JAVA的JSON示例

在ECLIPSE中的某个工程使用json，需要导入额外的json包，比如json-20090211.jar。从网上下到这个库之后，放到工程目录下，在project导入的方法是：点击工程右键-》属性-》Java build path-》libraries，再点击右边的add external JARs，选中刚才放置的Jar包就可以了。

       比如如下的工程，从网站地理位置数据中返回特定数据

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.nio.charset.Charset;

import org.json.JSONException;
import org.json.JSONObject;
/**
 * java根据url获取json对象
 * @author openks
 * @since 2013-7-16
 * 需要添加java-json.jar才能运行
 */
public class TestJava {

  private static String readAll(Reader rd) throws IOException {
    StringBuilder sb = new StringBuilder();
    int cp;
    while ((cp = rd.read()) != -1) {
      sb.append((char) cp);
    }
    return sb.toString();
  }

  public static JSONObject readJsonFromUrl(String url) throws IOException, JSONException {
    InputStream is = new URL(url).openStream();
    try {
      BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
      String jsonText = readAll(rd);
      JSONObject json = new JSONObject(jsonText);
      return json;
    } finally {
      is.close();
     // System.out.println("同时 从这里也能看出 即便return了，仍然会执行finally的！");
    }
  }

  public static void main(String[] args) throws IOException, JSONException {
   //这里调用百度的ip定位api服务 详见 http://api.map.baidu.com/lbsapi/cloud/ip-location-api.htm
    JSONObject json = readJsonFromUrl("http://api.map.baidu.com/location/ip?ak=F454f8a5efe5e577997931cc01de3974&ip=202.198.16.3");
    System.out.println(json.toString());
    System.out.println();
    System.out.println(((JSONObject) json.get("content")).get("address"));
  }
}

执行结果是

{"content":{"point":{"y":"5419815.34","x":"13950002.65"},"address":"吉林省长春市","address_detail":{"street":"","province":"吉林省","city_code":53,"street_number":"","district":"","city":"长春市"}},"status":0,"address":"CN|吉林|长春|None|CERNET|0|0"}

吉林省长春市

=============================================

另外有遇到这样的写法 (不知道对不对):

static private String weater_url = "http://www.weather.com.cn/data/sk/101010100.html";

URL req_url = new URL(weater_url);

HttpURLConnection urlConn = (HttpURLConnection)req_url.openConnection();

urlConn.setConnectTimeout(5*1000);
urlConn.connect();

//if(urlConn.getResponseCode() == HTTP_200)
                {
                    BufferedReader reader = new BufferedReader (new InputStreamReader(urlConn.getInputStream(),"utf-8"));
                //    Log.v(TAG,"reader= "+ reader);
                }