MyBatisPlus

一、简介

1、说明

• MyBatis-Plus（简称 MP）是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。

2、特性

• 无侵入：只做增强不做改变，引入它不会对现有工程产生影响，如丝般顺滑
• 损耗小：启动即会自动注入基本 CURD，性能基本无损耗，直接面向对象操作
• 强大的 CRUD 操作：内置通用 Mapper、通用 Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求
• 支持 Lambda 形式调用：通过 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错
• 支持主键自动生成：支持多达 4 种主键策略（内含分布式唯一 ID 生成器 - Sequence），可自由配置，完美解决主键问题
• 支持 ActiveRecord 模式：支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可进行强大的 CRUD 操作
• 支持自定义全局通用操作：支持全局通用方法注入（ Write once, use anywhere ）
• 内置代码生成器：采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码，支持模板引擎，更有超多自定义配置等您来使用
• 内置分页插件：基于 MyBatis 物理分页，开发者无需关心具体操作，配置好插件之后，写分页等同于普通 List 查询
• 分页插件支持多种数据库：支持 MySQL、MariaDB、Oracle、DB2、H2、HSQL、SQLite、Postgre、SQLServer 等多种数据库
• 内置性能分析插件：可输出 Sql 语句以及其执行时间，建议开发测试时启用该功能，能快速揪出慢查询
• 内置全局拦截插件：提供全表 delete 、 update 操作智能分析阻断，也可自定义拦截规则，预防误操作

二、MP和Spring的集成

1、创建普通Maven工程

2、加入依赖

<properties>
    <mybatisplus.version>3.2.0mybatisplus.version>
    <spring.version>4.3.9.RELEASEspring.version>
    <mysql.version>5.1.39mysql.version>
    
    <log4j.version>1.2.17log4j.version>
    <lombok.version>1.18.10lombok.version>
properties>

<dependencies>
    
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-aspectsartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-aopartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-contextartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-coreartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-expressionartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-ormartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-jdbcartifactId>
        <version>${spring.version}version>
    dependency>
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-txartifactId>
        <version>${spring.version}version>
    dependency>
    
    <dependency>
        <groupId>mysqlgroupId>
        <artifactId>mysql-connector-javaartifactId>
        <version>${mysql.version}version>
    dependency>
    
    <dependency>
        <groupId>log4jgroupId>
        <artifactId>log4jartifactId>
        <version>${log4j.version}version>
    dependency>
    
    <dependency>
        <groupId>com.baomidougroupId>
        <artifactId>mybatis-plusartifactId>
        <version>${mybatisplus.version}version>
    dependency>
    
    <dependency>
        <groupId>org.projectlombokgroupId>
        <artifactId>lombokartifactId>
        <version>${lombok.version}version>
        <optional>trueoptional>
    dependency>
dependencies>

3、创建实体类,并实现Serializable接口

@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
@TableName(value = "dept")//与数据库表映射
public class Dept implements Serializable {
    @TableId(value="pid")//表示主键，带参数表示将属性和表字段映射，若属性和字段名一致可以不加
    private Integer id;
    private String pname;
    @TableField(value = "premark")//若属性名和表字段名一致可以不加
    private String premark;
}

4、创建Mapper类，继承BaseMapper接口

public interface DeptMapper extends BaseMapper<Dept> {
}

5、创建log4j.properties

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# MyBatis logging configuration...
log4j.logger.org.mybatis.example.BlogMapper=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

6、创建XXXMapper.xml

• 作用：mp只能操作单表，要是多表，则可以在 mapper.xml中拓展

  
  
  <mapper namespace="com.sxt.mapper.UserMapper">
  	
  mapper>
  

  ​

7、配置applicationContext.xml文件

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd" default-autowire="byName">
    
    <context:component-scan base-package="com.itan.service"/>
    
    <context:property-placeholder location="classpath:db.properties"/>
    
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/test"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    bean>
    
    <bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="globalConfig" ref="globalConfig"/>
        
        <property name="mapperLocations">
            <array>
                <value>classpath:mapper/*Mapper.xmlvalue>
            array>
        property>
        
