正向工程：先创建java实体类，由框架负责根据实体类生成数据库表。Hibernate是支持正向工程的

逆向工程：先创建数据库表，由框架根据数据库表，反向生成如下资源：
Java实体类
Mapper接口
Mapper映射文件

1. 逆向工程的创建步骤（简洁版）

1、在pom.xml中添加依赖和插件

<packaging>jarpackaging>

    
    <dependencies>
        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.7version>
        dependency>
        
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
            <scope>testscope>
        dependency>
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.3version>
        dependency>
        
        <dependency>
            <groupId>log4jgroupId>
            <artifactId>log4jartifactId>
            <version>1.2.17version>
        dependency>
    dependencies>
    
    <build>
        
        <plugins>
            
            <plugin>
                <groupId>org.mybatis.generatorgroupId>
                <artifactId>mybatis-generator-maven-pluginartifactId>
                <version>1.3.0version>
                
                <dependencies>
                    
                    <dependency>
                        <groupId>org.mybatis.generatorgroupId>
                        <artifactId>mybatis-generator-coreartifactId>
                        <version>1.3.2version>
                    dependency>
                    
                    <dependency>
                        <groupId>com.mchangegroupId>
                        <artifactId>c3p0artifactId>
                        <version>0.9.2version>
                    dependency>
                    
                    <dependency>
                        <groupId>mysqlgroupId>
                        <artifactId>mysql-connector-javaartifactId>
                        <version>5.1.8version>
                    dependency>
                dependencies>
            plugin>
        plugins>
    build>
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2、创建mybatis的核心配置文件mybatis-config.xml

<configuration>
    

    
    <properties resource="jdbc.properties"/>

    
    <typeAliases>
        
        
        <package name="类型别名所在的包"/>
    typeAliases>

    
    <environments default="development">
        
        <environment id="development">
            
            <transactionManager type="JDBC"/>
            
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            dataSource>
        environment>
    environments>
    
    <mappers>
        
        <package name="映射文件所在的包"/>
        
    mappers>
configuration>
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3、创建逆向工程配置文件
文件名必须是：generatorConfig.xml

DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
        <generatorConfiguration>
        
            <context id="DB2Tables" targetRuntime="MyBatis3Simple">
            
                <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                                connectionURL="jdbc:mysql://localhost:3306/mybatis"
                                userId="root"
                                password="123456">
                jdbcConnection>
                
                <javaModelGenerator targetPackage="com.atguigu.mybatis.bean" 
                                    targetProject=".\src\main\java">
                    <property name="enableSubPackages" value="true" />
                    <property name="trimStrings" value="true" />
                javaModelGenerator>
                
                <sqlMapGenerator targetPackage="com.atguigu.mybatis.mapper"
                                 targetProject=".\src\main\resources">
                    <property name="enableSubPackages" value="true" />
                sqlMapGenerator>
                
                <javaClientGenerator type="XMLMAPPER"
                                     targetPackage="com.atguigu.mybatis.mapper" 
                                     targetProject=".\src\main\java">
                    <property name="enableSubPackages" value="true" />
                javaClientGenerator>
                
                
                
                <table tableName="t_emp" domainObjectName="Emp"/>
                <table tableName="t_dept" domainObjectName="Dept"/>
            context>
        generatorConfiguration>
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4、执行MBG插件的generate目标

执行之后，逆向工程就会根据表的信息自动生成表所对应的mapper接口、实体类以及映射文件。

1. 逆向工程（豪华至尊版版）

在generatorConfig.xml配置文件中将targetRuntime属性换为MyBatis3即可。