mybatis-plus（3.4.1）的基本（crud）使用

1.1mybatis-plus简介

MyBatis-Plus(简称 MP),是一个 MyBatis 的增强工具包，只做增强不做改变. 为简化开发工作、提高生产率而生。我们的愿景是成为 Mybatis 最好的搭档，就像魂斗罗中的 1P、2P，基友搭配，效率翻倍。

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

1.2 ssmp整合

引入相关坐标（创建数据库）

 <!--版本锁定-->
  <properties>
    <spring.version>5.3.2</spring.version>
    <slf4j.version>1.7.30</slf4j.version>
    <log4j.version>1.2.17</log4j.version>
  </properties>


  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>1.8.13</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context-support</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-orm</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-beans</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <!--spring-springMVC-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <!--spring-mybatis-->
    <dependency>
      <groupId>com.baomidou</groupId>
      <artifactId>mybatis-plus</artifactId>
      <version>3.4.1</version>
    </dependency>
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.0.9</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.15</version>
    </dependency>

    <!--servlet-jsp-->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.3</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.0</version>
    </dependency>
    <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
    <!--log4j-->
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>${log4j.version}</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>${slf4j.version}</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>${slf4j.version}</version>
    </dependency>
    <dependency>
      <groupId>javax.annotation</groupId>
      <artifactId>jsr250-api</artifactId>
      <version>1.0</version>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.8</version>
    </dependency>
    <!--json的包mvc返回json数据-->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.11.1</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.11.1</version>
    </dependency>
  </dependencies>

创建实体类和spring配置文件

package com.veo.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

import java.io.Serializable;

/**
 * (User)实体类
 *
 * @author makejava
 * @since 2021-01-01 20:55:05
 */
//@TableName(value = "user")
public class User implements Serializable {
    
    
    private static final long serialVersionUID = 228195023307246450L;
    /**
     * @TableId:
     *  value: 指定表中的主键列的列名， 如果实体属性名与列名一致，可以省略不指定.
     * 	type: 指定主键策略.
     * 	   AUTO(0)
     *     NONE(1)
     *     INPUT(2)
     *     ASSIGN_ID(3)
     *     ASSIGN_UUID(4)
     *     如果进行了全局配置主键方式可以不配置此注解，（二选一）不配置报错
     */
//    @TableId(type = IdType.AUTO,value = "id")
    private Integer id;

    /**
     * @TableField:
     *      value:与表字段相对应
     *      exist:表示该属性在数据库中不存在，该属性不会插入数据库
     */
//    @TableField(value = "name",exist = false)
    private String name;

    private String gender;

    private Integer age;

    private String address;

    private String qq;

    private String email;


    public Integer getId() {
    
    
        return id;
    }

    public void setId(Integer id) {
    
    
        this.id = id;
    }

    public String getName() {
    
    
        return name;
    }

    public void setName(String name) {
    
    
        this.name = name;
    }

    public String getGender() {
    
    
        return gender;
    }

    public void setGender(String gender) {
    
    
        this.gender = gender;
    }

    public Integer getAge() {
    
    
        return age;
    }

    public void setAge(Integer age) {
    
    
        this.age = age;
    }

    public String getAddress() {
    
    
        return address;
    }

    public void setAddress(String address) {
    
    
        this.address = address;
    }

    public String getQq() {
    
    
        return qq;
    }

    public void setQq(String qq) {
    
    
        this.qq = qq;
    }

    public String getEmail() {
    
    
        return email;
    }

    public void setEmail(String email) {
    
    
        this.email = email;
    }

    @Override
    public String toString() {
    
    
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                ", qq='" + qq + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

<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/tx
       http://www.springframework.org/schema/tx/spring-tx.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">
    <!--配置spring的注解扫描-->
    <context:component-scan base-package="com.veo">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>
    <!--配置数据库文件的加载路径-->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!--配置数据库连接池-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

    <!--配置mybatis-plus的sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
        <!--将DataSource注入SqlSessionFactoryBean-->
        <property name="dataSource" ref="dataSource"/>
        <!--注入全局配置到SqlSessionFactoryBean-->
        <property name="globalConfig" ref="globalConfig"/>
    </bean>

    <bean id="globalConfig" class="com.baomidou.mybatisplus.core.config.GlobalConfig">
        <!--将dbConfig配置到全局配置器-->
        <property name="dbConfig" ref="dbConfig"/>
        <!--将mySqlInjector配置到全局配置器-->
        <property name="sqlInjector" ref="mySqlInjector"/>
    </bean>

    <!--将自定义批量插入方法注入ioc-->
    <bean id="mySqlInjector" class="com.veo.config.MySqlInjector"/>

    <!--配置与mybatis-plus数据库相关的配置信息-->
    <bean id="dbConfig" class="com.baomidou.mybatisplus.core.config.GlobalConfig$DbConfig">
        <!--配置主键为自动增长-->
        <property name="idType" value="AUTO"/>
        <!--配置表的前缀-->
       <!-- <property name="tablePrefix" value="tb_"/>-->
        <!--配置数据库的名称-->
        <property name="schema" value="ssm6"/>
        <!--是否使用驼峰转下划线命名,只对表名生效-->
        <property name="tableUnderline" value="true"/>
    </bean>