        <property name="plugins">
            <array>
                <bean class="com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor">bean>
            array>
        property>
    bean>
    
    <bean id="globalConfig" class="com.baomidou.mybatisplus.core.config.GlobalConfig">
        
        <property name="dbConfig" ref="dbConfig">property>
    bean>
    <bean id="dbConfig" class="com.baomidou.mybatisplus.core.config.GlobalConfig.DbConfig">
        <property name="idType" value="AUTO"/>
    bean>
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        
        <property name="basePackage" value="com.itan.mapper"/>
        
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    bean>
beans>

8、测试

• 主方法

  public static void main(String[] args) {
    ApplicationContext context=new 					ClassPathXmlApplicationContext("classpath:applicationContext.xml");
    DeptMapper deptMapper=context.getBean(DeptMapper.class);
    //addDept(deptMapper);
    //uppDept(deptMapper);
    //delDept(deptMapper);
    //queryDept(deptMapper,"销售");
  }
  

• 添加

  public static void addDept(DeptMapper deptMapper){
    	deptMapper.insert(new Dept(null, "人事部", "123456"));
  }
  

• 删除

  public static void delDept(DeptMapper deptMapper){
      //1、根据主键删除，相当于DELETE FROM dept WHERE pid=?
      deptMapper.deleteById(126);
      //2、批量删除，相当于使用DELETE FROM dept WHERE pid IN ( ? , ? )
      Collection<Serializable> idList = new ArrayList<Serializable>();
      idList.add(135);
      idList.add(136);
      deptMapper.deleteBatchIds(idList);
      //3、多条件删除，相当于DELETE FROM dept WHERE pname = ? AND pid = ?
      Map<String,Object> map=new HashMap<>();
      map.put("pid",131);
      map.put("pname","人事部");
      deptMapper.deleteByMap(map);
      //4、查询删除,先查询出来再删除
      Wrapper<Dept> wrapper=new QueryWrapper<>();
      ((QueryWrapper<Dept>) wrapper).between("pid",131,132);
      deptMapper.delete(wrapper);
  }
  

• 修改

  public static void uppDept(DeptMapper deptMapper){
    //1、根据主键修改
    deptMapper.updateById(new Dept(125, "人事部", "小美女多"));
    //2、多条件修改：eq(表的字段，要修改的值)
    //相当于：UPDATE dept SET premark=?, pname=? WHERE (pname = ? AND premark = ?)
    UpdateWrapper<Dept> updateWrapper=new UpdateWrapper<>();
    updateWrapper.eq("pname","销售");
    updateWrapper.eq("premark","销售多");
    //3、between(表的字段,条件1,条件2)：修改在条件1到条件2之间的数据
    //相当于：UPDATE dept  SET premark=?, pname=? WHERE (id BETWEEN ? AND ?)
    updateWrapper.between("pid",125,128);
    deptMapper.update(new Dept(null, "销售", "销售人才多"),updateWrapper);
  }
  

• 查询（注：使用分页查询要配置分页插件）

  public static void queryDept(DeptMapper deptMapper,String pname){
      //1、根据主键id查询
      Dept dept = deptMapper.selectById(130);
      System.out.println(dept);
      //2、根据主键id使用in关键字的sql查询
      Collection<Serializable> idList = new ArrayList<Serializable>();
      idList.add(133);
      idList.add(134);
      List<Dept> depts = deptMapper.selectBatchIds(idList);
      //3、多条件使用and关键字的sql查询
      Map<String,Object> map=new HashMap<>();
      map.put("pid",129);
      map.put("premark","456");
      List<Dept> depts = deptMapper.selectByMap(map);
      //4、查询所有条数
      Integer integer = deptMapper.selectCount(null);
      //5、带条件的查询
      Wrapper<Dept> wrapper=new QueryWrapper<>();
      ((QueryWrapper<Dept>) wrapper).like(pname!=null,"pname",pname);
      Integer integer = deptMapper.selectCount(wrapper);
      //6、不带条件的分页
      IPage<Dept> page = new Page<>(1,5);
      deptMapper.selectPage(page,null);
      long total = page.getTotal();//总条数
      System.out.println("总条数:"+total);
      List<Dept> depts = page.getRecords();//所有的数据
      for(Dept d:depts){
        System.out.println(d);
      }
  }
  

