Java tutorial
/* Android Asynchronous Http Client Copyright (c) 2011 James Smith <james@loopj.com> http://loopj.com Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ package com.loopj.android.http.handler; import java.io.IOException; import java.io.InputStream; import java.net.URI; import org.apache.http.Header; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.StatusLine; import org.apache.http.client.HttpResponseException; import org.apache.http.util.ByteArrayBuffer; import android.os.Handler; import android.os.Looper; import android.os.Message; import android.util.Log; import com.loopj.android.http.AsyncHttpClient; import com.loopj.android.http.ResponseHandlerInterface; /** * Used to intercept and handle the responses from requests made using {@link AsyncHttpClient}. The * {@link #onSuccess(int, org.apache.http.Header[], byte[])} method is designed to be anonymously * overridden with your own response handling code. <p> </p> Additionally, you can override the * {@link #onFailure(int, org.apache.http.Header[], byte[], Throwable)}, {@link #onStart()}, {@link * #onFinish()}, {@link #onRetry(int)} and {@link #onProgress(int, int)} methods as required. * <p> </p> For example: <p> </p> * <pre> * AsyncHttpClient client = new AsyncHttpClient(); * client.get("http://www.google.com", new AsyncHttpResponseHandler() { * @Override * public void onStart() { * // Initiated the request * } * * @Override * public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) { * // Successfully got a response * } * * @Override * public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable * error) * { * // Response failed :( * } * * @Override * public void onRetry() { * // Request was retried * } * * @Override * public void onProgress(int bytesWritten, int totalSize) { * // Progress notification * } * * @Override * public void onFinish() { * // Completed the request (either success or failure) * } * }); * </pre> */ public abstract class AsyncHttpResponseHandler implements ResponseHandlerInterface { private static final String LOG_TAG = "AsyncHttpResponseHandler"; protected static final int SUCCESS_MESSAGE = 0; protected static final int FAILURE_MESSAGE = 1; protected static final int START_MESSAGE = 2; protected static final int FINISH_MESSAGE = 3; protected static final int PROGRESS_MESSAGE = 4; protected static final int RETRY_MESSAGE = 5; protected static final int CANCEL_MESSAGE = 6; protected static final int BUFFER_SIZE = 4096; public static final String DEFAULT_CHARSET = "UTF-8"; private String responseCharset = DEFAULT_CHARSET; private Handler handler; private boolean useSynchronousMode; private URI requestURI = null; private Header[] requestHeaders = null; @Override public URI getRequestURI() { return this.requestURI; } @Override public Header[] getRequestHeaders() { return this.requestHeaders; } @Override public void setRequestURI(URI requestURI) { this.requestURI = requestURI; } @Override public void setRequestHeaders(Header[] requestHeaders) { this.requestHeaders = requestHeaders; } /** * Avoid leaks by using a non-anonymous handler class. */ private static class ResponderHandler extends Handler { private final AsyncHttpResponseHandler mResponder; ResponderHandler(AsyncHttpResponseHandler mResponder) { this.mResponder = mResponder; } @Override public void handleMessage(Message msg) { mResponder.handleMessage(msg); } } @Override public boolean getUseSynchronousMode() { return useSynchronousMode; } @Override public void setUseSynchronousMode(boolean value) { // A looper must be prepared before setting asynchronous mode. if (!value && Looper.myLooper() == null) { value = true; Log.w(LOG_TAG, "Current thread has not called Looper.prepare(). Forcing synchronous mode."); } // If using synchronous mode. if (!value && handler == null) { // Create a handler on current thread to submit tasks handler = new ResponderHandler(this); } else if (value && handler != null) { // TODO: Consider adding a flag to remove all queued messages. handler = null; } useSynchronousMode = value; } /** * Sets the charset for the response string. If not set, the default is UTF-8. * * @param charset to be used for the response string. * @see <a href="http://docs.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Charset</a> */ public void setCharset(final String charset) { this.responseCharset = charset; } public String getCharset() { return this.responseCharset == null ? DEFAULT_CHARSET : this.responseCharset; } /** * Creates a new AsyncHttpResponseHandler */ public AsyncHttpResponseHandler() { // Use asynchronous mode by default. setUseSynchronousMode(false); } /** * Fired when the request progress, override to handle in your own code * * @param bytesWritten offset from start of file * @param totalSize total size of file */ public void onProgress(int bytesWritten, int totalSize) { Log.v(LOG_TAG, String.format("Progress %d from %d (%2.0f%%)", bytesWritten, totalSize, (totalSize > 0) ? (bytesWritten * 1.0 / totalSize) * 100 : -1)); } /** * Fired when the request is started, override to handle in your own code */ public void onStart() { } /** * Fired in all cases when the request is finished, after both success and failure, override to * handle in your own code */ public void onFinish() { } /** * Fired when a request returns successfully, override to handle in your own code * * @param statusCode the status code of the response * @param headers return headers, if any * @param responseBody the body of the HTTP response from the server */ public abstract void onSuccess(int statusCode, Header[] headers, byte[] responseBody); /** * Fired when a request fails to complete, override to handle in your own code * * @param statusCode return HTTP status code * @param headers return headers, if any * @param responseBody the response body, if any * @param error the underlying cause of the failure */ public abstract