【MyBatis学习15】MyBatis的逆向工程生成代码

最新推荐文章于 2025-05-28 09:58:31 发布

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本文介绍MyBatis逆向工程的使用方法，包括配置文件设置、代码生成过程及生成代码的测试。通过逆向工程，程序员可以快速生成单表对应的Mapper.xml、Mapper.java和POJO类。

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1. 什么是逆向工程

　　mybatis的一个主要的特点就是需要程序员自己编写sql，那么如果表太多的话，难免会很麻烦，所以mybatis官方提供了一个逆向工程，可以针对单表自动生成mybatis执行所需要的代码（包括mapper.xml、mapper.java、po..）。一般在开发中，常用的逆向工程方式是通过数据库的表生成代码。

2. 使用逆向工程

　　使用mybatis的逆向工程，需要导入逆向工程的jar包，我用的是mybatis-generator-core-1.3.2，已经上传到下载频道了（点我下载），下面开始总结一下mybatis逆向工程的使用步骤。

2.1 新建一个工程（重要）

　　我们要新建一个java工程，这个工程专门用来使用逆向工程生成代码的。有些人可能会问，为什么要新建一个工程呢？直接在原来工程中你想生成不就可以了么？确实是这样，可以在原来的工程中生成，但是有风险，因为mybatis是根据配置文件来生成的（下面会说到），如果生成的路径中有相同的文件，那么就会覆盖原来的文件，这样会有风险。所以开发中一般都会新建一个java工程来生成，然后将生成的文件拷贝到自己的工程中，这也不麻烦，而且很安全。如下：
逆向工程
　　从上图中看，1就是要执行的java代码，执行它即可生成我们需要的代码；2是执行过程中新建的包，这个包都可以在4的配置文件中指定，最好是跟我们自己项目的包名一致，后面就可以直接拷贝了，就不需要修改包名了；3就是jar包咯；4是配置文件。下面会详细分析。

2.1 生成代码的配置文件

　　mybatis逆向工程生成代码需要一个配置文件，名字随便起。然后mybatis会根据这个配置文件中的配置，生成相应的代码。下载好了jar包后，里面有帮助文档，打开后里面有配置文件的模板，这里就不再赘述了，下面先把配置文件写好：

<code class="language-xml hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-pi" style="color: rgb(0, 102, 102); box-sizing: border-box;"><?xml version="1.0" encoding="UTF-8"?></span>
<span class="hljs-doctype" style="color: rgb(102, 0, 102); box-sizing: border-box;"><!DOCTYPE generatorConfiguration
  PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd"></span>

<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">generatorConfiguration</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">context</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"testTables"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetRuntime</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"MyBatis3"</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">commentGenerator</span>></span>
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- 是否去除自动生成的注释 true：是 ： false:否 --></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">property</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"suppressAllComments"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">value</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"true"</span> /></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">commentGenerator</span>></span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!--数据库连接的信息：驱动类、连接地址、用户名、密码 --></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">jdbcConnection</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">driverClass</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"com.mysql.jdbc.Driver"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">connectionURL</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"jdbc:mysql://localhost:3306/mybatis"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">userId</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"root"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">password</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"root"</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">jdbcConnection</span>></span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- <jdbcConnection driverClass="oracle.jdbc.OracleDriver"
            connectionURL="jdbc:oracle:thin:@127.0.0.1:1521:yycg" 
            userId="yycg"
            password="yycg">
        </jdbcConnection> --></span>

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL和NUMERIC类型解析为java.math.BigDecimal --></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">javaTypeResolver</span>></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">property</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"forceBigDecimals"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">value</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"false"</span> /></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">javaTypeResolver</span>></span>

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- targetProject:生成PO类的位置，重要！！ --></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">javaModelGenerator</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetPackage</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"mybatis.po"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetProject</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">".\src"</span>></span>
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- enableSubPackages:是否让schema作为包的后缀 --></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">property</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"enableSubPackages"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">value</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"false"</span> /></span>
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- 从数据库返回的值被清理前后的空格 --></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">property</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"trimStrings"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">value</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"true"</span> /></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">javaModelGenerator</span>></span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- targetProject:mapper映射文件生成的位置，重要！！ --></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">sqlMapGenerator</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetPackage</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"mybatis.mapper"</span> 
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetProject</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">".\src"</span>></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">property</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"enableSubPackages"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">value</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"false"</span> /></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">sqlMapGenerator</span>></span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- targetPackage：mapper接口生成的位置，重要！！ --></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">javaClientGenerator</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">type</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"XMLMAPPER"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetPackage</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"mybatis.mapper"</span> 
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">targetProject</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">".\src"</span>></span>
            <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">property</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"enableSubPackages"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">value</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"false"</span> /></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">javaClientGenerator</span>></span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;"><!-- 指定数据库表，要生成哪些表，就写哪些表，要和数据库中对应，不能写错！ --></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">tableName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"items"</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">tableName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"orders"</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">tableName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"orderdetail"</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">tableName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"user"</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">table</span>></span>        
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">context</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">generatorConfiguration</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li></ul>