三、MP和SpringBoot集成

1、创建一个springboot项目

• 勾选：Spring Web、Lombok、JDBC API、MySQL Driver

2、添加MyBatisPlus依赖

<dependency>
    <groupId>com.baomidougroupId>
    <artifactId>mybatis-plus-boot-starterartifactId>
    <version>3.2.0version>
dependency>

3、创建实体类，并实现Seriaializable接口

@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
@TableName(value = "dept")//与数据库表映射
public class Dept implements Serializable {
    @TableId(value="pid")//表示主键
    private Integer id;
    private String pname;
    @TableField(value = "premark")//若属性名和表字段名一致可以不加
    private String premark;
}

4、创建Mapper类，继承BaseMapper接口

• 注：要加@Mapper 注解或者在启动类上加@MapperScan(basePackage={"com.itan.mapper"})

  @Mapper
  public interface DeptMapper extends BaseMapper<Dept> {
  }
  

5、配置application.yml文件

#配置数据源
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useSSL=true&serverTimezone=UTC
    username: root
    password: 123456
    #指明数据源用哪个
    type: org.springframework.jdbc.datasource.DriverManagerDataSource
#配置mybatisplus
mybatis-plus:
  #扫描mapper文件
  mapper-locations:
    - classpath:mapper/*Mapper.xml
  #配置主键自增
  global-config:
    db-config:
      id-type: auto
    banner: true
  #打印sql语句
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

6、要是使用分页，则需要配置分页配置文件

@Configuration
@ConditionalOnClass(value = {PaginationInterceptor.class})
public class MybatisPlusConfig {
    @Bean
    public PaginationInterceptor myBatisPlus(){
        return new PaginationInterceptor();
    }
}

7、测试

@Test
void pageDept(){
    IPage<Dept> page = new Page<>(1, 5);
    deptMapper.selectPage(page,null);
    List<Dept> lis = page.getRecords();
    for (Dept d:lis){
      	System.out.println(d);
    }
    System.out.println("总数："+page.getTotal());
}

四、MP-AR模式开发

1、复制上面的项目

2、修改实体类

@Data
@EqualsAndHashCode(callSuper = false)
@AllArgsConstructor
@NoArgsConstructor
@ToString
@TableName(value = "dept")//与数据库表映射
public class Dept extends Model<Dept> implements Serializable {
    @TableId(value="pid")//表示主键
    private Integer id;
    private String pname;
    @TableField(value = "premark")//若属性名和表字段名一致可以不加
    private String premark;
  	@TableField(exist = false)//当查询结果中没有这个字段可以用这个方法忽略掉这个属性
  	private String sex;
}

3、测试

@Test
void addDept(){
    Dept dept=new Dept();
    dept.setId(null);
    dept.setPname("后勤部");
    dept.setPremark("456");
    boolean b = dept.insert();
    System.out.println(b);
}
@Test
void pageDept(){
    Dept dept=new Dept();
    IPage<Dept> page=new Page<>(1,5);
    dept.selectPage(page,null);
    long total = page.getTotal();
    System.out.println("总数："+total);
}

五、条件构造器

@Test
void wrapperTest(){
    QueryWrapper<Dept> wrapper = new QueryWrapper<>();
    //or关系，不加or默认是and关系
    wrapper.eq(true,"id",1).or().eq("id",2);
    //and关系
    wrapper.between(true,"id",127,130);
    //小于关系
    wrapper.lt("id",128);
    //小于等于关系
    wrapper.le("id","128");
    //大于关系
    wrapper.gt("id",128);
    //大于等于关系
    wrapper.ge("id",128);
    //排序
    wrapper.orderByAsc("id");
    System.out.println(wrapper.getSqlSegment());
}

