SpringBoot整合MybatisPlus＋单表CRUD(详解)

1 创建测试表

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` bigint(20) NOT NULL,
  `username` varchar(20) NOT NULL,
  `password` varchar(20) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2 创建SpringBoot项目

创建时用阿里镜像服务:https://start.aliyun.com 快速创建项目

选择Lombok插件 web模块和mySql驱动

3 配置

pom.xml

 		<!--mp-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>
        <!--mp代码生成器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.2.0</version>
        </dependency>

application.yml
说明
mapper-locations指的是Mapper的路径
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl指的是执行的sql语句打印到控制台
注意：数据源使用自己的

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mp?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai
    username: 
    password: 
mybatis-plus:
  mapper-locations: classpath*:/mapper/**Mapper.xml
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
server:
  port: 8082

MybatisPlusConfig
配置mapper路径和分页

package com.yxx.testmp.config;

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@EnableTransactionManagement
@MapperScan("com.yxx.testmp.mapper")
public class MybatisPlusConfig {

    @Bean
    public PaginationInterceptor paginationInterceptor() {
        PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
        return paginationInterceptor;
    }
}

代码生成器 在启动类TestmpApplication同级目录下创建
注意：数据源使用自己的

package com.yxx.testmp;

import com.baomidou.mybatisplus.core.exceptions.MybatisPlusException;
import com.baomidou.mybatisplus.core.toolkit.StringPool;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.InjectionConfig;
import com.baomidou.mybatisplus.generator.config.*;
import com.baomidou.mybatisplus.generator.config.po.TableInfo;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;
import com.baomidou.mybatisplus.generator.engine.FreemarkerTemplateEngine;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

// 演示例子，执行 main 方法控制台输入模块表名回车自动生成对应项目目录中
public class CodeGenerator {

    /**
     * <p>
     * 读取控制台内容
     * </p>
     */
    public static String scanner(String tip) {
        Scanner scanner = new Scanner(System.in);
        StringBuilder help = new StringBuilder();
        help.append("请输入" + tip + "：");
        System.out.println(help.toString());
        if (scanner.hasNext()) {
            String ipt = scanner.next();
            if (StringUtils.isNotEmpty(ipt)) {
                return ipt;
            }
        }
        throw new MybatisPlusException("请输入正确的" + tip + "！");
    }

    public static void main(String[] args) {
        // 代码生成器
        AutoGenerator mpg = new AutoGenerator();

        // 全局配置
        GlobalConfig gc = new GlobalConfig();
        String projectPath = System.getProperty("user.dir");
        gc.setOutputDir(projectPath + "/src/main/java");
//        gc.setOutputDir("D:\\test");
        gc.setAuthor("yxx");
        gc.setOpen(false);
        gc.setSwagger2(true); //实体属性 Swagger2 注解
        gc.setServiceName("%sService");
        mpg.setGlobalConfig(gc);

        // 数据源配置
        DataSourceConfig dsc = new DataSourceConfig();
        dsc.setUrl("jdbc:mysql://localhost:3306/mp?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=UTC");
        // dsc.setSchemaName("public");
        dsc.setDriverName("com.mysql.cj.jdbc.Driver");
        dsc.setUsername("");
        dsc.setPassword("");
        mpg.setDataSource(dsc);

        // 包配置
        PackageConfig pc = new PackageConfig();
        pc.setModuleName(null);
        pc.setParent("com.yxx.testmp");
        mpg.setPackageInfo(pc);

        // 自定义配置
        InjectionConfig cfg = new InjectionConfig() {
            @Override
            public void initMap() {
                // to do nothing
            }
        };

        // 如果模板引擎是 freemarker
        String templatePath = "/templates/mapper.xml.ftl";
        // 如果模板引擎是 velocity
        // String templatePath = "/templates/mapper.xml.vm";

        // 自定义输出配置
        List<FileOutConfig> focList = new ArrayList<>();
        // 自定义配置会被优先输出
        focList.add(new FileOutConfig(templatePath) {
            @Override
            public String outputFile(TableInfo tableInfo) {
                // 自定义输出文件名 ， 如果你 Entity 设置了前后缀、此处注意 xml 的名称会跟着发生变化！！
                return projectPath + "/src/main/resources/mapper/"
                        + "/" + tableInfo.getEntityName() + "Mapper" + StringPool.DOT_XML;
            }
        });

        cfg.setFileOutConfigList(focList);
        mpg.setCfg(cfg);

