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先发结构图
首先需要先把dao的相关依赖导入到pom.xml,我的mysql是8版本此处有坑，mysql8的url连接有改变，根据自己mysql版本选择。
<dependency> <groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.2.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.2.8</version>
</dependency>
以数据库表Users为例
（1）、users表
/*
Navicat Premium Data Transfer
Source Server : Mysql
Source Server Type : MySQL
Source Server Version : 80026
Source Host : localhost:3306
Source Schema : tsingby
Target Server Type : MySQL
Target Server Version : 80026
File Encoding : 65001
Date: 23/12/2021 18:07:15
*/
-- ----------------------------
-- Table structure for users
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
`userId` int NOT NULL AUTO_INCREMENT,
`username` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '账号',
`password` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '密码',
`mail` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '邮箱',
PRIMARY KEY (`userId`) USING BTREE,
INDEX `mail`(`mail`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;
SET FOREIGN_KEY_CHECKS = 1;
（2）、pom.xml
的build—> plugins 标签引入如下plugin标签
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<!--插件设置-->
<configuration>
<!--自动生成配置 如果名字是generatorConfig.xml并且直接放在resources文件夹下可以省略配置-->
<!--<configurationFile>src/main/resources/generatorConfig.xml</configurationFile>-->
<configurationFile>${basedir}/src/main/resources/config/generatorConfig.xml</configurationFile>
<!--允许移动生成的文件-->
<verbose>true</verbose>
<!--启用覆盖-->
<overwrite>true</overwrite>
</configuration>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.27</version>
</dependency>
</dependencies>
</plugin>
*注意
需要在plugin引入你的和mysql版本一致的mysql-connector-java，我mysql是8版本的，所以引用的是<version>8.0.27</version>
之后刷新maven，出现下面的插件就是成功了
完整的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>2.6.2</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.mqb</groupId>
<artifactId>springboot02</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot02</name>
<description>springboot02</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- mapper-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.2.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.2.8</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
</dependencies>
<build>
<!-- 如果不添加此节点mybatis的mapper.xml文件都会被漏掉。 -->
<resources>
<!-- 一定要添加，以防资源找不到-->
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
<include>**/*.yaml</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
<include>**/*.yaml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<!--插件设置-->
<configuration>
<!--自动生成配置 如果名字是generatorConfig.xml并且直接放在resources文件夹下可以省略配置-->
<!--<configurationFile>src/main/resources/generatorConfig.xml</configurationFile>-->
<configurationFile>${basedir}/src/main/resources/config/generatorConfig.xml</configurationFile>
<!--允许移动生成的文件-->
<verbose>true</verbose>
<!--启用覆盖-->
<overwrite>true</overwrite>
</configuration>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.27</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>
（3）、编写配置文件
generatorConfig.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
"http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<!-- 配置生成器 -->
<generatorConfiguration>
<!--<classPathEntry location="D:\java\apache-maven-3.8.1-bin\apache-maven-3.8.1\resources\mysql\mysql-connector-java\8.0.27\mysql-connector-java-8.0.27.jar"/>-->
<context id="DB2Tables" targetRuntime="MyBatis3">
<commentGenerator>
<property name="suppressDate" value="true"/>
<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
<property name="suppressAllComments" value="true"/>
</commentGenerator>
<!-- 数据库链接URL，用户名、密码 -->
<jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/tsingby?serverTimezone=GMT%2B8&useSSL=false"
userId="root" password="root">
<!-- 仅仅查询当前库的表，不去查询其他库 -->
