使用 getFileDescriptor 加载图像的子采样版本时 EBADF（错误文件编号）

Question

我试图在单个后台线程中使用 AsyncTask 执行以下代码。它给出 错误文件编号 .
在 google 上搜索后，我发现不止一个线程尝试同时访问或打开以下文件，但在我的场景中，只有一个后台线程运行使用 asynctask 。下面的 decodeBitmapFromDescriptor 方法在 SinglTone Class.

中定义

public Bitmap decodeBitmapFromDescriptor(Uri data, int reqWidth, int reqHeight) throws FileNotFoundException {

        FileDescriptor fileDescriptor= mContext.getContentResolver().
                        openFileDescriptor(data, "r").getFileDescriptor();

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;

        BitmapFactory.decodeFileDescriptor(fileDescriptor, null, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        Bitmap bmp=BitmapFactory.decodeFileDescriptor(fileDescriptor, null, options);

        // it returns null don't know why ?? it works on api level 21
        if(bmp==null){
            bmp=BitmapFactory.decodeFileDescriptor(fileDescriptor);
        }
        return bmp;
    }

以下是错误的堆栈跟踪。

java.io.IOException: read failed: EBADF (Bad file number) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at libcore.io.IoBridge.read(IoBridge.java:442) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at java.io.FileInputStream.read(FileInputStream.java:179) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at java.io.BufferedInputStream.fillbuf(BufferedInputStream.java:168) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at java.io.BufferedInputStream.read(BufferedInputStream.java:309) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at android.graphics.BitmapFactory.nativeDecodeStream(Native Method) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:527) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at android.graphics.BitmapFactory.decodeFileDescriptor(BitmapFactory.java:626) 05-13 11:16:04.652 17881-19663/com.espec.bosleo.espec W/System.err﹕ at android.graphics.BitmapFactory.decodeFileDescriptor(BitmapFactory.java:644) ..................................

注意：以上代码在 Lollipop 版本 API21 上正常工作

Answer 1

我刚刚完成了它。忘记关闭 ParcelFileDescriptor。

public Bitmap decodeBitmapFromDescriptor(Uri data,
                                         int reqWidth, int reqHeight) throws IOException {

        ParcelFileDescriptor ParcelFileDescriptor= mContext.getContentResolver().
                        openFileDescriptor(data, "r");
        FileDescriptor fileDescriptor=ParcelFileDescriptor.getFileDescriptor();

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;

        BitmapFactory.decodeFileDescriptor(fileDescriptor, null, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        Bitmap bmp=BitmapFactory.decodeFileDescriptor(fileDescriptor, null, options);
        // Here is the solution of my problem
        ParcelFileDescriptor.close();
        fileDescriptor=null;
//        if(bmp==null){
//            bmp=BitmapFactory.decodeFileDescriptor(fileDescriptor);
//        }
        return bmp;
    }

使用 getFileDescriptor 加载图像的子采样版本时 EBADF（错误文件编号）

EBADF (Bad file number) while loading subsampled version of image using getFileDescriptor

multithreading

android

file-descriptor

android-contentprovider

android-asynctask