void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error); /** * Fired when a retry occurs, override to handle in your own code * * @param retryNo number of retry */ public void onRetry(int retryNo) { Log.d(LOG_TAG, String.format("Request retry no. %d", retryNo)); } public void onCancel() { Log.d(LOG_TAG, "Request got cancelled"); } final public void sendProgressMessage(int bytesWritten, int bytesTotal) { sendMessage(obtainMessage(PROGRESS_MESSAGE, new Object[] { bytesWritten, bytesTotal })); } final public void sendSuccessMessage(int statusCode, Header[] headers, byte[] responseBytes) { sendMessage(obtainMessage(SUCCESS_MESSAGE, new Object[] { statusCode, headers, responseBytes })); } final public void sendFailureMessage(int statusCode, Header[] headers, byte[] responseBody, Throwable throwable) { sendMessage(obtainMessage(FAILURE_MESSAGE, new Object[] { statusCode, headers, responseBody, throwable })); } final public void sendStartMessage() { sendMessage(obtainMessage(START_MESSAGE, null)); } final public void sendFinishMessage() { sendMessage(obtainMessage(FINISH_MESSAGE, null)); } final public void sendRetryMessage(int retryNo) { sendMessage(obtainMessage(RETRY_MESSAGE, new Object[] { retryNo })); } final public void sendCancelMessage() { sendMessage(obtainMessage(CANCEL_MESSAGE, null)); } // Methods which emulate android's Handler and Message methods protected void handleMessage(Message message) { Object[] response; switch (message.what) { case SUCCESS_MESSAGE: response = (Object[]) message.obj; if (response != null && response.length >= 3) { onSuccess((Integer) response[0], (Header[]) response[1], (byte[]) response[2]); } else { Log.e(LOG_TAG, "SUCCESS_MESSAGE didn't got enough params"); } break; case FAILURE_MESSAGE: response = (Object[]) message.obj; if (response != null && response.length >= 4) { onFailure((Integer) response[0], (Header[]) response[1], (byte[]) response[2], (Throwable) response[3]); } else { Log.e(LOG_TAG, "FAILURE_MESSAGE didn't got enough params"); } break; case START_MESSAGE: onStart(); break; case FINISH_MESSAGE: onFinish(); break; case PROGRESS_MESSAGE: response = (Object[]) message.obj; if (response != null && response.length >= 2) { try { onProgress((Integer) response[0], (Integer) response[1]); } catch (Throwable t) { Log.e(LOG_TAG, "custom onProgress contains an error", t); } } else { Log.e(LOG_TAG, "PROGRESS_MESSAGE didn't got enough params"); } break; case RETRY_MESSAGE: response = (Object[]) message.obj; if (response != null && response.length == 1) onRetry((Integer) response[0]); else Log.e(LOG_TAG, "RETRY_MESSAGE didn't get enough params"); break; case CANCEL_MESSAGE: onCancel(); break; } } protected void sendMessage(Message msg) { if (getUseSynchronousMode() || handler == null) { handleMessage(msg); } else if (!Thread.currentThread().isInterrupted()) { // do not send messages if request has been cancelled handler.sendMessage(msg); } } /** * Helper method to send runnable into local handler loop * * @param runnable runnable instance, can be null */ protected void postRunnable(Runnable runnable) { if (runnable != null) { if (getUseSynchronousMode() || handler == null) { // This response handler is synchronous, run on current thread runnable.run(); } else { // Otherwise, run on provided handler handler.post(runnable); } } } /** * Helper method to create Message instance from handler * * @param responseMessageId constant to identify Handler message * @param responseMessageData object to be passed to message receiver * @return Message instance, should not be null */ protected Message obtainMessage(int responseMessageId, Object responseMessageData) { Message msg; if (handler == null) { msg = Message.obtain(); if (msg != null) { msg.what = responseMessageId; msg.obj = responseMessageData; } } else { msg = Message.obtain(handler, responseMessageId, responseMessageData); } return msg; } @Override public void sendResponseMessage(HttpResponse response) throws IOException { // do not process if request has been cancelled if (!Thread.currentThread().isInterrupted()) { StatusLine status = response.getStatusLine(); byte[] responseBody; responseBody = getResponseData(response.getEntity()); // additional cancellation check as getResponseData() can take non-zero time to process if (!Thread.currentThread().isInterrupted()) { if (status.getStatusCode() >= 300) { sendFailureMessage(status.getStatusCode(), response.getAllHeaders(), responseBody, new HttpResponseException(status.getStatusCode(), status.getReasonPhrase())); } else { sendSuccessMessage(status.getStatusCode(), response.getAllHeaders(), responseBody); } } } } /** * Returns byte array of response HttpEntity contents * * @param entity can be null * @return response entity body or null * @throws java.io.IOException if reading entity or creating byte array failed */ byte[] getResponseData(HttpEntity entity) throws IOException { byte[] responseBody = null; if (entity != null) { InputStream instream = entity.getContent(); if (instream != null) { long contentLength = entity.getContentLength(); if (contentLength > Integer.MAX_VALUE) { throw new IllegalArgumentException("HTTP entity too large to be buffered in memory"); } int buffersize = (contentLength <= 0) ? BUFFER_SIZE : (int) contentLength; try { ByteArrayBuffer buffer = new ByteArrayBuffer(buffersize); try { byte[] tmp = new byte[BUFFER_SIZE]; int l, count = 0; // do not send messages if request has been cancelled while ((l = instream.read(tmp)) != -1 && !Thread.currentThread().isInterrupted()) { count += l; buffer.append(tmp, 0, l); sendProgressMessage(count, (int) (contentLength <= 0 ? 1 : contentLength)); } } finally { AsyncHttpClient.silentCloseInputStream(instream); } responseBody = buffer.toByteArray(); } catch (OutOfMemoryError e) { System.gc(); throw new IOException("File too large to fit into available memory"); } } } return responseBody; } }