<property name="nullCatalogMeansCurrent" value="true"/>
<property name="remarksReporting" value="true"/>
</jdbcConnection>
<!-- 类型转换 -->
<javaTypeResolver>
<!-- 是否使用BigDecimals，false可自动转化以下类型(Long Integer Short等) -->
<property name="forceBigDecimals" value="false"/>
</javaTypeResolver>
<!-- 生成模型的包名和位置
targetPackage : 生成User实体类存放的文件夹
-->
<javaModelGenerator targetPackage="com.mqb.springboot02.pojo" targetProject="src/main/java">
<!-- <javaModelGenerator targetPackage="com.mqb.springboot02.pojo" targetProject=".\src\main\java">-->
<!--enableSubPackages:如果true，MBG会根据catalog和schema来生成子包。
如果false就会直接用targetPackage属性。默认为false。-->
<property name="enableSubPackages" value="true"/>
<!--trimStrings:是否对数据库查询结果进行trim操作，
如果设置为true就会生成类似这样
public void setUsername(String username) {
this.username = username == null ? null : username.trim();
}的setter方法。默认值为false。-->
<property name="trimStrings" value="true"/>
</javaModelGenerator>
<!-- targetPackage：生成mapper.xml映射文件的包名-->
<!-- 接口和mapper映射文件可以分开放，也可以放一起，本例放一起-->
<sqlMapGenerator targetPackage="com.mqb.springboot02.mapper" targetProject="src/main/java">
<!-- 接口和mapper映射文件分开放-->
<!-- <sqlMapGenerator targetPackage="mappers" targetProject="src/main/resources">-->
<property name="enableSubPackages" value="true"/>
</sqlMapGenerator>
<!-- targetPackage：生成Mapper也就是dao接口的包名 -->
<!-- 客户端代码，生成易于使用的针对Model对象和XML配置文件 的代码
type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper对象
type="MIXEDMAPPER",生成基于注解的Java Model 和相应的Mapper对象
type="XMLMAPPER",生成SQLMap XML文件和独立的Mapper接口
-->
<javaClientGenerator type="XMLMAPPER" targetPackage="com.mqb.springboot02.mapper" targetProject="src/main/java">
<property name="enableSubPackages" value="true"/>
</javaClientGenerator>
<!-- 要生成的表 tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
<table tableName="users" domainObjectName="User" enableCountByExample="false"
enableUpdateByExample="false" enableDeleteByExample="false"
enableSelectByExample="false" selectByExampleQueryId="false">
<!-- 是否使用实际列名-->
<!-- true MyBatis Generator会使用数据库中实际的字段名字作为生成的实体类的属性名。
false(默认值)。如果设置为false,则MyBatis Generator会将数据库中实际的字段名字转换为驼峰式风格作为生成的实体类的属性名。-->
<property name="useActualColumnNames" value="false"/>
<!-- 数据库表主键 -->
<generatedKey column="userId" sqlStatement="Mysql" identity="true"/>
</table>
</context>
</generatorConfiguration>
application.yaml
spring:
datasource:
url: jdbc:mysql://localhost:3306/tsingby?serverTimezone=GMT%2B8&useSSL=false
username: root
password: root
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
# 全局的映射，不用在xml文件写实体类的全路径
type-aliases-package: com.mqb.springboot02.pojo
点击mybatis-generator:generate插件，查看是否生成mapper和映射文件
多出来的文件都是自动生成的，我没手动加任何文件
（4）、查看生成的文件
User.java
package com.mqb.springboot02.pojo;
import org.springframework.context.annotation.Bean;
public class User {
private Integer userid;
private String username;
private String password;
private String mail;
public Integer getUserid() {
return userid;
}
public void setUserid(Integer userid) {
this.userid = userid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username == null ? null : username.trim();
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password == null ? null : password.trim();
}
public String getMail() {
return mail;
}
public void setMail(String mail) {
this.mail = mail == null ? null : mail.trim();
}
}
UserMapper.java接口
package com.mqb.springboot02.mapper;
import com.mqb.springboot02.pojo.User;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;
import org.springframework.web.bind.annotation.ResponseBody;
@Repository
public interface UserMapper {
int deleteByPrimaryKey(Integer userid);
int insert(User record);
int insertSelective(User record);
User selectByPrimaryKey(Integer userid);
int updateByPrimaryKeySelective(User record);
int updateByPrimaryKey(User record);
}
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="com.mqb.springboot02.mapper.UserMapper" >