        // 配置模板
        TemplateConfig templateConfig = new TemplateConfig();

        templateConfig.setXml(null);
        mpg.setTemplate(templateConfig);

        // 策略配置
        StrategyConfig strategy = new StrategyConfig();
        strategy.setNaming(NamingStrategy.underline_to_camel);
        strategy.setColumnNaming(NamingStrategy.underline_to_camel);
        strategy.setEntityLombokModel(true);
        strategy.setRestControllerStyle(true);
        strategy.setInclude(scanner("表名，多个英文逗号分割").split(","));
        strategy.setControllerMappingHyphenStyle(true);
        mpg.setStrategy(strategy);
        mpg.setTemplateEngine(new FreemarkerTemplateEngine());
        mpg.execute();
    }
}

3 启动逆向工程创建项目基础框架

运行CodeGenerator的main方法即可

自动生成了包结构等等

4 单表CRUD

增

/*
  * 增加
  * */
  @Test
  public void testInsert(){
    User user = new User();
    user.setUsername("lal");
    user.setPassword("lal");
    user.setName("lal");
    user.setAge(15);
    user.setEmail("lalal");
    int insert = userMapper.insert(user);//insert表示受影响的行数 不是自增的id
    long id=user.getId(); //执行成功之后会回传一个自增的id
  }

更新

/*更新
  * */
  @Test
  public void testUpdateById(){
    User user = new User();
    user.setId(1l);
    user.setUsername("1号");
    int update = userMapper.updateById(user);
  }
  @Test
  public void testUpdate(){
    //使用QueryWrapper更新
    User user = new User();
    user.setUsername("2号");
    QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.eq("username","lal");
    int update1 = userMapper.update(user, queryWrapper);

    //使用QueryWrapper更新
    UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
    updateWrapper.set("age",16).eq("age",1);
    int update2 = userMapper.update(null, updateWrapper);
  }

删除

/*删除
  * */
  @Test
  public void testDeleteById(){
    userMapper.deleteById(3l);
  }
  @Test
  public void testDeleteByMap(){
    HashMap<String, Object> map = new HashMap<>();
    map.put("username","lal");
    map.put("password","lal");
    userMapper.deleteByMap(map);
  }

  @Test
  public void testDelete(){
    //方法1
    /*QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.eq("username","lal").eq("password","lal");*/
    //方法2
    User user = new User();
    user.setUsername("lal");
    user.setPassword("lal");
    QueryWrapper<User> queryWrapper = new QueryWrapper<>(user);
    userMapper.delete(queryWrapper);
  }
  @Test
  public void testDeleteBatchIds(){
    userMapper.deleteBatchIds(Arrays.asList(1l,2l));
  }

查询

 /*查询
  * */
  @Test
  public void testSelectById(){
    User user = userMapper.selectById(1l);
  }
  @Test
  public void testSelectBatchIds(){
    userMapper.selectBatchIds(Arrays.asList(1l,2l));
  }

  @Test
  public void testSelectOne(){
    QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.eq("username","1号");
    User user = userMapper.selectOne(queryWrapper);
  }

  @Test
  public void testSelectCount(){
    QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.gt("age","10");
    Integer integer = userMapper.selectCount(queryWrapper);
  }

  @Test
  public void testSelectList(){
    QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.like("username","号");
    List<User> users = userMapper.selectList(queryWrapper);
    System.out.println(users);
  }

  @Test
  public void testSelectPage(){
    Page<User> userPage = new Page<>(1,5);
    QueryWrapper<User> queryWrapper = new QueryWrapper<>();
    queryWrapper.like("username","号");
    IPage<User> userIPage = userMapper.selectPage(userPage,queryWrapper);
    System.out.println("总条数"+userIPage.getTotal());
    System.out.println("总页数"+userIPage.getPages());
    System.out.println("当前页"+userIPage.getCurrent());
    List<User> records = userIPage.getRecords();
  }

5 一些小细节

在实体类的主键上加上@TableId(type=IdType.AUTO)使得程序逻辑和数据库逻辑一致

mapper注入爆红的话给Mapper加上@Repository注解就行了（这不是必须的 因为我们在配置文件中已经制定了Mapper的路径 这里的爆红是ide的问题并不影响的 ）

本文地址：https://blog.csdn.net/qq_44173974/article/details/107351933