1、Mybatis 逆向工程是什麼？

MyBatis Generator

簡稱mbg,是一個專門為Mybatis框架使用者定製的程式碼生成器，可以快速的根據表生成對應的

對映檔案、介面和bean類。支援基本的增刪改查，以及QBC（Query By Criteria）風格的條件查詢。

2、如何使用

首先說一下，以下配置必須放在一個完整的mybatis專案下，別犯傻哈！

(即引入了mybatis相關的jar包和 具備mybatis全域性配置檔案）

1）匯入mybatis逆向工程相應的jar包

2）編寫全域性配置檔案mbg.xml

<?xml version="1.0" encoding="UTF-8"
 
?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>

    <!--
        targetRuntime="MyBatis3Simple":生成簡單版的CRUD
        MyBatis3:豪華版

     -->
 

    <context id="DB2Tables" targetRuntime="MyBatis3">
        <!-- jdbcConnection：指定如何連線到目標資料庫 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/mybatis?allowMultiQueries=true"
                        userId
 
="root"
                        password="houchen">
        </jdbcConnection>

        <!--  -->
        <javaTypeResolver >
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- javaModelGenerator：指定javaBean的生成策略
        targetPackage="test.model"：目標包名
        targetProject="\MBGTestProject\src"：目標工程
        -->
        <javaModelGenerator targetPackage="com.atguigu.mybatis.bean"
                            targetProject=".\src">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!-- sqlMapGenerator：sql對映生成策略： -->
        <sqlMapGenerator targetPackage="com.atguigu.mybatis.dao"
                         targetProject=".\conf">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>

        <!-- javaClientGenerator:指定mapper介面所在的位置 -->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.atguigu.mybatis.dao"
                             targetProject=".\src">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

        <!-- 指定要逆向分析哪些表：根據表要建立javaBean -->
        <table tableName="tbl_dept" domainObjectName="Department"></table>
        <table tableName="tbl_employee" domainObjectName="Employee"></table>
    </context>
</generatorConfiguration>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>

    <!--
        targetRuntime="MyBatis3Simple":生成簡單版的CRUD
        MyBatis3:豪華版

     -->
    <context id="DB2Tables" targetRuntime="MyBatis3">
        <!-- jdbcConnection：指定如何連線到目標資料庫 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/mybatis?allowMultiQueries=true"
                        userId="root"
                        password="houchen">
        </jdbcConnection>

        <!--  -->
        <javaTypeResolver >
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- javaModelGenerator：指定javaBean的生成策略
        targetPackage="test.model"：目標包名
        targetProject="\MBGTestProject\src"：目標工程
        -->
        <javaModelGenerator targetPackage="com.atguigu.mybatis.bean"
                            targetProject=".\src">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!-- sqlMapGenerator：sql對映生成策略： -->
        <sqlMapGenerator targetPackage="com.atguigu.mybatis.dao"
                         targetProject=".\conf">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>

        <!-- javaClientGenerator:指定mapper介面所在的位置 -->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.atguigu.mybatis.dao"
                             targetProject=".\src">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

        <!-- 指定要逆向分析哪些表：根據表要建立javaBean -->
        <table tableName="tbl_dept" domainObjectName="Department"></table>
        <table tableName="tbl_employee" domainObjectName="Employee"></table>
    </context>
</generatorConfiguration>

3) 測試逆向工程

@Test
public void testMybatisGenerate() throws Exception {
    List<String> warnings = new ArrayList<String>();
    boolean overwrite = true;
    File configFile = new File("mbg.xml");
    ConfigurationParser cp = new ConfigurationParser(warnings);
    Configuration config = cp.parseConfiguration(configFile);
    DefaultShellCallback callback = new DefaultShellCallback(overwrite);
    MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config,
            callback, warnings);
    myBatisGenerator.generate(null);
}

確實生成了相應的實體、介面和 mapper: