MyBatis中SQL映射文件中foreach的具体使用

阳光穿透心脏的1/2处 2023-06-06 12:17 26阅读 0赞

**一、SQL映射文件**

<select id="queryEmployeeByForeach" resultType="Employee">
    		select * from employee where id in
    		
    		<foreach collection="list" item="id" open="(" separator="," close=")">
    			#{id}
    		</foreach>
    				
    		<foreach collection="array" item="id" open="(" separator="," close=")">
    			#{id}
    		</foreach>
    		
    		<foreach collection="array" item="emp" open="(" separator="," close=")">
    			#{emp.id}
    		</foreach> 
    	</select>

**二、编写接口中对应的方法**

public List<Employee> queryEmployeeByForeach(List<Integer> idList);
    public List<Employee> queryEmployeeByForeach(int[] idArray);
    public List<Employee> queryEmployeeByForeach(Employee[] empArray);

**三、测试**

private static SqlSession session;
    	static { 
    		try { 
    			Reader reader = Resources.getResourceAsReader("myBatis.xml");
    			SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    			SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(reader);
    			session = sqlSessionFactory.openSession();
    // sqlSessionFactory.openSession(true); //事务自动提交，一般不用
    		} catch (IOException e) { 
    			e.printStackTrace();
    		}
    	}
    
    	//使用Foreach标签
    	public static void queryEmployeeByForeach() { 
    		EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
    		List<Integer> idList=new ArrayList<>();
    		idList.add(1);
    		idList.add(2);
    		idList.add(3);
    // int[] idArray=new int[] {1,2,3};
    // Employee employee1 = new Employee();
    // Employee employee2 = new Employee();
    // Employee employee3 = new Employee();
    // employee1.setId(1);
    // employee2.setId(2);
    // employee3.setId(3);
    // Employee[] empArray=new Employee[] {employee1,employee2,employee3};
    		List<Employee> empList = mapper.queryEmployeeByForeach(idList);
    // List<Employee> empList = mapper.queryEmployeeByForeach(idArray);
    // List<Employee> empList = mapper.queryEmployeeByForeach(empArray);
    		System.out.println(empList);
    	}
    
    	public static void main(String[] args) throws IOException { 
    		queryEmployeeByForeach();
    	}