六、代码生成器

1、添加依赖（其他不变）

<dependencies>
    <dependency>
        <groupId>com.baomidougroupId>
        <artifactId>mybatis-plus-generatorartifactId>
        <version>3.2.0version>
    dependency>
    <dependency>
        <groupId>org.apache.velocitygroupId>
        <artifactId>velocity-engine-coreartifactId>
        <version>2.1version>
    dependency>
    <dependency>
        <groupId>org.freemarkergroupId>
        <artifactId>freemarkerartifactId>
        <version>2.3.29version>
    dependency>
    <dependency>
        <groupId>com.ibeetlgroupId>
        <artifactId>beetlartifactId>
        <version>3.0.16.RELEASEversion>
    dependency>
    
    <dependency>
        <groupId>mysqlgroupId>
        <artifactId>mysql-connector-javaartifactId>
        <version>8.0.17version>
    dependency>
dependencies>

2、创建生成器类

import com.baomidou.mybatisplus.core.exceptions.MybatisPlusException;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.config.*;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;
import com.baomidou.mybatisplus.generator.engine.FreemarkerTemplateEngine;
import org.apache.commons.lang3.StringUtils;
import java.util.Scanner;
/**
 *MP代码生成器
 */
public class Codegenerator {
    /**
     * 

     * 读取控制台内容
     * 
     */
    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.setAuthor("itan");
        //当代码生成后是否打开代码所在的文件夹
        gc.setOpen(false);
        // gc.setSwagger2(true); 实体属性 Swagger2 注解
        mpg.setGlobalConfig(gc);
        //给service设置名字
        gc.setServiceName("%sService");

        // 数据源配置
        DataSourceConfig dsc = new DataSourceConfig();
        dsc.setUrl("jdbc:mysql://localhost:3306/ssm?useSSL=true&serverTimezone=UTC");
        dsc.setDriverName("com.mysql.cj.jdbc.Driver");
        dsc.setUsername("root");
        dsc.setPassword("123456");
        mpg.setDataSource(dsc);

        // 包配置
        PackageConfig pc = new PackageConfig();
        pc.setModuleName(scanner("模块名"));
        //设置父模块名
        pc.setParent("com.itan");
        mpg.setPackageInfo(pc);

        // 策略配置
        StrategyConfig strategy = new StrategyConfig();
        //设置字段和表名是否把下划线改成驼峰命名规则
        strategy.setNaming(NamingStrategy.underline_to_camel);
        strategy.setColumnNaming(NamingStrategy.underline_to_camel);
        //是否启用lombokl
        strategy.setEntityLombokModel(true);
        //是否生成RestController
        strategy.setRestControllerStyle(true);
        // 设置生成的控制器类继承的父类
//        strategy.setSuperControllerClass("com.itan");
        // 写于父类中的公共字段
//        strategy.setSuperEntityColumns("id");
        //要设置生成哪些表，如果不设置就是生成所有的表
        strategy.setInclude(scanner("表名，多个英文逗号分割").split(","));
        strategy.setControllerMappingHyphenStyle(true);
        strategy.setTablePrefix(pc.getModuleName() + "_");
        mpg.setStrategy(strategy);
        mpg.setTemplateEngine(new FreemarkerTemplateEngine());
        mpg.execute();
    }
}

示例：

@RequestMapping("getAll")
public DataGridView getAll(CustomerVo customerVo){
  //分页插件
  IPage<Customer> page = new Page<>(customerVo.getPage(),customerVo.getLimit());
  //条件构造
  QueryWrapper<Customer> wrapper=new QueryWrapper<>();
  wrapper.like(StringUtils.isNotBlank(customerVo.getCustomername()),"customername",customerVo.getCustomername());
  wrapper.like(StringUtils.isNotBlank(customerVo.getTelephone()),"telephone",customerVo.getTelephone());
  wrapper.like(StringUtils.isNotBlank(customerVo.getConnectionperson()),"connectionperson",customerVo.getConnectionperson());
  //执行
  this.customerService.page(page,wrapper);
  return new DataGridView(page.getTotal(),page.getRecords());
}