mybatis學習四 列表查詢不一樣方式實現

若是有問題,能夠參考前面的博客 ###1. 普通的方式 ####1.1 接口文件添加方法

public List<Employeer> findEmployeer();

####1.2 添加***mapper.xml文件的sql語句

<select id="findEmployeer" resultType="Employeer">
    	 select* from `t_employeer`
     </select>

####1.3 編寫測試類

public static void main(String[] args) {
		//test1();
		SqlSession session = null;
		try {
			session = sqlSessionFactory.openSession();
			EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
			List<Employeer> lists=employeerMapper.findEmployeer();
			for (Employeer employeer : lists) {
				System.out.println(employeer.toString());
			}
            session.commit() ;  		
		} finally {
			session.close();
		}

	}

###2.使用resultMap

2.1 編寫resultMap

其實能夠多表來關聯查詢,只須要修改實體類和sql就能夠了

<!-- 定義數據庫字段與實體對象的映射關係 -->
 <resultMap type="Employeer" id="resultMap">
    <id property="employeer_id" column="employeer_id"/> 
    <result property="employeer_name" column="employeer_name"/>
    <result property="employeer_age" column="employeer_age"/>
    <result property="employeer_department" column="employeer_department"/>
    <result property="employeer_worktype" column="employeer_worktype"/>
 </resultMap>

id、result是最簡單的映射，id爲主鍵映射；result其餘基本數據庫表字段到實體類屬性的映射。

2.2 編寫查詢語句

<!-- 返回list 的select 語句，注意 resultMap 的值是指向前面定義好的 -->
    <select id="findEmployeerByName" parameterType="string" resultMap="resultMap">
        select * from `t_employeer` where employeer_name like #{employeer_name}
    </select>

2.3 在EmployeerMapper 接口中增長方法

/**
	 * 注意要和Employeer.xml的方法名對應
	 */
	public List<Employeer> findEmployeerByName(String employeer_name);

2.4 編寫測試類

/**
	 * 查詢列表
	 */
	public static List<Employeer> getEmployeerList(String employeer_name){
		SqlSession session = null;
		 List<Employeer> employeers=null;
		try {
			session = sqlSessionFactory.openSession(); 
			EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
			 employeers = employeerMapper.findEmployeerByName(employeer_name);	
            session.commit() ;  		
		} finally {
			session.close();
		}
		return employeers;
   
    }
	public static void main(String[] args) {							
		List<Employeer> employeers=getEmployeerList("張三");
		 for(Employeer employeer:employeers){
             System.out.println(employeer);
         }

	}