一：解析普通json

      1：不带转化字符

       格式{"type":"ONLINE_SHIPS","message":{"currentTime":1400077615368,"direction":0,"id":1,"latitude":29.5506,"longitude":106.6466}}      

JSONObject jsonObject = new JSONObject(jsonstr).getJSONObject("message");
					System.out.println("currentTime:"+jsonObject.get("currentTime"));	
					System.out.println("direction:"+jsonObject.get("direction"));	
					System.out.println("latitude:"+jsonObject.get("latitude"));	
					System.out.println("longitude:"+jsonObject.get("longitude"));

      jsonarray    

JSONObject jo = ja.getJSONArray("cargoList").getJSONObject(0);

    2:带转义字符的json格式

    {"type":"ONLINE_SHIPS","message":"{\"currentTime\":1400077615368,\"direction\":0,\"id\":1,\"latitude\":29.5506,\"longitude\":106.6466}"}

     其实也很简单，先把它转化成字符串就可以了

JSONObject jsonObject = new JSONObject(jsonstr);
					//先通过字符串的方式得到,转义字符自然会被转化掉
					String jsonstrtemp = jsonObject.getString("message");										
					System.out.println("message:"+jsonstrtemp);	
					jsonObject = new JSONObject(jsonstrtemp);
					System.out.println("currentTime:"+jsonObject.get("currentTime"));	
					System.out.println("direction:"+jsonObject.get("direction"));	
					System.out.println("latitude:"+jsonObject.get("latitude"));	
					System.out.println("longitude:"+jsonObject.get("longitude"));

二：遍历Json对象

     

JSONObject ports = ja.getJSONObject("ports");
				Iterator<String> keys = ports.keys();
				while(keys.hasNext()){  
		           String key=keys.next();  
		           String value = ports.getString(key);
		        }

三：使用Gjson,json与对象相互转化

使用Gson轻松将java对象转化为json格式

 String json = gson.toJson(Object);//得到json形式的字符串

 User user = gson.fromJson(json,User.class);//得到对象

转化成list

import java.util.List;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.lc.function.Action;
import com.lc.models.Groups;

public class MapSearch {

	private void ParseData(String _data)
	{
		Gson gson = new Gson();
		List<Groups> ps = gson.fromJson(_data, new TypeToken<List<Groups>>(){}.getType());		
		System.out.println(ps.get(0).getGroup_name());
	}
}