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; import java.io.IOException; 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.entity.BufferedHttpEntity; import org.apache.http.util.EntityUtils; import android.os.Handler; import android.os.Message; import android.os.Looper; /** * Used to intercept and handle the responses from requests made using * {@link AsyncHttpClient}, with automatic handling of png/jpg image data * (e.g. checks Content-Type against allowed list, Content-length). Receives response body as * byte array. * <p> * Additionally, you can override the {@link #onFailure(Throwable, String)}, * {@link #onStart()}, and {@link #onFinish()} methods as required. * <p> * For example: * <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(String response) { * // Successfully got a response * } * * @Override * public void onFailure(Throwable e, String response) { * // Response failed :( * } * * @Override * public void onFinish() { * // Completed the request (either success or failure) * } * }); * </pre> */ public class ImageHttpResponseHandler extends AsyncHttpResponseHandler { private static final int SUCCESS_MESSAGE = 0; private static final int FAILURE_MESSAGE = 1; private static final int START_MESSAGE = 2; private static final int FINISH_MESSAGE = 3; private static String[] mAllowedContentTypes = new String[] { "image/jpeg", "image/png" }; private Handler handler; /** * Creates a new AsyncHttpResponseHandler */ public ImageHttpResponseHandler() { super(); } /** * Creates a new AsyncHttpResponseHandler, and overrides the default allowed image * content types with passed String array (hopefully) of image content types. */ public ImageHttpResponseHandler(String[] allowedContentTypes) { this(); mAllowedContentTypes = allowedContentTypes; } // // Callbacks to be overridden, typically anonymously // /** * Fired when a request returns successfully, override to handle in your own code * @param content the body of the HTTP response from the server */ public void onSuccess(byte[] imageData) { } /** * Fired when a request fails to complete, override to handle in your own code * @param error the underlying cause of the failure * @deprecated use {@link #onFailure(Throwable, String)} */ public void onFailure(Throwable error) { } /** * Fired when a request fails to complete, override to handle in your own code * @param error the underlying cause of the failure * @param content the response body, if any */ public void onFailure(Throwable error, byte[] imageData) { // By default, call the deprecated onFailure(Throwable) for compatibility onFailure(error); } // // Pre-processing of messages (executes in background threadpool thread) // protected void sendSuccessMessage(byte[] responseBody) { sendMessage(obtainMessage(SUCCESS_MESSAGE, responseBody)); } protected void sendFailureMessage(Throwable e, byte[] responseBody) { sendMessage(obtainMessage(FAILURE_MESSAGE, new Object[] { e, responseBody })); } // // Pre-processing of messages (in original calling thread, typically the UI thread) // protected void handleSuccessMessage(byte[] responseBody) { onSuccess(responseBody); } protected void handleFailureMessage(Throwable e, byte[] responseBody) { onFailure(e, responseBody); } // Methods which emulate android's Handler and Message methods protected void handleMessage(Message msg) { switch (msg.what) { case SUCCESS_MESSAGE: handleSuccessMessage((byte[]) msg.obj); break; case FAILURE_MESSAGE: Object[] response = (Object[]) msg.obj; handleFailureMessage((Throwable) response[0], (byte[]) response[1]); break; case START_MESSAGE: onStart(); break; case FINISH_MESSAGE: onFinish(); break; } } // Interface to AsyncHttpRequest void sendResponseMessage(HttpResponse response) { StatusLine status = response.getStatusLine(); Header[] contentTypeHeaders = response.getHeaders("Content-Type"); byte[] responseBody = null; if (contentTypeHeaders.length != 1) { //malformed/ambiguous HTTP Header, ABORT! sendFailureMessage(new HttpResponseException(status.getStatusCode(), "None, or more than one, Content-Type Header found!"), responseBody); return; } Header contentTypeHeader = contentTypeHeaders[0]; boolean foundAllowedContentType = false; for (String anAllowedContentType : mAllowedContentTypes) { if (anAllowedContentType.equals(contentTypeHeader.getValue())) { foundAllowedContentType = true; } } if (!foundAllowedContentType) { //Content-Type not in allowed list, ABORT! sendFailureMessage(new HttpResponseException(status.getStatusCode(), "Content-Type not allowed!"), responseBody); return; } try { HttpEntity entity = null; HttpEntity temp = response.getEntity(); if (temp != null) { entity = new BufferedHttpEntity(temp); } responseBody = EntityUtils.toByteArray(entity); } catch (IOException e) { sendFailureMessage(e, (byte[]) null); } if (status.getStatusCode() >= 300) { sendFailureMessage(new HttpResponseException(status.getStatusCode(), status.getReasonPhrase()), responseBody); } else { sendSuccessMessage(responseBody); } } }