　　从上面的配置文件中可以看出，配置文件主要要做的几件事是：

连接数据库，这是必须的，要不然怎么根据数据库的表生成代码呢？
指定要生成代码的位置，要生成的代码包括po类， mapper.xml和mapper.java
指定数据库中想要生成哪些表

2.3 执行生成程序

　　配置文件搞好了，然后就执行以下生成程序即可生成了，生成的java程序，下载的逆向工程文档中都有示例，如下：

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">GeneratorSqlmap</span> {</span>

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">generator</span>() <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> Exception{

        List<String> warnings = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ArrayList<String>();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> overwrite = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//指向逆向工程配置文件</span>
        File configFile = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"generatorConfig.xml"</span>); 
        ConfigurationParser cp = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(configFile);
        DefaultShellCallback callback = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> MyBatisGenerator(config,
                callback, warnings);
        myBatisGenerator.generate(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);

    } 
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">main</span>(String[] args) <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> Exception {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
            GeneratorSqlmap generatorSqlmap = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> GeneratorSqlmap();
            generatorSqlmap.generator();
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e) {
            e.printStackTrace();
        }

    }

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li></ul>

　　运行一下即可，运行完了后刷新一下工程，就可以看到最新生成的代码了。

　　这里可以看出有个细节，每个po类多了一个东西，就是xxxExample.java，这个类是给用户自定义sql是用的，后面我会提到。到这里就生成好了，下面我们就把生成的代码拷贝到自己的工程使用了，为了简便，这里我就拷贝ItemsMapper.java/ItemsMapper.xml/Items.java/ItemsExample.java这一类的，其他都一样。

3. 测试生成的代码

　　我们针对ItemsMapper.java新建一个测试类，测试其中的几个方法：

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ItemsMapperTest</span> {</span>

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> SqlSessionFactory sqlSessionFactory;

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Before</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">setUp</span>() <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">throws</span> Exception {
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 创建sqlSessionFactory</span>
        String resource = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SqlMapConfig.xml"</span>; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// mybatis配置文件</span>

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 得到配置文件的流</span>
        InputStream inputStream = Resources.getResourceAsStream(resource);

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 创建会话工厂SqlSessionFactory,要传入mybaits的配置文件的流</span>
        sqlSessionFactory = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> SqlSessionFactoryBuilder().build(inputStream);

    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//普通的插入，跟我们之前的插入是一样的</span>
    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Test</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">testInsert</span>() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        ItemsMapper itemsMapper = sqlSession.getMapper(ItemsMapper.class);

        Items items = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Items();
        items.setName(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"手机"</span>);
        items.setPrice(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>f);
        items.setCreatetime(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Date());
        itemsMapper.insert(items);
        sqlSession.commit();
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//还有一个insertSelective(items);方法，是插入的项不为空时，才将那个字段拼接到sql中</span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//可以下自动生成的xml文件就知道了。</span>
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//自定义查询</span>
    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Test</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">testSelectByExample</span>() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        ItemsMapper itemsMapper = sqlSession.getMapper(ItemsMapper.class);

        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//自定义查询，这就用到了ItemsExample类了，里面有个Criteria内部类，专门用来封装自定义查询条件的</span>
        ItemsExample itemsExample = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ItemsExample();
        ItemsExample.Criteria criteria = itemsExample.createCriteria();
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//andNameEqualTo相当于在sql中拼接一个“AND name='背包'”</span>
        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//还有其他很多方法，都是用来自定义查询条件的，可以自己看一下不同的方法</span>
        criteria.andNameEqualTo(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"背包"</span>);
        List<Items> itemsList = itemsMapper.selectByExample(itemsExample);
        System.out.println(itemsList);
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//根据主键查询，跟原来一样</span>
    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Test</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">testSelectByPrimaryKey</span>() {
        ItemsMapper itemsMapper = sqlSessionFactory.openSession().getMapper(ItemsMapper.class);
        Items items = itemsMapper.selectByPrimaryKey(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);
        System.out.println(items);
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//根据主键更新item，跟原来一样</span>
    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Test</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">testUpdateByPrimaryKey</span>() {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        ItemsMapper itemsMapper = sqlSession.getMapper(ItemsMapper.class);
        Items items = itemsMapper.selectByPrimaryKey(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);
        items.setPrice(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3540</span>f);
        itemsMapper.updateByPrimaryKey(items);
        sqlSession.commit();
    }
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li></ul>

　　可以看出，逆向工程生成的代码，基本上和之前使用的差不多，只不过它更规范一点，而且还多了自定义查询条件的java类，用起来还是挺方便的。关于mybatis的逆向工程就总结到这吧。
　　

　　相关阅读：http://blog.youkuaiyun.com/column/details/smybatis.html
　　学习笔记源码下载地址：https://github.com/eson15/MyBatis_Study

—–乐于分享，共同进步！
—–我的博客主页：http://blog.youkuaiyun.com/eson_15