Android 使用Picasso加载网络图片等比例缩放

转自：http://blog.csdn.net/picasso_l/article/details/50679177最近做项目，要下载图片到本地（不是指缓存），之前用过HttpURLConnection和HttpCLient，但是感觉太繁琐，而且6.0之后到Apache包也不支持了，后来我想到了Picasso的缓存，Picasso缓存图片，那肯定是下载到本地实现了，我们只要更改下本地路径，就能轻松实现了。废话不多说，直接上代码了。private void download() {//获得图片的地址String url = mList.get(mPosition);//TargetTarget target = new Target(){@Overridepublic void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {String imageName = System.currentTimeMillis() + ".png";File dcimFile = FileUtil.getDCIMFile(FileUtil.PATH_PHOTOGRAPH,imageName);LogCat.i("bitmap="+bitmap);FileOutputStream ostream = null;try {ostream = new FileOutputStream(dcimFile);bitmap.compress(Bitmap.CompressFormat.PNG, 100, ostream);ostream.close();} catch (Exception e) {e.printStackTrace();}Toast.makeText(PicActivity.this,"图片下载至:"+dcimFile,Toast.LENGTH_SHORT).show();}@Overridepublic void onBitmapFailed(Drawable errorDrawable) {}@Overridepublic void onPrepareLoad(Drawable placeHolderDrawable) {}};//Picasso下载Picasso.with(this).load(url).into(target);}应网友要求，贴出FileUtil代码：

public class FileUtil {/*** 拍照路径*/private static String FILE_NAME = "userIcon.jpg";public static String PATH_PHOTOGRAPH = "/LXT/";private static boolean isExternalStorageWritable() {String state = Environment.getExternalStorageState();return Environment.MEDIA_MOUNTED.equals(state);}public static File getAvailableCacheDir() {if (isExternalStorageWritable()) {return App.app.getExternalCacheDir();} else {return App.app.getCacheDir();}}public static String getAvatarCropPath() {return new File(getAvailableCacheDir(), FILE_NAME).getAbsolutePath();}public static String getPublishPath(String fileName) {return new File(getAvailableCacheDir(), fileName).getAbsolutePath();}/*** 保存图片** @param bitmap* @param filePath*/public static void saveBitmap(Bitmap bitmap, String filePath) {FileOutputStream bos = null;File file = new File(filePath);if (!file.getParentFile().exists()) {file.getParentFile().mkdirs();}try {bos = new FileOutputStream(file);bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);} catch (FileNotFoundException e) {e.printStackTrace();} finally {try {bos.flush();bos.close();} catch (IOException e) {e.printStackTrace();}}}public static void deleteDir(File directory) {if (directory != null){if (directory.isFile()) {directory.delete();return;}if (directory.isDirectory()) {File[] childFiles = directory.listFiles();if (childFiles == null || childFiles.length == 0) {directory.delete();return;}for (int i = 0; i < childFiles.length; i++) {deleteDir(childFiles[i]);}directory.delete();}}}public static File getDCIMFile(String filePath, String imageName) {if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { // 文件可用File dirs = new File(Environment.getExternalStorageDirectory(),"DCIM"+filePath);if (!dirs.exists())dirs.mkdirs();File file = new File(Environment.getExternalStorageDirectory(),"DCIM"+filePath+imageName);if (!file.exists()) {try {//在指定的文件夹中创建文件file.createNewFile();} catch (Exception e) {}}return file;} else {return null;}}public static File saveBitmap2(Bitmap bitmap, String fileName, File baseFile) {FileOutputStream bos = null;File imgFile = new File(baseFile, "/" + fileName);try {bos = new FileOutputStream(imgFile);bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);} catch (FileNotFoundException e) {e.printStackTrace();} finally {try {bos.flush();bos.close();} catch (IOException e) {e.printStackTrace();}}return imgFile;}public static File getBaseFile(String filePath) {if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { // 文件可用File f = new File(Environment.getExternalStorageDirectory(),filePath);if (!f.exists())f.mkdirs();return f;} else {return null;}}public static String getFileName() {String fileName = FILE_NAME ;return fileName;}/*** 由指定的路径和文件名创建文件*/public static File createFile(String path, String name) throws IOException {File folder = new File(path);if (!folder.exists()) {folder.mkdirs();}File file = new File(path + name);if (!file.exists()) {file.createNewFile();}return file;}}

这样就轻松实现了，值得注意的是，我们经常用的是into（ImageView target），其实into还能传入很多不同的对象。今天有点晚了，先写到这，关于Picasso，还是有很多技巧可以探索的。之前还写过一篇Android 使用Picasso加载网络图片等比例缩放的文章，也欢迎大家有空去指点一下。参考文献：http://stackoverflow.com/questions/27729976/download-and-save-images-using-picasso