java读取接口返回的json数据 （二）

package cn.wangshiyu777;
 
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
 
import org.junit.Test;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
 
 
 
public class JsonUtil {
  public static String loadJson(String url) throws Exception {
    //读取url,返回json串
    StringBuilder json = new StringBuilder();
    URL oracle = new URL(url);
    URLConnection yc = oracle.openConnection();
    BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream()));
    String inputLine = null;
    while((inputLine = in.readLine()) != null){
      json.append(inputLine);
    }
    in.close();
    
    return json.toString();
  }
  public static void main(String[] args) throws Exception {
    String url = "http://api.geonames.org/citiesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&lang=de&username=demo";
    //
    String json = loadJson(url);
    System.out.println(json);
    //获取json字符串中key对应的值
//    JsonParser jsonParser = new JsonParser();
    //将json字符串转化成json对象
//    JsonObject jObject = jsonParser.parse(json).getAsJsonObject();
    //获取对应字段值
//    String topic = jObject.get("Topic").getAsString();
//    System.out.println("Topic:"+topic);
    
//    第二种
//    JSONArray js = new JSONArray(json);
//    for (int i = 0; i < js.length(); i++) {
//      JSONObject json1 = js.getJSONObject(i);
//      System.out.println(json1.getString("Topic"));
//    }
    
    //第三种有错
//    JSONObject jsonObject = JSON.parseObjet(json);
//    String r = jsonObject.getString("Topic");
//    System.out.println(r);
    
    //第四种
//    JSONObject json1 = new JSONObject(json);
//    String Value = json1.getString("Topic");
//    System.out.println(Value);
    
    JSONArray jsonArray = JSONArray.fromObject(json);
 
    //JSONArray jsonArray = JSONArray.fromObject(URLDecoder.decode(request.getParameter("rejectAry"),"UTF-8"));
    System.out.println(jsonArray);
    for (int i = 0; i < jsonArray.length(); i++) {
      JSONObject json1 = jsonArray.getJSONObject(i);
      System.out.println(json1.getString("Topic"));
    }
  }
  @Test
  public void aaa() throws UnsupportedEncodingException {
    String string  = new String("北京".getBytes("utf-8"),"unicode");
    String aString = new String(string.getBytes("unicode"), "utf-8");
    System.out.println(aString);
  }
}