    <!--将接口注入IOC容器中为service提供依赖注入-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.veo.mapper"/>
    </bean>

    <!--配置事务-->
    <bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="
           http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd
           http://www.springframework.org/schema/mvc
           http://www.springframework.org/schema/mvc/spring-mvc.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context.xsd
           http://www.springframework.org/schema/aop
		http://www.springframework.org/schema/aop/spring-aop.xsd
           ">
    <!--配置注解扫描-->
    <context:component-scan base-package="com.veo.controller">
        <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>

    <!--配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--配置注解扫描-->
    <mvc:annotation-driven/>

    <!--配置静态资源不过滤-->
    <mvc:resources location="/css/" mapping="/css/**" />
    <mvc:resources location="/fonts/" mapping="/fonts/**" />
    <mvc:resources location="/js/" mapping="/js/**" />

    <!--配置aop的注解扫描-->
    <aop:aspectj-autoproxy proxy-target-class="true"/>

</beans>

创建mapper接口和配置sql注入配置

配置实体类mapper接口继承BaseMapper类以实现基本增删改方法

package com.veo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.veo.entity.User;

import java.util.List;

public interface UserMapper extends BaseMapper<User> {
    
    

    //定义批量插入的方法
    int insertBatchSomeColumn(List<User> entityList);

    //定义修改部分列的方法
    int alwaysUpdateSomeColumnById(User entity);

    int deleteByIdWithFill(User entity);
}

配置sql注入配置文件（扩展实体类的批量删除和修改部分例的扩展方法）：

package com.veo.config;

import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.injector.DefaultSqlInjector;
import com.baomidou.mybatisplus.extension.injector.methods.AlwaysUpdateSomeColumnById;
import com.baomidou.mybatisplus.extension.injector.methods.InsertBatchSomeColumn;
import com.baomidou.mybatisplus.extension.injector.methods.LogicDeleteByIdWithFill;

import java.util.List;

public class MySqlInjector extends DefaultSqlInjector {
    
    
    @Override
    public List<AbstractMethod> getMethodList(Class<?> mapperClass) {
    
    
        List<AbstractMethod> methods= super.getMethodList(mapperClass);
        //加入扩展的方法
        methods.add(new InsertBatchSomeColumn());
        methods.add(new AlwaysUpdateSomeColumnById());
        methods.add(new LogicDeleteByIdWithFill());
        return methods;
    }
}

5.测试mybatis-plus常用方法

package com.veo.mybatis;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.veo.entity.User;
import com.veo.mapper.UserMapper;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;

import javax.sql.DataSource;
import java.sql.SQLException;
import java.util.*;

@RunWith(SpringRunner.class)
@ContextConfiguration(locations = {
    
    "classpath:applicationContext.xml"})
public class SampleTest {
    
    

    @Autowired
    private DataSource dataSource;

    @Autowired
    private UserMapper userMapper;

    /**
     * 测试数据库连接池是否连接成功
     * @throws SQLException
     */
    @Test
    public void testDataSource() throws SQLException {
    
    
        System.out.println(dataSource.getConnection());
    }

    @Test
    public void testInsert(){
    
    
        User user=new User();
        user.setName("大王");
        user.setAge(25);
        user.setGender("男");
        user.setAddress("北京");
        user.setQq("123456");
        user.setEmail("[email protected]");
        //insert方法在插入时, 会根据实体类的每个属性进行非空判断，
        //只有非空的属性对应的字段才会出现到SQL语句中,为空默认插入null
        int result = userMapper.insert(user);
        System.out.println("result:"+result);
    }

    @Test
    public void testInsertBatch(){
    
    
        User user1=new User();
        user1.setName("小王");
        User user2=new User();
        user2.setName("中王");
        User user3=new User();
        user3.setName("大王");
        List<User> userList=new ArrayList<>();
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        //批量插入数据
        int i = userMapper.insertBatchSomeColumn(userList);
        System.out.println("insertBatch:"+i);
    }

    @Test
    public void testUpdateById(){
    
    
        User user=new User();
        user.setId(36);
        user.setName("小龙女");
        user.setAge(18);
        user.setGender("女");
        //根据id进行更新
        int update = userMapper.updateById(user);
        System.out.println("updateResult:"+update);
    }

    @Test
    public void testUpdateByCondition(){
    
    
        User user=new User();
        user.setName("小龙女");
        user.setGender("女");
        //条件更新数据(没有条件默认更新数据库中的所有数据)
        //UPDATE user SET name=?, gender=? WHERE (id = ? AND qq LIKE ?)
        QueryWrapper<User> wrapper=new QueryWrapper<User>();
        wrapper.eq("id","35");
        wrapper.like("qq","123");
        int update = userMapper.update(user, wrapper);
        System.out.println("updateResult:"+update);
    }


    @Test
    public void testDelete(){
    
    
        QueryWrapper<User> wrapper=new QueryWrapper<User>();
        User user=new User();
        user.setName("小龙女");
        user.setGender("女");
        wrapper.setEntity(user);
        //根据传入的user进行条件删除
        int i = userMapper.delete(wrapper);
        System.out.println("delete:"+i);

