Question

我需要保存来自网络服务提供的网址的图片，然后在某些活动中我需要检索并使用该图片。

由于我已经使用Picasso下载和缓存图像，我使用了以下方法：

public void downloadFile(String url) {
        Picasso.with(AnimationActivity.this).load( url).into(new Target() {
            @Override
            public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                try {
                    String root = Environment.getExternalStorageDirectory().toString();
                    File myDir = new File(root + "/bBackground");
                    if (!myDir.exists()) {
                        myDir.mkdirs();
                    }
                    String name = "bBg.jpg";
                    myDir = new File(myDir, name);
                    FileOutputStream out = new FileOutputStream(myDir);
                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
                    out.flush();
                    out.close();                        
                    } catch(Exception e){}
            }

            @Override
            public void onBitmapFailed(Drawable errorDrawable) {}
            @Override
            public void onPrepareLoad(Drawable placeHolderDrawable) {}
        });

    }

然后为了检索我尝试使用以下代码的图像：

String bgImagePath = Environment.getExternalStorageDirectory() + "/bBackground/bBg.jpg";
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        Bitmap mustOpen = BitmapFactory.decodeFile(bgImagePath, options);

        ImageView imageView = (ImageView) findViewById(R.id.bBgImage);
        imageView.setImageBitmap(mustOpen);

但是我在检索图片时遇到错误：

E/BitmapFactory(30761): Unable to decode stream: java.io.FileNotFoundException: /storage/emulated/0/bBackground/bBg.jpg: open failed: ENOENT (No such file or directory)

我做错了什么？这是与保存或检索方法有关的问题吗？

Answer 1

您是否在清单文件中添加了以下权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

要保存图像，请使用以下功能：

public void saveBitmap(Bitmap bitmap) {

File root = android.os.Environment.getExternalStorageDirectory(); 
File dir = new File (root.getAbsolutePath() + "/bBackground");
if (!dir.exists()) {
    dir.mkdirs();
 }
File image = new File(dir, "/bBg.jpg");

try {
    FileOutputStream out = new FileOutputStream(image);
    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
    out.flush();
    out.close();    
} catch (FileNotFoundException e) {
    e.printStackTrace();
    Log.i(TAG, "******* File not found. Did you" +
            " add a WRITE_EXTERNAL_STORAGE permission to the   manifest?");
} catch (IOException e) {
    e.printStackTrace();
 }   
}

要阅读此图片，您可以使用：

public Bitmap getBitmap(){
  File root = android.os.Environment.getExternalStorageDirectory(); 
  File dir = new File (root.getAbsolutePath() + "/bBackground");
  File image = new File(dir, "/bBg.jpg");

  BitmapFactory.Options options = new BitmapFactory.Options();
  options.inPreferredConfig = Bitmap.Config.ARGB_8888;
  Bitmap mustOpen = BitmapFactory.decodeFile(image, options);

  ImageView imageView = (ImageView) findViewById(R.id.bofrostBgImage);
  imageView.setImageBitmap(mustOpen);
}

Answer 2

尝试此代码此问题与picasso目标有关。

private Target loadtarget;

    public void loadBitmap(String url) {

        if (loadtarget == null)
            loadtarget = new Target() {
                @Override
                public void onBitmapLoaded(Bitmap bitmap,
                        Picasso.LoadedFrom from) {
                    // do something with the Bitmap
                    handleLoadedBitmap(bitmap);
                }

                @Override
                public void onBitmapFailed(Drawable arg0) {
                    // TODO Auto-generated method stub

                }

                @Override
                public void onPrepareLoad(Drawable arg0) {
                    // TODO Auto-generated method stub

                }
            };

        Picasso.with(this).load(url).into(loadtarget);
    }

    public void handleLoadedBitmap(Bitmap bitmap) {
        // do something here
        try {
            String root = Environment.getExternalStorageDirectory().toString();
            File myDir = new File(root + "/bBackground");
            if (!myDir.exists()) {
                myDir.mkdirs();
            }
            String name = "bBg.jpg";
            myDir = new File(myDir, name);
            FileOutputStream out = new FileOutputStream(myDir);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 70, out);
            out.flush();
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }


        String bgImagePath = Environment.getExternalStorageDirectory()
                + "/bBackground/bBg.jpg";
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        Bitmap mustOpen = BitmapFactory.decodeFile(bgImagePath, options);

        ImageView imageView = (ImageView) findViewById(R.id.imageView1);
        imageView.setImageBitmap(mustOpen);
    }

Android从网址中保存图片，然后将其检索

2 个答案: