什么是逆向工程？在学习的过程中会发现，需要我们写大量的sql语句此时mybaatis官方为我们提供逆向工程可以针对单表自动生成的mybatis执行所需要的代码 使用方法： MyBatis Generator (MBG) can be run in the following ways:
- From the command prompt with an XML configuration
- As an Ant task with an XML configuration
- As a Maven Plugin
- From another Java program with an XML configuration
- From another Java program with a Java based configuration
推荐使用红色的方法 jar包
官方文档在解压后的doc文件中点击index.html
简单的讲解一下：
MyBatis GeneratorXML Configuration File Reference
建立新的工程：导入需要加入的jar
在config文件下的gengeratorConfig.xml 基本上都是固定的格式，不需要懂，只许看看懂红色部分的注释，以及相关标签的意义。
<?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>
<context id="testTables" targetRuntime="MyBatis3">
<commentGenerator>
<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3307/shopping"
userId="root"
password="1234">
</jdbcConnection>
<!-- 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 -->
<javaTypeResolver>
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- targetProject:生成PO类的位置 -->
<javaModelGenerator targetPackage="com.MrChengs.po"
targetProject=".\src">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
<!-- 从数据库返回的值被清理前后的空格 -->
<property name="trimStrings" value="true" />
</javaModelGenerator> <!-- targetProject:mapper映射文件生成的位置 -->
<sqlMapGenerator targetPackage="com.MrChengs.mapper"
targetProject=".\src">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
</sqlMapGenerator><!-- targetPackage：mapper接口生成的位置 -->
<javaClientGenerator type="XMLMAPPER"
targetPackage="com.MrChengs.mapper"
targetProject=".\src">
<!-- enableSubPackages:是否让schema作为包的后缀 -->
<property name="enableSubPackages" value="false" />
</javaClientGenerator><!-- 指定数据库表 -->
<table tableName="items"></table>
<table tableName="orders"></table>
<table tableName="orderdetail"></table>
<table tableName="user"></table>
</context>
</generatorConfiguration>
test目录下GeneratorSqlmap.java
public class GeneratorSqlmap {
public void generator() throws Exception{
List<String> warnings = new ArrayList<String>();
boolean overwrite = true;
//指定 逆向工程配置文件
File configFile = new File("config/generatorConfig.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);
}
public static void main(String[] args) throws Exception {
try {
GeneratorSqlmap generatorSqlmap = new GeneratorSqlmap();
generatorSqlmap.generator();
} catch (Exception e) {
e.printStackTrace();
}
}
}
都是固定的格式，固体的可以参考官方的文档。然后运行在简单说明一下如下的注释首先是表其次是表中的字段
2018-10-25 16:04:22,837 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "items"
2018-10-25 16:04:22,848 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "shopping..items"
2018-10-25 16:04:22,849 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "name", data type 12, in table "shopping..items"
2018-10-25 16:04:22,849 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "price", data type 7, in table "shopping..items"
2018-10-25 16:04:22,849 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "detail", data type -1, in table "shopping..items"
2018-10-25 16:04:22,849 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "pic", data type 12, in table "shopping..items"
2018-10-25 16:04:22,849 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "createtime", data type 93, in table "shopping..items"
2018-10-25 16:04:22,855 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "orders"
2018-10-25 16:04:22,859 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "shopping..orders"
2018-10-25 16:04:22,859 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "user_id", data type 4, in table "shopping..orders"
2018-10-25 16:04:22,859 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "number", data type 12, in table "shopping..orders"
2018-10-25 16:04:22,859 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "createtime", data type 93, in table "shopping..orders"
2018-10-25 16:04:22,859 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "note", data type 12, in table "shopping..orders"
2018-10-25 16:04:22,864 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "orderdetail"
2018-10-25 16:04:22,868 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "shopping..orderdetail"
2018-10-25 16:04:22,868 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "orders_id", data type 4, in table "shopping..orderdetail"
2018-10-25 16:04:22,868 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "items_id", data type 4, in table "shopping..orderdetail"
2018-10-25 16:04:22,868 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "items_num", data type 4, in table "shopping..orderdetail"
2018-10-25 16:04:22,869 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Retrieving column information for table "user"
2018-10-25 16:04:22,874 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "id", data type 4, in table "shopping..user"
2018-10-25 16:04:22,874 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "username", data type 12, in table "shopping..user"
2018-10-25 16:04:22,874 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "birthday", data type 91, in table "shopping..user"
2018-10-25 16:04:22,874 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "sex", data type 1, in table "shopping..user"
2018-10-25 16:04:22,874 [main] DEBUG [org.mybatis.generator.internal.db.DatabaseIntrospector] - Found column "address", data type 12, in table "shopping..user"
刷新观察com.MrChengs.pocom.MrCehngs.mapper两个包里面的文件
此时的文件我们得到了，在使用的时候我们不要进行对原有的代码的修改。 返回上一个博文将进行简单的小案例测试：有不懂的可以参考：MyBatis整合Spring 
复制图中的文件到本工程中
新建测试类
public class test {
private ApplicationContext applicationContext; public ApplicationContext getApplication(){
applicationContext = new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
return applicationContext;
} //根据主键id进行查询
@Test
public void test() { ItemsMapper items = (ItemsMapper) getApplication().getBean("itemsMapper"); Items it = items.selectByPrimaryKey(1);
System.out.println(it.toString());
}
//自定义查询条件
@Test
public void test1() {
ItemsMapper itemsMapperems = (ItemsMapper) getApplication().getBean("itemsMapper"); ItemsExample itemsExample = new ItemsExample();
//通过criteria构造条件查询
ItemsExample.Criteria criteria = itemsExample.createCriteria();
criteria.andNameEqualTo("笔记本");
//可能返回多个记录
List<Items> items = itemsMapperems.selectByExample(itemsExample); System.out.println(items);
}
}
均可以测试成功！！ 对于其他的方法，在使用的时候，可以参考自动生成的源码进行测试，都是可以测试成功的！ 逆向工程的使用极大的方便我们进行开发，作为程序员不需要过多的关注这个，我们进行了解基本的使用和用法即可。其余的增删改除，可以进行测试，在不会使用的情况下，可以参考源码，源码是之前的前几章节的内容.
