1、Mybatis和MybatisPlus区别

　　Mybatis：ssm框架中，除了要写xml配置，还要写xml的sql文件，比如：usermapper.xml

　　MybatisPlus：基本上不用写一条SQL，如果业务层不复杂，完全不用业务层

　　MybatisPlus特性：无侵入，依赖少，防止SQL注入，通用CRUD，主键生成策略，代码生成，内置分页插件

　　　　主键生成策略：IdType.AUTO（自动）、IdType.INPUT（用户输入）、IdType.ID_WORKER（自动）、IdType.UUID（自动）

　　　　配置方法：主键ID上加注解，@TableId(value="ID",type="IdType.AUTO")，一般情况下推荐大家使用自动增长主键

2、配置文件（application.properties）　　

spring.datasource.driverClassName=com.mysql.jdbc.Driverspring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8spring.datasource.username=rootspring.datasource.password=rootspring.thymeleaf.mode=HTML5spring.thymeleaf.encoding=UTF-8spring.thymeleaf.content-type=text/html#开发时关闭缓存，不然没法看到实时页面spring.thymeleaf.cache=false

3、pom.xml中引入mybatis-plus的jar包

         
      
       com.baomidou
          
      
       mybatis-plus
          
      
       2.3.3
      
     

4、创建MybatisPlusConfig类

package com.cppdy.config;import javax.sql.DataSource;import org.apache.ibatis.mapping.DatabaseIdProvider;import org.apache.ibatis.plugin.Interceptor;import org.mybatis.spring.boot.autoconfigure.MybatisProperties;import org.mybatis.spring.boot.autoconfigure.SpringBootVFS;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.core.io.DefaultResourceLoader;import org.springframework.core.io.ResourceLoader;import org.springframework.util.ObjectUtils;import org.springframework.util.StringUtils;import com.baomidou.mybatisplus.MybatisConfiguration;import com.baomidou.mybatisplus.MybatisXMLLanguageDriver;import com.baomidou.mybatisplus.plugins.PaginationInterceptor;import com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean;@Configurationpublic class MybatisPlusConfig {    @Autowired    private DataSource dataSource;    @Autowired    private MybatisProperties properties;    @Autowired    private ResourceLoader resourceLoader = new DefaultResourceLoader();    @Autowired(required = false)    private Interceptor[] interceptors;    @Autowired(required = false)    private DatabaseIdProvider databaseldProvider;    /**     * mybatis-plus分页插件     */    @Bean    public PaginationInterceptor paginationInterceptor() {        PaginationInterceptor page = new PaginationInterceptor();        page.setDialectType("mysql");        return page;    }    /**     * 这里全部使用mybatis-autoconfigure已经自动加载的资源。不手动指定配置文件和mybatis-boot的配置文件同步     */    @Bean    public MybatisSqlSessionFactoryBean mybatisSqlSessionFactoryBean() {        MybatisSqlSessionFactoryBean mybatisPlus = new MybatisSqlSessionFactoryBean();        mybatisPlus.setDataSource(dataSource);        mybatisPlus.setVfs(SpringBootVFS.class);        if (StringUtils.hasText(this.properties.getConfigLocation())) {            mybatisPlus.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));        }        mybatisPlus.setConfiguration(properties.getConfiguration());        if (!ObjectUtils.isEmpty(this.interceptors)) {            mybatisPlus.setPlugins(this.interceptors);        }        MybatisConfiguration mc = new MybatisConfiguration();        mc.setDefaultScriptingLanguage(MybatisXMLLanguageDriver.class);        mybatisPlus.setConfiguration(mc);        if (this.databaseldProvider != null) {            mybatisPlus.setDatabaseIdProvider(this.databaseldProvider);        }        if (StringUtils.hasLength(this.properties.getTypeAliasesPackage())) {            mybatisPlus.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());        }        if (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {            mybatisPlus.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());        }        if (ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {            mybatisPlus.setMapperLocations(this.properties.resolveMapperLocations());        }        return mybatisPlus;    }}

5、UserMapper接口

package com.cppdy.mapper;import org.apache.ibatis.annotations.Mapper;import com.baomidou.mybatisplus.mapper.BaseMapper;import com.cppdy.entity.User;@Mapperpublic interface UserMapper extends BaseMapper
     
      {}
     

6、UserService接口

package com.cppdy.service;public interface UserService {    public void update(String username, int id);}

7、UserServiceImpl实现类

package com.cppdy.service.impl;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.transaction.annotation.Transactional;import com.cppdy.entity.User;import com.cppdy.mapper.UserMapper;import com.cppdy.service.UserService;@Servicepublic class UserServiceImpl implements UserService {    @Autowired    private UserMapper userMapper;    // 开启事务管理    @Transactional    public void update(String username, int id) {        User user = userMapper.selectById(id);        user.setUsername(username);        // 更新一条数据        userMapper.updateById(user);    }}

8、HelloWordController类

package com.cppdy.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.cppdy.entity.User;import com.cppdy.mapper.UserMapper;import com.cppdy.service.UserService;@RestControllerpublic class HelloWordController {    @Autowired    private UserMapper userMapper;    @Autowired    private UserService userService;    @RequestMapping("hello")    public String hello() {        return "HelloWord";    }    @RequestMapping("excep")    public String excep() {        int a = 2 / 0;        return "Hello Exception";    }    @RequestMapping("getUserById")    public Object getUserById(int id) {                return userMapper.selectById(id);    }    @RequestMapping("insert")    public void insert(String username) {        User user = new User();        user.setUsername(username);        userMapper.insert(user);    }    @RequestMapping("update")    public void update(String username, int id) {        userService.update(username, id);    }}