二、快速开始——Spring集成Mybatis-Plus

大家好，又见面了，我是你们的朋友全栈君。

由于MyBatis-Plus是在MyBatis的基础上只做增强不做改变，因此其与Spring的整合非常简单。只需把MyBatis的依赖换成MyBatis的依赖，再把sqlSessionFactory换成MyBatis-Plus的即可。下面让我们在Spring中快速集成Mybatis-Plus的具体操作：

1、准备测试表

-- 创建库
CREATE DATABASE mp;
-- 使用库
USE mp;
-- 创建表
CREATE TABLE tbl_employee(
id INT(11) PRIMARY KEY AUTO_INCREMENT,
last_name VARCHAR(50),
email VARCHAR(50),
gender CHAR(1),
age int
);
INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('Tom','tom@jianshu.com',1,22);
INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('Jerry','jerry@jianshu.com',0,25);
INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('Black','black@jianshu.com',1,30);
INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('White','white@jianshu.com',0,35);

在自己的数据库中执行上面的sql。

2、新建Maven项目

2.1、新建一个空的maven父项目

2.1.1、我们在Idea里新建一个Maven父项目，用来管理之后我们所有模块的代码。在Idea中选择File → New → Project

2.1.2、在弹出的页面中选择 maven 然后 Next

2.1.3、填写自己喜欢的 groupId 和 artifactId,我这里填的是com.demo.mybatis-plus和mybatis-plus-in-action，填写完之后然后Next

2.1.4、继续点击 Next，如果所填路径不存在，Idea会提示是否穿件一个文件，点击OK即可

2.1.5、项目创建完毕后删除src文件夹，就得到了我们想要的空的父工程，如下图所示

2.2、修改pom文件

核心依赖：

<!-- mybatis-plus -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus</artifactId>
    <version>${mybatis.plus.version}</version>
</dependency>
<!-- spring -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-orm</artifactId>
    <version>${spring.version}</version>
</dependency>

完整依赖：

<!-- 统一管理项目依赖版本 -->
<properties>
    <mybatis.plus.version>3.2.0</mybatis.plus.version>
    <junit.version>4.12</junit.version>
    <log4j.version>1.2.17</log4j.version>
    <druid.version>1.1.20</druid.version>
    <mysql.version>5.1.48</mysql.version>
    <spring.version>5.2.0.RELEASE</spring.version>
    <lombok.version>1.18.10</lombok.version>
</properties>

<dependencies>
    <!-- mp 依赖
            mybatis-plus 会自动维护 mybatis 以及 mybatis-spring 相关的依赖
            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！
         -->
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus</artifactId>
        <version>${mybatis.plus.version}</version>
    </dependency>
    <!--junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
    </dependency>
    <!-- log4j -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>${log4j.version}</version>
    </dependency>
    <!-- druid -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>${druid.version}</version>
    </dependency>
    <!-- mysql -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql.version}</version>
    </dependency>
    <!-- spring -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <!--lombok -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>${lombok.version}</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

<!-- 设置JDK编译版本 -->
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
    </plugins>
</build>

2.3、新建mp01模块–快速开始

2.3.1、我们在Idea里新建一个mp01模块，在Idea中选中当前项目 → New → Module ；填写artifactId，点击 Next；确定 Module name的名称，点击 Finish 完成

2.3.2、新建完成后的项目如下

2.3.3、添加实体类

在 mp01\src\main\java\com\mp\beans\Employee.java 路径下添加实体类 Employee.java:

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

2.3.4、修改mp01的pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>mybatis-plus-in-action</artifactId>
        <groupId>com.demo.mybatis-plus</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>mp01</artifactId>

    <dependencies>
        <!-- mp 依赖
            mybatis-plus 会自动维护mybatis 以及 mybatis-spring相关的依赖
            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！
         -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>${mybatis.plus.version}</version>
        </dependency>
        <!--junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
        </dependency>
        <!-- log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <!-- druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>${druid.version}</version>
        </dependency>
        <!-- mysql -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <!-- spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <!--lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</project>

注意：这里在mp01的pom.xml文件中不添加上述依赖之后项目也是能正常运行的，但是我们加上相关依赖，是为让项目的依赖更加清晰一些

2.3.5、在 mp01\src\main\resources 中添加配置文件：

Spring 配置文件——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.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" 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
        mybatis提供的：org.mybatis.spring.SqlSessionFactoryBean
        mybatis-plus提供的：com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean
     -->
    <bean id="sqlSessionFactoryBean"
          class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
        <!-- 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.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.mp.mapper"></property>
    </bean>
</beans>

JDBC配置文件—— db.properties:

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mp?useUnicode=true&characterEncoding=UTF-8&useSSL=false
jdbc.username=root
jdbc.password=123456

日志文件——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>

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>

注意：mybatis-plus与spring整合，所有mybatis-plus的大部分都写在spring的配置文件中，这里定义一个空的mybatis-config.xml即可

2.3.6、测试

在 mp01\src\test\java\com\mp\test\TestMp.java 路径下添加测试类 TestMp.java:

public class TestMp {
    private ApplicationContext iocContext = new
            ClassPathXmlApplicationContext("applicationContext.xml");

    @Test
    public void testEnvironment() throws Exception {
        DataSource ds = iocContext.getBean("dataSource", DataSource.class);
        Connection conn = ds.getConnection();
        System.out.println(conn);
    }
}

运行 testEnvironment方法后如果能看到 Connection 就证明我们的配置可以了。