AsyncHttpRequest.java

package com.ta.util.http;

import java.io.File;
import java.io.IOException;
import java.net.ConnectException;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpRequestRetryHandler;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.impl.client.AbstractHttpClient;
import org.apache.http.protocol.HttpContext;

public class AsyncHttpRequest implements Runnable
{
	private final AbstractHttpClient client;
	private final HttpContext context;
	private final HttpUriRequest request;
	private final AsyncHttpResponseHandler responseHandler;
	private boolean isBinaryRequest;
	private int executionCount;

	public AsyncHttpRequest(AbstractHttpClient client, HttpContext context,
			HttpUriRequest request, AsyncHttpResponseHandler responseHandler)
	{
		this.client = client;
		this.context = context;
		this.request = request;
		this.responseHandler = responseHandler;
		if (responseHandler instanceof BinaryHttpResponseHandler)
		{
			this.isBinaryRequest = true;
		} else if (responseHandler instanceof FileHttpResponseHandler)
		{
			FileHttpResponseHandler fileHttpResponseHandler = (FileHttpResponseHandler) responseHandler;
			File tempFile = fileHttpResponseHandler.getTempFile();

			if (tempFile.exists())
			{

				long previousFileSize = tempFile.length();
				fileHttpResponseHandler.setPreviousFileSize(previousFileSize);
				this.request.setHeader("RANGE", "bytes=" + previousFileSize
						+ "-");
			}

		}
	}

	@Override
	public void run()
	{
		try
		{
			if (responseHandler != null)
			{
				responseHandler.sendStartMessage();
			}

			makeRequestWithRetries();
			if (responseHandler != null)
			{
				responseHandler.sendFinishMessage();
			}

		} catch (IOException e)
		{
			if (responseHandler != null)
			{
				responseHandler.sendFinishMessage();
				if (this.isBinaryRequest)
				{
					responseHandler.sendFailureMessage(e, (byte[]) null);
				} else
				{
					responseHandler.sendFailureMessage(e, (String) null);
				}
			}
		}
	}

	private void makeRequest() throws IOException
	{
		if (!Thread.currentThread().isInterrupted())
		{
			try
			{
				HttpResponse response = client.execute(request, context);
				if (!Thread.currentThread().isInterrupted())
				{
					if (responseHandler != null)
					{
						responseHandler.sendResponseMessage(response);
					}
				} else
				{
					// TODO: should raise InterruptedException? this block is
					// reached whenever the request is cancelled before its
					// response is received
				}
			} catch (IOException e)
			{
				if (!Thread.currentThread().isInterrupted())
				{
					throw e;
				}
			}
		}
	}

	private void makeRequestWithRetries() throws ConnectException
	{
		// This is an additional layer of retry logic lifted from droid-fu
		// See:
		// https://github.com/kaeppler/droid-fu/blob/master/src/main/java/com/github/droidfu/http/BetterHttpRequestBase.java
		boolean retry = true;
		IOException cause = null;
		HttpRequestRetryHandler retryHandler = client
				.getHttpRequestRetryHandler();
		while (retry)
		{
			try
			{
				makeRequest();
				return;
			} catch (UnknownHostException e)
			{
				if (responseHandler != null)
				{
					responseHandler.sendFailureMessage(e, "can't resolve host");
				}
				return;
			} catch (SocketException e)
			{
				// Added to detect host unreachable
				if (responseHandler != null)
				{
					responseHandler.sendFailureMessage(e, "can't resolve host");
				}
				return;
			} catch (SocketTimeoutException e)
			{
				if (responseHandler != null)
				{
					responseHandler.sendFailureMessage(e, "socket time out");
				}
				return;
			} catch (IOException e)
			{
				cause = e;
				retry = retryHandler.retryRequest(cause, ++executionCount,
						context);
			} catch (NullPointerException e)
			{
				// there's a bug in HttpClient 4.0.x that on some occasions
				// causes
				// DefaultRequestExecutor to throw an NPE, see
				// http://code.google.com/p/android/issues/detail?id=5255
				cause = new IOException("NPE in HttpClient" + e.getMessage());
				retry = retryHandler.retryRequest(cause, ++executionCount,
						context);
			}
		}

		// no retries left, crap out with exception
		ConnectException ex = new ConnectException();
		ex.initCause(cause);
		throw ex;
	}
}