一、通過Map.Keyset遍歷key和value,普遍使用，二次取值

//定義一個Map集合
		Map<String, String>map=new HashMap<String, String>();
		//給map結合賦值
		map.put("k1", "v1");
		map.put("k2", "v2");
		map.put("k3", "v3");
		map.put("k4", "v4");
		//遍歷
		for(String key:map.keySet()){
			System.out.println("Key="+key+"\tvalue="+map.get(key));
		}
 

		Iterator<Map.Entry<String, String>>it=map.entrySet().iterator();
		while(it.hasNext()){
			Map.Entry<String, String>entry=it.next();
			System.out.println("key="+entry.getKey()+"\tvalue="+entry.getValue());
		}

		for(Map.Entry<String, String> entry:map.entrySet()){
			System.out.println("key="+entry.getKey()+"\tvalue="+entry.getValue());
		}

		for(String v:map.values()){
			System.out.println("value="+v);
		}