
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.type=com.zaxxer.hikari.HikariDataSource
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=123456# 2、整合 MyBatis
# mybatis.config-location 告诉 MyBatis 每个接口的 xml 在哪里
mybatis.mapper-locations=classpath:/mapper/*.xml
mybatis.configuration.map-underscore-to-camel-case=true

准备数据库

CREATE TABLE `t_user`
(`id` BIGINT(20) NOT NULL AUTO_INCREMENT COMMENT '编号',`login_name` VARCHAR(200) NULL DEFAULT NULL COMMENT '用户名称' COLLATE 'utf8_general_ci',	 `nick_name`  VARCHAR(200) NULL DEFAULT NULL COMMENT '用户昵称' COLLATE 'utf8_general_ci',	 `password`   VARCHAR(200) NULL DEFAULT NULL COMMENT '用户密码' COLLATE 'utf8_general_ci',PRIMARY KEY (`id`)	 
);
insert into t_user(login_name,nick_name,password) values ('xiaozhong','小钟','123456');
insert into t_user(login_name,nick_name,password) values ('xiaowang','小王','123456');

运行成功后请刷新数据库

添加 Tuser 实体类映射数据库字段

package com.zhong.ssm.bean;import lombok.Data;/*** @ClassName : Tuser* @Description :* @Author : zhx* @Date: 2024-06-02 17:40*/
@Data
public class TUser {private Long id;private String loginName;private String nickName;private String password;
}

安装插件 MyBatisX

写 UserMapper 接口

package com.zhong.ssm.bean.mapper;/*** @ClassName : UserMapper* @Description :* @Author : zhx* @Date: 2024-06-02 17:47*/
public interface UserMapper {}

按键盘 Alt + Enter 选择 [MybatisX] Generate of xml 选择当前项目的 resource 目录下的 mapper 文件夹点击确定

自动生成了对应的 xml 文件

快速生成：新建方法 getUserById 按键盘 Alt + Enter 直接回车

package com.zhong.ssm.bean.mapper;import com.zhong.ssm.bean.TUser;
import org.apache.ibatis.annotations.Param;/*** @ClassName : UserMapper* @Description :* @Author : zhx* @Date: 2024-06-02 17:47*/
public interface UserMapper {/*** 1、每个方法都在 mapper 文件有一个 sql 标签对应的* 2、所有参数都应该用 @Param(name) 进行签名 SQL 中才可用 #{name} 取值* @param id* @return*/TUser getUserById(@Param("id") Long id);
}

添加查询语句

<?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.zhong.ssm.bean.mapper.UserMapper"><select id="getUserById" resultType="com.zhong.ssm.bean.TUser">select * from t_user where id=#{id}</select>
</mapper>

添加包扫描路径

package com.zhong.ssm;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@MapperScan(basePackages = "com.zhong.ssm.bean.mapper")
@SpringBootApplication
public class Boot305SsmApplication {public static void main(String[] args) {SpringApplication.run(Boot305SsmApplication.class, args);}}

添加 controller

package com.zhong.ssm.controller;import com.zhong.ssm.bean.TUser;
import com.zhong.ssm.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;/*** @ClassName : UserController* @Description :* @Author : zhx* @Date: 2024-06-02 19:15*/
@RestController
public class UserController {@AutowiredUserMapper userMapper;@GetMapping("/user/{id}")public TUser getUser(@PathVariable("id") Long id) {return userMapper.getUserById(id);}
}