    }

    @Test
    public void testDeleteBatch(){
    
    
        //根据id进行批量删除
        int i = userMapper.deleteBatchIds(Arrays.asList("1","2","3"));
        System.out.println("delete:"+i);
    }

    @Test
    public void testDeleteById(){
    
    
        //根据id进行删除
        int i = userMapper.deleteById(1);
        System.out.println("delete:"+i);
    }

    @Test
    public void testDeleteByCondition(){
    
    
        //根据map条件进行删除(键名与数据库的字段名相同)
        Map<String,Object> map=new HashMap<String, Object>();
        map.put("name","小王");
        map.put("id","5");
        int i = userMapper.deleteByMap(map);
        System.out.println("delete:"+i);
    }

    /**
     * 查询所有数据（或条件查询数据）
     */
    @Test
    public void testSelectAll(){
    
    
        //无条件查询所有
        List<User> users = userMapper.selectList(null);
        users.forEach(System.out::println);
        //条件查询
        QueryWrapper<User> wrapper=new QueryWrapper<User>();
        wrapper.eq("gender","女");
        wrapper.like("name","张");
        wrapper.le("age",25);
        List<User> userList = userMapper.selectList(wrapper);
        userList.forEach(System.out::println);
    }

    @Test
    public void testSelectById(){
    
    
        User user=new User();
        user.setId(12);
        //根据id查询数据
        User user1 = userMapper.selectById(user);
        System.out.println(user1);
    }


    @Test
    public void testSelectOne(){
    
    
        //查询单一数据
        QueryWrapper<User> wrapper=new QueryWrapper<User>();
        wrapper.eq("id","11");
        User user = userMapper.selectOne(wrapper);
        System.out.println(user);
    }

    @Test
    public void testSelectPage(){
    
    
        //分页查询
        Page<User> page=new Page<User>(3,3);
        QueryWrapper<User> wrapper=new QueryWrapper<User>();
        wrapper.eq("gender","女");
        wrapper.orderByDesc("age");
        Page<User> userPage = userMapper.selectPage(page, wrapper);
        List<User> records = userPage.getRecords();
        records.forEach(System.out::println);
        System.out.println("总记录数："+userPage.getTotal());
        System.out.println("每页的数量："+userPage.getSize());
        System.out.println("共几页："+userPage.getPages());
        System.out.println("当前："+userPage.getCurrent());
    }
}

整合要点

坐标导入无需导入spring和mybatis和整合坐标，以及mybatis的坐标，只需导入mybatis-plus的坐标（mybatis-plus中整合了mybatis和spring的jar包）
spring的配置文件中注入的sqlSessionFactoryBean换成com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean
定义实体类mapper接口实现BaseMapper类，自定义和扩展的配置类要注入IOC容器后再注入到com.baomidou.mybatisplus.core.config.GlobalConfig的全局配置类中，在注入到com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBeanmybatis-plus的sqlSessionFactoryBean中，这样自定义的配置文件才会生效
要进行基本增删改要定义id的主键生成类型(二选一)

注解方式：

@TableName(value = "user")
public class User implements Serializable {
    
    
    private static final long serialVersionUID = 228195023307246450L;
    /**
     * @TableId:
     *  value: 指定表中的主键列的列名， 如果实体属性名与列名一致，可以省略不指定.
     * 	type: 指定主键策略.
     * 	   AUTO(0)
     *     NONE(1)
     *     INPUT(2)
     *     ASSIGN_ID(3)
     *     ASSIGN_UUID(4)
     *     如果进行了全局配置主键方式可以不配置此注解，（二选一）不配置报错
     */
    @TableId(type = IdType.AUTO,value = "id")
    private Integer id;

    /**
     * @TableField:
     *      value:与表字段相对应
     *      exist:表示该属性在数据库中不存在，该属性不会插入数据库
     */
    @TableField(value = "name",exist = false)
    private String name;

全局配置方式：

    <!--配置mybatis-plus的sqlSessionFactory-->
    <bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
        <!--将DataSource注入SqlSessionFactoryBean-->
        <property name="dataSource" ref="dataSource"/>
        <!--注入全局配置到SqlSessionFactoryBean-->
        <property name="globalConfig" ref="globalConfig"/>
    </bean>

    <bean id="globalConfig" class="com.baomidou.mybatisplus.core.config.GlobalConfig">
        <!--将dbConfig配置到全局配置器-->
        <property name="dbConfig" ref="dbConfig"/>
        <!--将mySqlInjector配置到全局配置器-->
        <property name="sqlInjector" ref="mySqlInjector"/>
    </bean>

    <!--将自定义批量插入方法注入ioc-->
    <bean id="mySqlInjector" class="com.veo.config.MySqlInjector"/>

5.要将创建的实体类mapper接口注入spring的IOC容器，否则会注入不成功

 <!--将接口注入IOC容器中为service提供依赖注入-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.veo.mapper"/>
    </bean>

mybatis-plus（3.4.1）的基本（crud）使用

1.1mybatis-plus简介

1.2 ssmp整合

整合要点

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