ibatis Tips 之 java.util.Map作为parameterClass和resultClass

1.Map作为parameterClass

映射文件：

<!--use Map type as parameterClass-->
		<select id="getProduct-Map" parameterClass="java.util.Map" resultMap="get-product-result">
			<![CDATA[
				select * from t_product
				where prd_id=#id# and prd_description=#description#
			]]>
		</select>

 DAO层：

/**
	 * java.util.Map作为parameterClass
	 */
	public Product getProductMap(Map map) throws SQLException {
		init();
		Product product = (Product)sqlMapClient.queryForObject("getProduct-Map", map);
		return product;
	}

 Test类：

public void getProductMap() throws SQLException{
		Map map = new HashMap();
		map.put("id", new Integer(1));
		map.put("description", "basketball");
		Product product = productDao.getProductMap(map);
		System.out.println(product);
	}

 结果：

id:1
description:basketball
price206.99

 

 

2.Map作为resultClass

映射文件：

<resultMap id="get-product-map" class="java.util.HashMap">
			<result property="id" column="prd_id"/>
			<result property="description" column="prd_description"/>
			<result property="price" column="prd_price"/>
		</resultMap>

<!--START  use Map type as resultClass,MUST use java.util.HashMap instead java.util.Map-->
		<select id="getProdcut-MapResult" resultClass="java.util.HashMap
">
			<![CDATA[
				select * from t_product
			]]>
		</select>
		
		<select id="getProductUseMap-resultMap" resultMap="get-product-map">
			<![CDATA[
				select * from t_product
			]]>
		</select>
		<!-- END  -->

 DAO层：

/**
	 * java.util.Map作为resultClass
	 */
	public List getProductMapResult() throws SQLException {
		init();
		List list = sqlMapClient.queryForList("getProdcut-MapResult");
		return list;
		
	}


	public List getProductUseMapByResultMap() throws SQLException {
		init();
		List list = sqlMapClient.queryForList("getProductUseMap-resultMap");
		return list;
	}

 Test类：

public void getProductMapResult() throws SQLException{
		Map map = null;
		List list = productDao.getProductMapResult();
		for(Iterator it=list.iterator(); it.hasNext();) {
			//List里存放的是java.util.Map类型
			Object obj = (Object)it.next();
			System.out.println(obj.getClass());
			System.out.println(obj);
		}
	}
	
	public void getProductUseMapByResultMap() throws SQLException {
		Map map = null;
		List list = productDao.getProductUseMapByResultMap();
		for(Iterator it=list.iterator(); it.hasNext();) {
			//List里存放的是java.util.Map类型
			Object obj = (Object)it.next();
			System.out.println(obj.getClass());
			System.out.println(obj);
		}
	}

 

结果：

class java.util.HashMap
{prd_id=1, prd_price=206.99, prd_description=basketball}
class java.util.HashMap
{prd_id=2, prd_price=106.99, prd_description=football}
class java.util.HashMap
{price=206.99, description=basketball, id=1}
class java.util.HashMap
{price=106.99, description=football, id=2}

 

 

注意： Map作为resultClass时，必须指定具体的实现类，比如java.util.HashMap,否则会报错

Caused by: java.lang.RuntimeException: JavaBeansDataExchange could not instantiate result class.  Cause: java.lang.InstantiationException: java.util.Map