Android HttpPost exception null

Question

I am getting an exception caught in my Android project while making an HttpPost call and I cannot figure out why. Here is the start of the method that makes the network call:

try {


        this.httpClient = new DefaultHttpClient();
        httpPost = new HttpPost(url);

        if (json != null && json != "") {
            httpPost.setEntity(new ByteArrayEntity(json.getBytes("UTF8")));
            httpPost.setHeader("Content-type", "application/json");
            if(token!=null) {
                //httpPost.setHeader("Authorization", "Basic VEU5SFNVNWZWRmxRUlY5RFZWTlVUMDFGVWpwcWFXMXRlV1JoWjJobGNrQm5iV0ZwYkM1amIyMDZNVEV4TVE9PQ==");
                httpPost.setHeader("Authorization", "Basic " + token);
            }
        }



        HttpParams httpParameters = new BasicHttpParams();
        // Set the timeout in milliseconds until a connection is established.
        // The default value is zero, that means the timeout is not used. 
        int timeoutConnection = 15000;
        HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
        // Set the default socket timeout (SO_TIMEOUT) 
        // in milliseconds which is the timeout for waiting for data.
        int timeoutSocket = 15000;
        HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
        httpClient.setParams(httpParameters);


        httpResponse = httpClient.execute(httpPost);

The last line is the one where the exception is caught. I tried logging out exception.getMessage(), but that is null. Here is the stack backtrace:

java.net.PlainSocketImpl.read(PlainSocketImpl.java:492)
java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:46)
java.net.PlainSocketImpl$PlainSocketInputStream.read(PlainSocketImpl.java:241)
org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer(AbstractSessionInputBuffer.java:103)
org.apache.http.impl.io.AbstractSessionInputBuffer.readLine(AbstractSessionInputBuffer.java:191)
org.apache.http.impl.conn.DefaultResponseParser.parseHead(DefaultResponseParser.java:82)
org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:174)
org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:180)
org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:235)
org.apache.http.impl.conn.AbstractClientConnAdapter.receiveResponseHeader(AbstractClientConnAdapter.java:259)
org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:279)
org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:121)
org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:428)
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:670)
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
com.arcmobileapp.web.WebServices.getResponse(WebServices.java:106)
com.arcmobileapp.web.WebServices.createReview(WebServices.java:601)
com.arcmobileapp.web.SubmitReviewTask.performTask(SubmitReviewTask.java:59)
com.arcmobileapp.web.SubmitReviewTask.doInBackground(SubmitReviewTask.java:47)
com.arcmobileapp.web.SubmitReviewTask.doInBackground(SubmitReviewTask.java:1)
android.os.AsyncTask$2.call(AsyncTask.java:287)
java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
java.util.concurrent.FutureTask.run(FutureTask.java:137)
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
java.lang.Thread.run(Thread.java:856)

Any idea what could be causing the exception? It does not happen every time, it seems to be intermittent (network?).

Thanks in advance.

Answer 1

test this code:

public class HttpConnectionTask
{
    public static final int RESPONSE_OK = 0;
    public static final int RESPONSE_ERROR = 1;    

    private String body = null;
    private String strUrl;
    private int responsCode;
    private List<NameValuePair> postData = null;

    public HttpConnectionTask(String strUrl)
    {
        this.strUrl = strUrl;
    } 

    public HttpConnectionTask(String strUrl, List<NameValuePair> postData)
    {
        this.strUrl = strUrl;
        this.postData = postData;
    } 

    public void run() 
    {               
        try
        {           
            this.responsCode = RESPONSE_OK;

            HttpClient client = new DefaultHttpClient(); 
            HttpResponse response = null;

            if(this.postData == null)
            {
                HttpGet get = new HttpGet(this.strUrl);             
                response = client.execute(get); 
            }
            else
            {
                HttpPost postMethod = new HttpPost(this.strUrl);
                postMethod.setEntity(new UrlEncodedFormEntity(this.postData, "UTF-8"));
                response = client.execute(postMethod);
            }

            // Get the response
            BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

            this.body = "";

            char[] dataChunk = new char[1024];            
            StringBuffer dataBuffer = new StringBuffer();

            int readSize = 0;

            while((readSize = rd.read(dataChunk)) >= 0)
            {                
                dataBuffer.append(dataChunk, 0, readSize);                
            }

            this.body = dataBuffer.toString().trim();                       
        }        
        catch (Exception ex)
        {            
            this.responsCode = RESPONSE_ERROR;
        }                                               
    }

    public String getBody()
    {
        return this.body;
    }

    public int getResponse()
    {
        return this.responsCode;
    }
}

and use this class :

String url = "Your url" + "?exam1=1"; //for get data                                                    

List<NameValuePair> postData = new ArrayList<NameValuePair>();          
postData.add(new BasicNameValuePair("test1", "123")); //for post data
postData.add(new BasicNameValuePair("test2", "456")); //for post data

HttpConnectionTask httpPost = new HttpConnectionTask(url, postData);
httpPost.run();

Answer 2

java.net.PlainSocketImpl This exception usually occurs when there is no service listening on the port you are trying to connect to.

Recheck the below three things

1) Host name and port you're trying to connect to.

2) The server side has managed to start listening correctly.

3) There's no firewall blocking the connection.