json - Android HTTPPost Returns Error "Method not allowed."

Question

I'm coding an Android 2.2 app that POSTs a json stringentity to a ReSTfull web service.

Fiddler calls to the web service with identical Json return as expected, and an aspx web application with identical Json returns as expected.

When I look at the server logs, I can see that the server is responding to an initial POST verb with a 307 redirect, then immediately a GET and 405 error.

Fiddler and the aspx application log a POST with a 307 redirect, then immediately another POST and a 200 OK.

What is going on?

This is the main activity:

package com.altaver.android_PostJson2;

import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class PostJson extends Activity {
     private static final String TAG = "MainActivity";
     private static final String URL = "http://web2.altaver.com/sdz/avReSTfulLogin1";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        JSONObject jsonObjSend = new JSONObject();

        try {
         jsonObjSend.put("Pass", "sz");
         jsonObjSend.put("User", "szechman");


         Log.i(TAG, jsonObjSend.toString(2));

        } catch (JSONException e) {
            e.printStackTrace();
        }

        JSONObject jsonObjRecv = HttpClient.SendHttpPost(URL, jsonObjSend);            

//examine JSONObject later
    }
}

This is the class code doing the web service call:

package com.altaver.android_PostJson2;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.params.HttpClientParams;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONObject;

import android.util.Log;

public class HttpClient {

    private static final String TAG = "HttpClient";


    public static JSONObject SendHttpPost(String URL, JSONObject jsonObjSend) {

          try {
           DefaultHttpClient httpclient = new DefaultHttpClient();

           HttpClientParams.setRedirecting(httpclient.getParams(), true);

           //added cookie policy, wild shot in the dark
           //httpclient.getParams().setParameter(ClientPNames.COOKIE_POLICY, >CookiePolicy.RFC_2109);

           HttpPost httpPostRequest = new HttpPost(URL);

           StringEntity se;
           se = new StringEntity(jsonObjSend.toString());

           // Set HTTP parameters
           httpPostRequest.setEntity(se);

           //httpPostRequest.setHeader("User-Agent", >"com.altaver.android_PostJson2");
           httpPostRequest.setHeader("User-Agent", "Mozilla/5.0 (Windows; U; >Windows NT 5.1; en-US; rv:1.9.2.3) Gecko/20100401");

           httpPostRequest.setHeader("Accept", "application/json");
           httpPostRequest.setHeader("Content-Type", "application/json");

           long t = System.currentTimeMillis();
           HttpResponse response = (HttpResponse) >httpclient.execute(httpPostRequest);
           Log.i(TAG, "HTTPResponse received in [" + >(System.currentTimeMillis()-t) + "ms]");

           HttpEntity entity = response.getEntity();

           if (entity != null) {
            InputStream instream = entity.getContent();
            Header contentEncoding = response.getFirstHeader("Content-Encoding");


            String resultString= convertStreamToString(instream);
            instream.close();
            resultString = resultString.substring(1,resultString.length()-1); // >remove wrapping "[" and "]"

            JSONObject jsonObjRecv = new JSONObject(resultString);
            Log.i(TAG,"<jsonobject>
"+jsonObjRecv.toString()+"
</jsonobject>");

            return jsonObjRecv;
           } 

          }
          catch (Exception e)
          {
           e.printStackTrace();
          }
          return null;
         }

    private static String convertStreamToString(InputStream is) {
          /*
           * To convert the InputStream to String we use the >BufferedReader.readLine()
           * method. We iterate until the BufferedReader return null which means
           * there's no more data to read. Each line will appended to a >StringBuilder
           * and returned as String.
           * 
           * (c) public domain: http://senior.ceng.metu.edu.tr/2009/praeda/2009/01>/11/a-simple-restful-client-at-android/
           */
          BufferedReader reader = new BufferedReader(new InputStreamReader(is));
          StringBuilder sb = new StringBuilder();

          String line = null;
          try {
           while ((line = reader.readLine()) != null) {
            sb.append(line + "
");
           }
          } catch (IOException e) {
           e.printStackTrace();
          } finally {
           try {
            is.close();
           } catch (IOException e) {
            e.printStackTrace();
           }
          }
          return sb.toString();
    }
}

Answer 1

Putting a '/' at the end of URL causes the redirect to happen because your server likes urls that end in '/'. POST is fully supported by the URL your server redirects you to, but the client is executing a GET request when it behaves according to your setRedirecting() call (cURL does the same exact thing with the -L switch) The fix is to either put a '/' at the end of URL, or to grab the Location header from the response yourself and then initiate another POST request manually.

This can be observed in wireshark. You can test the theory by trying to perform a GET request with your browser to the URL with a slash appended to it. That will cause the browser to get a 405. Here's the fixed code for Android, this code uses the simple fix of appending a '/' to the URL (not production ready):

 package com.altaver.demo;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.HttpResponseException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.params.HttpClientParams;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class AltaVerDemoActivity extends Activity {
    private static final String TAG = "MainActivity";
    private static final String URL = "http://96.56.2.188/sdz/avReSTfulLogin1/";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        JSONObject jsonObjSend = new JSONObject();
        try {
            jsonObjSend.put("Pass", "sz");
            jsonObjSend.put("User", "szechman");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        HttpClient client = new DefaultHttpClient();
        HttpPost httpPostRequest = new HttpPost(URL);
        httpPostRequest.setHeader("User-Agent", "com.altaver.android_PostJson2");
        httpPostRequest.setHeader("Accept", "application/json");
        httpPostRequest.setHeader("Content-Type", "application/json");
        StringEntity se = null;
        try {
            se = new StringEntity(jsonObjSend.toString());
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        httpPostRequest.setEntity(se);
        HttpResponse response = null;
        try {
            response = client.execute(httpPostRequest);
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            Toast.makeText(getApplicationContext(),
                    "Please check your internet connection",
                    Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        BasicResponseHandler responseHandler = new BasicResponseHandler();
        String strResponse = null;
        if (response != null) {
            try {
                strResponse = responseHandler.handleResponse(response);
            } catch (HttpResponseException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        Log.e("AltaVerDemoActivity", "Response: " + strResponse);
    }
}