简介

概述

MyBatis-Plus (opens new window)（简称 MP）是一个 MyBatis (opens new window)的增强工具
官网:https://baomidou.com/

前置知识

Mybatis
Spring
Maven

作用

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**

环境搭建

maven的配置

pom.xml

<!-- mp 依赖 -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId>
<version>2.3</version>
</dependency>
<!--junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.9</version>
</dependency>
<!-- log4j -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<!-- c3p0 -->
<dependency>
<groupId>com.mchange</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.5.2</version>
</dependency>
<!-- mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.37</version>
</dependency>
<!-- spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.10.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>4.3.10.RELEASE</version>
</dependency>

注意: Mybatis 及 Mybatis-Spring 依赖请勿加入项目配置，以免引起版本冲突！！！ Mybatis-Plus 会自动帮你维护！

mybatis的配置

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration></configuration>

log4j的配置

log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
<param name="Encoding" value="UTF-8" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-5p %d{MM-dd 
HH:mm:ss,SSS} %m (%F:%L) \n" />
</layout>
</appender>
<logger name="java.sql">
<level value="debug" />
</logger>
<logger name="org.apache.ibatis">
<level value="info" />
</logger>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
</root>
</log4j:configuration>

数据源的连接配置

db.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mp
jdbc.username=root
jdbc.password=1234

spring 的配置

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mybatis-spring="http://mybatis.org/schema/mybatis-spring"
xsi:schemaLocation="http://mybatis.org/schema/mybatis-spring 
http://mybatis.org/schema/mybatis-spring-1.2.xsd
http://www.springframework.org/schema/beans 
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context 
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/tx 
http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
  <!-- 数据源 -->
  <context:property-placeholder location="classpath:db.properties"/>
  <bean id="dataSource"  class="com.mchange.v2.c3p0.ComboPooledDataSource">
    <property name="driverClass" value="${jdbc.driver}"></property>
    <property name="jdbcUrl" value="${jdbc.url}"></property>
    <property name="user" value="${jdbc.username}"></property>
    <property name="password" value="${jdbc.password}"></property>
  </bean>
  <!-- 事务管理器 -->
  <bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"></property>
  </bean>
  <!-- 基于注解的事务管理 -->
  <tx:annotation-driven  transaction-manager="dataSourceTransactionManager"/>
  <!-- 配置 SqlSessionFactoryBean -->
  <!-- 使用MybatisPlus只需将这里的class换为 class="com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean" 即可 -->
  <bean id="sqlSessionFactoryBean"  class="org.mybatis.spring.SqlSessionFactoryBean">
    <!-- 数据源 -->
    <property name="dataSource" ref="dataSource"></property>
    <property name="configLocation"  value="classpath:mybatis-config.xml"></property>
    <!-- 别名处理 -->
    <property name="typeAliasesPackage" value="com.atguigu.mp.beans"></property>
  </bean>
  <!-- 配置 mybatis 扫描 mapper 接口的路径 -->
  <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage"  value="com.doyens.mp.mapper"></property>
  </bean>
</beans>

使用

基础:
mysql

-- 创建库
CREATE DATABASE mp;
-- 使用库
USE mp;
-- 创建表
CREATE TABLE tab_employee(
`id` INT PRIMARY KEY AUTO_INCREMENT,
`last_name` VARCHAR(30),
`email` VARCHAR(30),
`gender` TINYINT,
 `age` TINYINT
);
INSERT INTO tab_employee(last_name,email,gender,age) VALUES('Tom','tom@163.com',1,22);
INSERT INTO tab_employee(last_name,email,gender,age) VALUES('Jerry','jerry@163.com',0,25);
INSERT INTO tab_employee(last_name,email,gender,age) 
VALUES('Black','black@163.com',1,30); INSERT INTO 

Employee.java

public class Employee {
    private Integer id ;
    private String lastName;
    private String email ;
    private Integer gender ;
    private Integer age ;
}

EmployeeService.java

public interface EmployeeService {
    Integer insert(Employee employee);

    Integer deleteById(Integer id);

    Integer updateById(Employee employee);

    Employee selectById(Integer id);

    List<Employee> selectList(Wrapper<Employee> employee);
}

EmployeeServiceImpl.java

@Service("employeeService")
public class EmployeeServiceImpl implements EmployeeService {
    @Autowired
    private EmployeeMapper employeeMapper;


    @Override
    public Integer insert(Employee employee) {
        return employeeMapper.insert(employee);
    }

    @Override
    public Integer deleteById(Integer id) {
        return employeeMapper.deleteById(id);
    }

    @Override
    public Integer updateById(Employee employee) {
        return employeeMapper.updateById(employee);
    }

    @Override
    public Employee selectById(Integer id) {
        return employeeMapper.selectById(id);
    }

    @Override
    public List<Employee> selectList(Wrapper<Employee> employee) {
        return null;
    }
}

需要xxxMapper 继承 BaseMapper, BaseMapper 中提供了通用的 CRUD 方法
T为对应的实体类
例:
mapper

public interface EmployeeMapper extends BaseMapper<Employee> {


}

BaseMapper

包:com.baomidou.mybatisplus.mapper.BaseMapper
类型:接口
作用:提供了一些通用的CRUD方法
T : 对应的实体类

插入操作

1. Integer insert(T entity);
2. @TableName
3. 全局的 MP 配置:
4. @TableField
5. 全局的 MP 配置:
6. @TableId
7. 全局的 MP 配置:
8. 支持主键自增的数据库插入数据获取主键值
   Mybatis: 需要通过 useGeneratedKeys 以及 keyProperty 来设置
   MP: 自动将主键值回写到实体类中
9. Integer insertAllColumn(T entity)
   ————————————————————————————
   —

更新操作

1. Integer updateById(@Param(“et”) T entity);
2. Integer updateAllColumnById(@Param(“et”) T entity)

删除操作

1. Integer deleteById(Serializable id);
2. Integer deleteByMap(@Param(“cm”) Map<String, Object> columnMap);
3. Integer deleteBatchIds(List<? extends Serializable> idList);

查询操作

1. T selectById(Serializable id);
2. T selectOne(@Param(“ew”) T entity);
3. List selectBatchIds(List<? extends Serializable> idList);
4. List selectByMap(@Param(“cm”) Map<String, Object> columnMap);
5. List selectPage(RowBounds rowBounds, @Param(“ew”) Wrapper wrapper);