Question

当我想从我的应用程序将图像保存到Android时，我遇到了这个奇怪的问题。现在Android无法使用它们损坏图像。我的代码中看不到什么错误。

这是我的下载方法：

    public void createExternalStoragePublicPicture(String DownloadUrl, String fileName) {
    // Create a path where we will place our picture in the user's
    // public pictures directory.  Note that you should be careful about
    // what you place here, since the user often manages these files.  For
    // pictures and other media owned by the application, consider
    // Context.getExternalMediaDir().

    Log.i("Download", DownloadUrl);
    Log.i("File", fileName);

    File path = Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES);
    File file = new File(path, fileName);

    try {
        // Make sure the Pictures directory exists.
        path.mkdirs();

        // Very simple code to copy a picture from the application's
        // resource into the external file.  Note that this code does
        // no error checking, and assumes the picture is small (does not
        // try to copy it in chunks).  Note that if external storage is
        // not currently mounted this will silently fail.
        URL url = new URL(DownloadUrl);
        URLConnection ucon = url.openConnection();

        InputStream is = ucon.getInputStream();
        OutputStream os = new FileOutputStream(file);
        byte[] data = new byte[is.available()];
        is.read(data);
        os.write(data);
        is.close();
        os.close();

        // Tell the media scanner about the new file so that it is
        // immediately available to the user.
        MediaScannerConnection.scanFile(this,
                new String[] { file.toString() }, null,
                new MediaScannerConnection.OnScanCompletedListener() {
            public void onScanCompleted(String path, Uri uri) {
                Log.i("ExternalStorage", "Scanned " + path + ":");
                Log.i("ExternalStorage", "-> uri=" + uri);
            }
        });
    } catch (IOException e) {
        // Unable to create file, likely because external storage is
        // not currently mounted.
        Log.w("ExternalStorage", "Error writing " + file, e);
    }
}

任何想法在这里出了什么问题？

Answer 1

可能is.available()不能按预期工作。通常，您不应该依赖available()，因为它没有严格指定它返回的值。

请参阅InputStream：“特别重要的是要意识到您不能使用此方法来调整容器大小并假设您可以读取整个流[...]”）

使用常见的“循环” - 方法：

int c;
while ( (c = is.read(buf)) >= 0 ) {
  os.write(buf,0,c)
}

这确保您真正从源文件中读取所有字节。

Android文件使用getExternalStoragePublicDirectory损坏

1 个答案: