mybatis框架——逆向工程

电玩女神 2022-05-18 07:40 152阅读 0赞

Mybatis提供来一个逆向工程工具，通过逆向工程，可以帮助程序员根据单表来生成po类、mapper映射文件、mapper接口。下载地址为：[https://github.com/mybatis/generator/releases/tag/mybatis-generator-1.3.2][https_github.com_mybatis_generator_releases_tag_mybatis-generator-1.3.2]

首先我们创建一个Generator.java：

public class Generator {
        public static void main(String[] args) throws Exception {
            List<String> warnings = new ArrayList<String>();
            boolean overwrite = true;
            File configFile = new File("config/generatorConfig.xml");//指定一个配置文件
            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);
        }
    }

其中的配置文件为（generatorConfig.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>
        <context id="testTables" targetRuntime="MyBatis3">
            <commentGenerator>
                
                <property name="suppressAllComments" value="true" />
            </commentGenerator>
            
            <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://localhost:3306/mybatis" userId="root"
                password="root">
            </jdbcConnection>
            
    
            
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false" />
            </javaTypeResolver>
    
            
            <javaModelGenerator targetPackage="com.itheima.ms.po"
                targetProject=".\src">
                
                <property name="enableSubPackages" value="false" />
                
                <property name="trimStrings" value="true" />
            </javaModelGenerator>
            
            <sqlMapGenerator targetPackage="com.itheima.ms.mapper"
                targetProject=".\src">
                
                <property name="enableSubPackages" value="false" />
            </sqlMapGenerator>
            
            <javaClientGenerator type="XMLMAPPER"
                targetPackage="com.itheima.ms.mapper" targetProject=".\src">
                
                <property name="enableSubPackages" value="false" />
            </javaClientGenerator>
            
            <table tableName="items"></table>
            <table tableName="orders"></table>
            <table tableName="orderdetail"></table>
            <table tableName="user"></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>
        <context id="testTables" targetRuntime="MyBatis3">
            <commentGenerator>
                
                <property name="suppressAllComments" value="true" />
            </commentGenerator>
            
            <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                connectionURL="jdbc:mysql://localhost:3306/mybatis" userId="root"
                password="root">
            </jdbcConnection>
            
    
            
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false" />
            </javaTypeResolver>
    
            
            <javaModelGenerator targetPackage="com.itheima.ms.po"
                targetProject=".\src">
                
                <property name="enableSubPackages" value="false" />
                
                <property name="trimStrings" value="true" />
            </javaModelGenerator>
            
            <sqlMapGenerator targetPackage="com.itheima.ms.mapper"
                targetProject=".\src">
                
                <property name="enableSubPackages" value="false" />
            </sqlMapGenerator>
            
            <javaClientGenerator type="XMLMAPPER"
                targetPackage="com.itheima.ms.mapper" targetProject=".\src">
                
                <property name="enableSubPackages" value="false" />
            </javaClientGenerator>
            
            <table tableName="items"></table>
            <table tableName="orders"></table>
            <table tableName="orderdetail"></table>
            <table tableName="user"></table>
        </context>
    </generatorConfiguration>

然后运行程序，即可生成相应文件。（可以新建一个项目，将生成的代码拷贝到原项目中）

然后测试使用逆向工程生成的代码：

public class ItemsMapperTest {
        private ApplicationContext ctx;
        @Before
        public void setUp() throws Exception {
            ctx = new ClassPathXmlApplicationContext(
                    "spring/applicationContext.xml");
        }
        @Test
        public void testSelectByExample() {
            ItemsMapper mapper = (ItemsMapper) ctx.getBean("itemsMapper");  
            ItemsExample example = new ItemsExample();
            Criteria criteria = example.createCriteria();
            criteria.andNameLike("%背包%");//注意
            List<Items> list = mapper.selectByExample(example );
            System.out.println(list);
        }
    }

注意：Mapper.xml文件已经存在时，如果进行重新生成则mapper.xml文件时，内容不被覆盖而是进行内容追加，结果导致mybatis解析失败。

解决方法：删除原来已经生成的mapper xml文件再进行生成。Mybatis自动生成的po及mapper.java文件不是内容而是直接覆盖没有此问题。

[https_github.com_mybatis_generator_releases_tag_mybatis-generator-1.3.2]: https://github.com/mybatis/generator/releases/tag/mybatis-generator-1.3.2