Question

我正在使用httpurlconnection测试android中的长轮询，但应用程序会因错误nullpointerexception而崩溃。

07-21 07:17:42.469: V/Online Connection(27092): Bufferd called 07-21 07:17:42.469: V/Online Connection(27092): data called 07-21 07:17:42.471: V/Online Connection(27092): Get data called 07-21 07:17:42.471: E/Online Connection(27092): Error calledSocket closed 07-21 07:17:42.472: V/Online Connection(27092): Get data called 07-21 07:17:42.473: V/Online Connection(27092): Connect called 07-21 07:17:42.479: V/Online Connection(27092): Connect called 07-21 07:17:42.832: V/Online Connection(27092): Bufferd called 07-21 07:17:42.832: V/Online Connection(27092): data calledok 07-21 07:17:44.147: V/Online Connection(27092): Bufferd called 07-21 07:17:44.147: V/Online Connection(27092): data called 07-21 07:17:44.148: V/Online Connection(27092): Get data called 07-21 07:17:44.149: V/Online Connection(27092): Connect called 07-21 07:17:44.152: E/Online Connection(27092): Error calledSocket closed 07-21 07:17:44.205: E/AndroidRuntime(27092): FATAL EXCEPTION: Thread-34364 07-21 07:17:44.205: E/AndroidRuntime(27092): Process: in.briskjab.reactor, PID: 27092 07-21 07:17:44.205: E/AndroidRuntime(27092): java.lang.NullPointerException 07-21 07:17:44.205: E/AndroidRuntime(27092): at com.android.okhttp.internal.http.HttpEngine.readResponse(HttpEngine.java:632) 07-21 07:17:44.205: E/AndroidRuntime(27092): at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:347) 07-21 07:17:44.205: E/AndroidRuntime(27092): at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:296) 07-21 07:17:44.205: E/AndroidRuntime(27092): at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:179) 07-21 07:17:44.205: E/AndroidRuntime(27092): at in.bb.longpolling.onlineconnection.httpconnection(onlineconnection.java:89) 07-21 07:17:44.205: E/AndroidRuntime(27092): at in.bb.longpolling.onlineconnection.SGData(onlineconnection.java:39) 07-21 07:17:44.205: E/AndroidRuntime(27092): at in.bb.GActivity$6.run(GActivity.java:974) 07-21 07:17:44.205: E/AndroidRuntime(27092): at java.lang.Thread.run(Thread.java:841)

代码：

> `public String SGData(String data,int option) { //Send And Get Data
    String newdataloc;
    try {
        newdataloc = URLEncoder.encode(data,"UTF-8");
    } catch(UnsupportedEncodingException e){
        Log.e("Online Connection","Error:Encoding="+e.getMessage());
    }

    return httpconnection(data,option);
}

private String httpconnection(String postData,int option){
    Log.v("Online Connection","Get data called");
    String webPage = "",resdata="";
    try{
           urlc = new URL(this.url);
           urlConnection = (HttpURLConnection) urlc.openConnection();
           Log.v("Online Connection","Connect called");
        if(option==1){ //only get data
            urlConnection.connect();// it gives error "already connected" if you are using it with post or get method.Uncomment and comment 'post and get method area' 
        }
        if(option==2){
            //POST METHOD AREA
            urlConnection.setDoOutput(true);
            urlConnection.setRequestMethod("POST");
            urlConnection.setRequestProperty("Content-Length", Integer.toString(postData.getBytes().length));
            urlConnection.setUseCaches(false);
            OutputStream out = urlConnection.getOutputStream();
            out.write(postData.getBytes());
            out.close();
        }
        if(option==3){
            urlConnection.setDoOutput(true);
            urlConnection.setRequestMethod("GET");
            urlConnection.setRequestProperty("Content-Length", Integer.toString(postData.getBytes().length));
            urlConnection.setUseCaches(false);
            OutputStream out = urlConnection.getOutputStream();
            out.write(postData.getBytes());
            out.close();
        }
           InputStream is = urlConnection.getInputStream();
           BufferedReader reader =new BufferedReader(new InputStreamReader(is, "UTF-8"));
           Log.v("Online Connection","Bufferd called");
           while ((resdata = reader.readLine()) != null){
              webPage += resdata + "\n";
           } 
           is.close();
           Log.v("Online Connection","data called" + webPage);
       } catch(IOException e){
           Log.e("Online Connection","Error called" + e.getMessage());
           }
    finally {
        urlConnection.disconnect(); 
    }
    return webPage;
}
calling Code:->
String mResponse=null;
                do{
                    mResponse = online_serlst.SGData("op=3&server_name="+mServerName+"&userid="+mUserid+"&color="+DeviceCurrentPlayer+"&lr="+lr+"&ld="+pd, 2);
                }while(!mResponse.toString().trim().equals("ok"));`

如果用户通过简单的单一请求点击提交按钮，我会将数据从我的游戏发送到服务器，如果有新的更新，则使用长轮询继续检查服务器的新更新.4-5分钟应用程序崩溃后使用nullpointexception。对单个请求和长轮询使用不同的线程。

在android 4.4.2 moto g设备上测试应用程序。

Answer 1

根据我的理解，这可能是因为它正在关闭/终止连接池。您正在使用2个线程。一个是向服务器发送请求＆amp;其次是从服务器获取更新响应。

我认为，如果您只想更新自己的用户界面，则可以选择＆＃34;服务处理程序＆＃34;。当您希望频繁更新UI时，这是更新UI的最佳方式。

getInputStream中的httpurlconnection NullPointerException

1 个答案: