Mybatis篇-（八）逆向工程(MBG)

àì夳堔傛蜴生んèń 2023-10-04 12:48 11阅读 0赞

## 八、Mybatis-逆向工程 ##

>  *  MyBatis Generator： 简称MBG，是一个专门为MyBatis框架使用者定 制的代码生成器，可以快速的根据表生成对应的 映射文件，接口，以及bean类。支持基本的增删 改查，以及QBC风格的条件查询。但是表连接、 存储过程等这些复杂sql的定义需要我们手工编写
>  *  [mbg下载地址][mbg]

**mbg的使用**

*  导入jar包  
    ![在这里插入图片描述][2021050816404355.png]
 *  配置文件的编写

<?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="suppressAllComments" value="false" />
            </commentGenerator>
            
            <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                            connectionURL="jdbc:mysql://localhost:3306/mybatis?allowMultiQueries=true"
                            userId="root"
                            password="lian0911">
            </jdbcConnection>
    
            
            <javaTypeResolver >
                <property name="forceBigDecimals" value="false" />
            </javaTypeResolver>
    
            
            <javaModelGenerator targetPackage="com.cvzhanshi.mybatis.entity"
                                targetProject=".\src">
                
                <property name="enableSubPackages" value="true" />
                
                <property name="trimStrings" value="true" />
            </javaModelGenerator>
    
            
            <sqlMapGenerator targetPackage="com.cvzhanshi.mybatis.dao"
                             targetProject=".\config">
                
                <property name="enableSubPackages" value="true" />
            </sqlMapGenerator>
    
            
            
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.cvzhanshi.mybatis.dao"
                                 targetProject=".\src">
                <property name="enableSubPackages" value="true" />
            </javaClientGenerator>
    
            
    
    
    
    
    
    
    
            
            <table tableName="dept" domainObjectName="Department"></table>
            <table tableName="employee" domainObjectName="Employee"></table>
        </context>
    </generatorConfiguration>

*  运行代码生成需要的文件

@Test
    	public void testMbg() 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);
    	}

> Context标签
> 
> targetRuntime=“MyBatis3“可以生成带条件的增删改查
> 
> targetRuntime=“MyBatis3Simple“可以生成基本的增删改查
> 
> 如果再次生成，建议将之前生成的数据删除，避免xml向后追加内容出现的问题

基本的crud测试

@Test
    	public void testMyBatis3Simple() throws IOException{
        
    		SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
    		SqlSession openSession = sqlSessionFactory.openSession();
    		try{
        
    			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
    			List<Employee> list = mapper.selectAll();
    			for (Employee employee : list) {
        
    				System.out.println(employee.getId());
    			}
    		}finally{
        
    			openSession.close();
    		}
    	}

带条件的crud

@Test
    	public void testMyBatis3() throws IOException{
        
    		SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
    		SqlSession openSession = sqlSessionFactory.openSession();
    		try{
        
    			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
    			//xxxExample就是封装查询条件的
    			//1、查询所有
    			//List<Employee> emps = mapper.selectByExample(null);
    			//2、查询员工名字中有e字母的，和员工性别是1的
    			//封装员工查询条件的example
    			EmployeeExample example = new EmployeeExample();
    			//创建一个Criteria，这个Criteria就是拼装查询条件
    			//select id, last_name, email, gender, d_id from tbl_employee
    			//WHERE ( last_name like ? and gender = ? ) or email like "%e%"
    			EmployeeExample.Criteria criteria = example.createCriteria();
    			criteria.andLastNameLike("%e%");
    			criteria.andGenderEqualTo("1");
    
    //			EmployeeExample.Criteria criteria2 = example.createCriteria();
    //			criteria2.andEmailLike("%e%");
    //			example.or(criteria2);
    
    			List<Employee> list = mapper.selectByExample(example);
    			for (Employee employee : list) {
        
    				System.out.println(employee.getId());
    			}
    
    		}finally{
        
    			openSession.close();
    		}
    	}

> 总结：如果条件是and就在同一个Criteria对象中addxxxxx（）；如果是or就在生成一个Criteria对象，然后
> 
> example.or(criteria2);

[mbg]: https://github.com/mybatis/generator/releases/tag/mybatis-generator-1.4.0
[2021050816404355.png]: https://img-blog.csdnimg.cn/2021050816404355.png