Mybatis 二（3）之逆向工程

墨蓝 2022-04-18 05:46 177阅读 0赞

### **1. 逆向工程生成代码：** ###

**【参考文档（配置全局文档、测试代码）网址： [http://www.mybatis.org/generator/configreference/xmlconfig.html][http_www.mybatis.org_generator_configreference_xmlconfig.html] 】**  
在企业中，设计阶段会进行表设计，创建逆向工程，由数据表——》Java代码；  
需要：mapper.xml、mapper.java、POJO表名（表名.java）；  
**配置：**

1.  所需 .jar包，数据库驱动包
2.  需要配置的地方：（根据 generatorConfig.xml （名字任意）文件的内容进行配置）  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDI5OTIz_size_16_color_FFFFFF_t_70]  
    **generatorConfig.xml（原）**

<?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>    
    	    
        <classPathEntry  location="mysql-connector-java-5.1.31.jar"/>    
        <context id="DB2Tables"  targetRuntime="MyBatis3">    
            <commentGenerator>    
                <property name="suppressDate" value="true"/>    
                    
                <property name="suppressAllComments" value="true"/>    
            </commentGenerator>    
                
            <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://127.0.0.1/edu" userId="root" password="root">  
            </jdbcConnection>    
            <javaTypeResolver>    
                <property name="forceBigDecimals" value="false"/>    
            </javaTypeResolver>    
                
            <javaModelGenerator targetPackage="com.domain" targetProject="src">    
                <property name="enableSubPackages" value="true"/>    
                <property name="trimStrings" value="true"/>    
            </javaModelGenerator>    
                
            <sqlMapGenerator targetPackage="com.mapping" targetProject="src">    
                <property name="enableSubPackages" value="true"/>    
            </sqlMapGenerator>    
                
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.dao" targetProject="src">    
                <property name="enableSubPackages" value="true"/>    
            </javaClientGenerator>    
                
            <table tableName="User" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>  
        </context>    
    </generatorConfiguration>

**generatorConfig.xml（改后）**

<?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="DB2Tables"  targetRuntime="MyBatis3">    
            <commentGenerator>    
                <property name="suppressDate" value="true"/>    
                    
                <property name="suppressAllComments" value="true"/>    
            </commentGenerator>    
                
            <jdbcConnection driverClass="com.mysql.jdbc.Driver" 
    	    connectionURL="jdbc:mysql://localhost:3306/test"
    	    userId="root"
    	    password="12345">  
            </jdbcConnection>    
            <javaTypeResolver>    
                <property name="forceBigDecimals" value="false"/>    
            </javaTypeResolver>    
            
                
            <javaModelGenerator targetPackage="com.mdd.po" targetProject=".\src">    
    	     <property name="enableSubPackages" value="false"/> //是否让schema作为包的后缀   
    	     <property name="trimStrings" value="true"/> //从数据库打字时输入的前后空格是否被清空   
            </javaModelGenerator>   
            
                
            <sqlMapGenerator targetPackage="com.mdd.mapper" targetProject=".\src">    
    	     <property name="enableSubPackages" value="false"/>    
            </sqlMapGenerator>    
            
                
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.mdd.mapper" targetProject=".\src">    
    	     <property name="enableSubPackages" value="false"/>    
           </javaClientGenerator>  
            
                
            <table tableName="users"/>
            
        </context>    
    </generatorConfiguration>

**1.数据库连接**

**2.配置POJO类的包路径**

<javaModelGenerator targetPackage="com.mdd.po" targetProject=".\src">    
         <property name="enableSubPackages" value="false"/> //是否让schema作为包的后缀   
         <property name="trimStrings" value="true"/> //从数据库打字时输入的前后空格是否被清空   
    </javaModelGenerator>

**3.配置 mapper.xml 包路径**

**4.配置 mapper.java 接口生成的位置**

**5.指定数据表**

**Test.java**  
（测试代码网址: [http://www.mybatis.org/generator/running/runningWithJava.html][http_www.mybatis.org_generator_running_runningWithJava.html] ）  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDI5OTIz_size_16_color_FFFFFF_t_70 1]

public class Test{
       public void generator()throws Exception{
    	List<String> warnings = new ArrayList<String>();
    	boolean overwrite = true;
    	File configFile = new File("generatorConfig.xml");//此处是自定义任意名称的全局配置文件名
    	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){
    	try{
    	    Test t=new Test();
    	t.generator();
    	}catch(Exception e){
    	    e.printStackTrace();
    	}		
      }
      
    }

**运行结果：**

运行后生成了 com.mdd.mapper、com.mdd.po两个包。

### **2. 使用：** ###

1.  配置全局配置文件 xml
2.  运行 java
3.  使用：将所产生的 Java代码拷贝到项目中，再创建 UserMapperTest.java 测试类（创建时点击 下一步（不是finish）来选择生成的方法：）  
    **使用自定义方法时，先根据已有的 XxExample类生成对应的 xxExample对象，再调用xxExample.createCriteria()方法生成criteria，再调用 criteria对象的对应的各种方法**

public class AppTest {
        SqlSessionFactory sqlSessionFactory=null;
        @Before
        public void init() throws IOException {
            InputStream inputStream=Resources.getResourcesAsStream("SqlMapConfig.xml");
            sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        }
        /*自定义方法条件（不用选择的生成的，下面的都是创建测试类时自己选择后生成的方法）*/
        @Test
        public  void testSelectByPrimaryKey(){
            SqlSession sqlSession=sqlSessionFactory.openSession();
            UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
            UserExample example=new UserExample();
            UserExample.Criteria criteria=example.createCriteria();
            criteria.andUsernameEqualTo("Tom");
            List<User> userList=userMapper.selectByExample(example);
            sqlSession1.close();
            for (User user:userList) {
            	System.out.println(user1.getId()+","+user1.getUsername());
            }
        }
        /*查*/
        @Test
        public  void testSelectByPrimaryKey(){
            SqlSession sqlSession=sqlSessionFactory.openSession();
            UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
            User user=userMapper.selectByPrimaryKey(1);
            sqlSession1.close();
            System.out.println(user1.getId()+","+user1.getUsername());
        }
        //增
        @Test
        public  void testInsert(){
            SqlSession sqlSession=sqlSessionFactory.openSession();
            UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
            User user=new User();
            user.setUsername("逆向工程");
            userMapper.insert(user);
            sqlSession1.commit();
            sqlSession1.close();
        }
        //删
        @Test
        public  void testDeleteByPrimaryKey(){
            SqlSession sqlSession=sqlSessionFactory.openSession();
            UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
            userMapper.deleteByPrimaryKey(3);
            sqlSession1.commit();
            sqlSession1.close();
        }
        //改
        @Test
        public  void testUpdateByPrimaryKey(){
            SqlSession sqlSession=sqlSessionFactory.openSession();
            UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
            User user=new User(1,"jay",20);
            userMapper.updateByPrimaryKey(user);
            sqlSession1.commit();
            sqlSession1.close();
        }
    }

[http_www.mybatis.org_generator_configreference_xmlconfig.html]: http://www.mybatis.org/generator/configreference/xmlconfig.html
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDI5OTIz_size_16_color_FFFFFF_t_70]: /images/20220418/f02e42a3ee10409b81d370591646f1e2.png
[http_www.mybatis.org_generator_running_runningWithJava.html]: http://www.mybatis.org/generator/running/runningWithJava.html
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMDI5OTIz_size_16_color_FFFFFF_t_70 1]: /images/20220418/7b22d7991489478aa795e5fff41169ab.png