Android Open Source - client-android Http Helper

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License

The source code is released under:

Apache License

Java Source Code

package com.qmonix.sdk.helpers;
//from w w  w. ja v  a  2s  .co m
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.http.client.HttpClient;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.HttpHost;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.entity.StringEntity;

import android.os.AsyncTask;

/* AsyncTask.execute() generated exceptions */
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.lang.InterruptedException;

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

import com.qmonix.sdk.helpers.exceptions.HttpHelperException;
import com.qmonix.sdk.utils.AsyncTaskResult;
import com.qmonix.sdk.QLog;


/**
 * HTTP helper class that deals with HTTP message transmission. If it is used from the main UI
 * thread {@link #uiPostMessage uiPostMessage} should be used. It uses {@link AsyncTask} to avoid
 * {@link android.os.NetworkOnMainThreadException NetworkOnMainThreadException}. Otherwise it is
 * advised to use {@link #postMessage postMessage}.
 */
public class HttpHelper {

  private String hostname;
  private int port;
  private URI httpPostUri;


  /**
   * Constructs a new http helper object using a specified server uri.
   *
   * @param uri server url.
   */
  public HttpHelper(String uri) throws URISyntaxException {
    this.httpPostUri = new URI(uri);
    this.hostname = this.httpPostUri.getHost();
    this.port = this.httpPostUri.getPort();
  }

  /**
   * Does the same as postMessage() except it allows to do network operations on main UI
   * thread.
   *
   * @param message message to bet sent to the server.
   * @return response from the server.
   * @see #postMessage
   */
  public String uiPostMessage(String message) throws HttpHelperException {
    String response = "";

    PostHttpMessage postHttp = new PostHttpMessage();
    postHttp.execute(message);
    try {
      AsyncTaskResult<Object> result = postHttp.get();
      if (result.isException() == false) {
        response = (String)result.getResult();

      } else {
        Exception e = result.getError();
        QLog.error(e.toString());
        throw new HttpHelperException(e.toString());
      }

    } catch(Exception e) {
      QLog.error(e.toString());
      throw new HttpHelperException(e.toString());
    }

    return response;
  }

  /**
   * Synchronously sends a HTTP POST message meaning that method waits until it receives
   * a response. The response message is returned. Assumes that a content is in JSON.
   *
   * @param message message to bet sent to the server.
   * @return response from the server.
   */
  public String postMessage(String message) throws HttpHelperException {
    HttpHost httpHost = new HttpHost(this.hostname, this.port, "http");
    HttpClient httpClient = new DefaultHttpClient();
    HttpPost httpPost = new HttpPost(this.httpPostUri);
    ResponseHandler<String> responseHandler = new BasicResponseHandler();
    String httpResponse = "";

    try {
      StringEntity se = new StringEntity(message);
      httpPost.setEntity(se);
      httpPost.setHeader("Accept", "application/json");
      httpPost.setHeader("Content-type","application/json");

      httpResponse = httpClient.execute(httpHost, httpPost, responseHandler);

    } catch (UnsupportedEncodingException e) {
      String msg = "Creating http post body entity failed: " + e;
      QLog.error(msg);
      throw new HttpHelperException(msg);

    } catch (IOException e) {
      String msg = "Sending message failed: " + e;
      QLog.error(msg);
      throw new HttpHelperException(msg);

    } catch (Exception e) {
      String msg = "Unknown error: " + e;
      QLog.error(msg);
      throw new HttpHelperException(msg);
    }

    return httpResponse;
  }


  /**
   * This is a helper class that allows to do network operations on the main UI thread.
   * It extends AsyncTask class which handles all thread associated activities.
   */
  private class PostHttpMessage extends AsyncTask<String, Void, AsyncTaskResult<Object>> {

    /**
     * Sends http POST message.
     *
     * @param msgs http messages to send. Only first array element, msgs[0], is used.
     * @return http response message on success, exception on failure.
     */
    protected AsyncTaskResult<Object> doInBackground(String... msgs) {
      AsyncTaskResult<Object> retval;

      try{
        String httpResponse = HttpHelper.this.postMessage(msgs[0]);
        retval = new AsyncTaskResult<Object>(httpResponse);

      } catch (Exception e) {
        QLog.error(e.toString());
        retval = new AsyncTaskResult<Object>(e);
      }

      return retval;
    }
  }
}

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