<resultMap id="BaseResultMap" type="com.mqb.springboot02.pojo.User" >
<id column="userId" property="userid" jdbcType="INTEGER" />
<result column="username" property="username" jdbcType="VARCHAR" />
<result column="password" property="password" jdbcType="VARCHAR" />
<result column="mail" property="mail" jdbcType="VARCHAR" />
</resultMap>
<sql id="Base_Column_List" >
userId, username, password, mail
</sql>
<select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
select
<include refid="Base_Column_List" />
from users
where userId = #{userid,jdbcType=INTEGER}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
delete from users
where userId = #{userid,jdbcType=INTEGER}
</delete>
<insert id="insert" parameterType="com.mqb.springboot02.pojo.User" >
<selectKey resultType="java.lang.Integer" keyProperty="userid" order="AFTER" >
SELECT LAST_INSERT_ID()
</selectKey>
insert into users (username, password, mail
)
values (#{username,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{mail,jdbcType=VARCHAR}
)
</insert>
<insert id="insertSelective" parameterType="com.mqb.springboot02.pojo.User" >
<selectKey resultType="java.lang.Integer" keyProperty="userid" order="AFTER" >
SELECT LAST_INSERT_ID()
</selectKey>
insert into users
<trim prefix="(" suffix=")" suffixOverrides="," >
<if test="username != null" >
username,
</if>
<if test="password != null" >
password,
</if>
<if test="mail != null" >
mail,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides="," >
<if test="username != null" >
#{username,jdbcType=VARCHAR},
</if>
<if test="password != null" >
#{password,jdbcType=VARCHAR},
</if>
<if test="mail != null" >
#{mail,jdbcType=VARCHAR},
</if>
</trim>
</insert>
<update id="updateByPrimaryKeySelective" parameterType="com.mqb.springboot02.pojo.User" >
update users
<set >
<if test="username != null" >
username = #{username,jdbcType=VARCHAR},
</if>
<if test="password != null" >
password = #{password,jdbcType=VARCHAR},
</if>
<if test="mail != null" >
mail = #{mail,jdbcType=VARCHAR},
</if>
</set>
where userId = #{userid,jdbcType=INTEGER}
</update>
<update id="updateByPrimaryKey" parameterType="com.mqb.springboot02.pojo.User" >
update users
set username = #{username,jdbcType=VARCHAR},
password = #{password,jdbcType=VARCHAR},
mail = #{mail,jdbcType=VARCHAR}
where userId = #{userid,jdbcType=INTEGER}
</update>
</mapper>
（4）、测试
-
在UserMapper.java类上添加@Repository注解
-
编写Userservice接口,只使用一个方法测试
package com.mqb.springboot02.userService; import com.mqb.springboot02.pojo.User; public interface UserService { User selectByPrimaryKey(Integer userid); } -
UserServiceIMmpl实现类
package com.mqb.springboot02.userService.userServiceImpl; import com.mqb.springboot02.mapper.UserMapper; import com.mqb.springboot02.pojo.User; import com.mqb.springboot02.userService.UserService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class UserServiceImpl implements UserService { @Autowired UserMapper userMapper; @Override public User selectByPrimaryKey(Integer userid) { return userMapper.selectByPrimaryKey(userid); } } -
UserController
package com.mqb.springboot02.controller; import com.mqb.springboot02.pojo.User; import com.mqb.springboot02.userService.UserService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; @Controller @ResponseBody public class UserController { @Autowired UserService userService; @RequestMapping("/test") public User test(){ return userService.selectByPrimaryKey(1); } }在启动主程序添加@MapperScan()注解，扫描mapper
package com.mqb.springboot02; import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @MapperScan("com.mqb.springboot02.mapper") @SpringBootApplication public class Springboot02Application { public static void main(String[] args) { SpringApplication.run(Springboot02Application.class, args); } }放上目录结构
启动springboot项目，浏览器访问localhost:8080,出现信息，成功
