Java tutorial
/* * Copyright (C) 2011 Google Inc. * * 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.partytv.server; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.http.AndroidHttpClient; import android.os.AsyncTask; import org.apache.http.Header; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.methods.HttpGet; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.MalformedURLException; import java.net.URL; /** * Utilities for loading a bitmap from a URL. All network transactions and * image scaling is done on non-UI thread using AsyncTask. */ public class BitmapUtilsTask extends AsyncTask<Object, Void, Bitmap> { private static final String TAG = "Panoramio"; /** * Loads a bitmap from the specified url. * * @param url The location of the bitmap asset * @return The bitmap, or null if it could not be loaded * @throws IOException * @throws MalformedURLException */ public Bitmap getBitmap(final String string, Object fileObj) throws MalformedURLException, IOException { File file = (File) fileObj; // Get the source image's dimensions int desiredWidth = 1000; BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; if (!file.isFile()) { InputStream is = (InputStream) new URL(string).getContent(); BitmapFactory.decodeStream(is, null, options); is.close(); } else { BitmapFactory.decodeFile(file.getAbsolutePath(), options); } int srcWidth = options.outWidth; int srcHeight = options.outHeight; // Only scale if the source is big enough. This code is just trying // to fit a image into a certain width. if (desiredWidth > srcWidth) desiredWidth = srcWidth; // Calculate the correct inSampleSize/scale value. This helps reduce // memory use. It should be a power of 2 int inSampleSize = 1; while (srcWidth / 2 > desiredWidth) { srcWidth /= 2; srcHeight /= 2; inSampleSize *= 2; } // Decode with inSampleSize options.inJustDecodeBounds = false; options.inDither = false; options.inSampleSize = inSampleSize; options.inScaled = false; options.inPreferredConfig = Bitmap.Config.ARGB_8888; options.inPurgeable = true; Bitmap sampledSrcBitmap; if (!file.isFile()) { InputStream is = (InputStream) new URL(string).getContent(); sampledSrcBitmap = BitmapFactory.decodeStream(is, null, options); is.close(); } else { sampledSrcBitmap = BitmapFactory.decodeFile(file.getAbsolutePath(), options); } return sampledSrcBitmap; } private void loadBitmap(String url, Object fileObj) { File file = (File) fileObj; final AndroidHttpClient client = AndroidHttpClient.newInstance("Android"); final HttpGet request = new HttpGet(url); try { HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if (statusCode != HttpStatus.SC_OK) { Header[] headers = response.getHeaders("Location"); if (headers != null && headers.length != 0) { String newUrl = headers[headers.length - 1].getValue(); // call again with new URL loadBitmap(newUrl, file); return; } } final HttpEntity entity = response.getEntity(); if (entity != null) { InputStream inputStream = null; FileOutputStream out = new FileOutputStream(file); try { inputStream = entity.getContent(); byte buf[] = new byte[16384]; do { int numread = inputStream.read(buf); if (numread <= 0) break; out.write(buf, 0, numread); } while (true); } finally { if (inputStream != null) { inputStream.close(); out.close(); } entity.consumeContent(); } } } catch (Exception e) { request.abort(); } finally { if (client != null) { client.close(); } } } /** * Loads a bitmap from the specified url. * * @param url The location of the bitmap asset * @return The bitmap, or null if it could not be loaded */ public Bitmap loadThumbnail(String string) { Bitmap bitmap = null; InputStream is; try { is = (InputStream) new URL(string).getContent(); BitmapFactory.Options optsDownSample = new BitmapFactory.Options(); bitmap = BitmapFactory.decodeStream(is, null, optsDownSample); } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return bitmap; } /** * The system calls this to perform work in a worker thread and delivers * it the parameters given to AsyncTask.execute() */ @Override protected Bitmap doInBackground(Object... item) { try { if (item[1].toString().equals("thumb")) return loadThumbnail(item[0].toString()); else if (item[1].toString().equals("load")) { loadBitmap(item[0].toString(), item[2]); return null; } else return getBitmap(item[0].toString(), item[2]); } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return null; } }