java - FileNotFoundException 从 SD 卡路径加载图像

Question

我试图通过打开一个文件从 SD 卡/设备内存加载图像，并以表示路径的字符串作为参数:

File imagePathFile = new File(savedImapthPathwayOnPause);
        try {

            final int IMAGE_MAX_SIZE = 3000;
            FileInputStream streamIn = new FileInputStream(imagePathFile);

            // important to reduce size of image before it is loaded into memory
            // and then resized, otherwise will
            // get out of memory error

            // Decode image size and setInJBounds = true to avoid auto memory
            // allocation for large image
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(streamIn, null, o);
            streamIn.close();

            //by setting m.pow(scale, 3.85) we get a org image of 2500:1400 beofre loaded and when loaded we get 426:240, no need fro resize method call here
            int scale = 1;
            while ((o.outWidth * o.outHeight) * (1 / Math.pow(scale, 3.73)) > IMAGE_MAX_SIZE) {
                scale++;
            }

            // get orginal width of image before loaded into memory
            Log.d("VIEW DIVE", "scale = " + scale + ", orig-width: " + o.outWidth
                    + "  orig-height: " + o.outHeight);
            //Toast.makeText(getApplicationContext(), "Orginal Image size from DB: width: "+ o.outWidth + "/height: " + o.outHeight , Toast.LENGTH_LONG).show();

            Bitmap b = null;
            streamIn = new FileInputStream(imagePathFile);
            if (scale > 1) {
                scale--;
                // scale to max possible inSampleSize that still yields an image
                // larger than target, inSampleSize loads the image into memor
                // by a factor of its integer value
                o = new BitmapFactory.Options();
                o.inSampleSize = scale;
                // Decode bitmap with inSampleSize set
                o.inJustDecodeBounds = false;

                b = BitmapFactory.decodeStream(streamIn, null, o);
                //makeToast("Image after sacling and now loading: width: "+ o.outWidth + "/height: " + o.outHeight );
                //resizedImage = reSizeImage(b); this is blowing uo and alreadt samll image from
                //org size 2500:1400 to 73:44, then blown back up in resize does not look good

                streamIn.close();
                //b.recycle();
                System.gc();

但我不断收到以下异常:

java.io.FileNotFoundException: /: open failed: EISDIR (Is a directory)
    at libcore.io.IoBridge.open(IoBridge.java:416)  at
java.io.FileInputStream.<init>(FileInputStream.java:78)     at
com.mooney.diveapp.LogDive.setImageViewFromSavedInstance(LogDive.java:198)
    at com.mooney.diveapp.LogDive.onCreate(LogDive.java:134)    at
android.app.Activity.performCreate(Activity.java:5255)      at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)

编辑:如何设置请求的图像路径字符串(在 asycnh 内部类中完成):

// check if external storage is available to write
            Bitmap imageToSave = params[0];// get image

            final String state = Environment.getExternalStorageState();
            if (Environment.MEDIA_MOUNTED.equals(state)) {
                // media available
                canSaveToExternalSD = true;
                // use a random number to append to image file name until use
                // diveNumber according to log entry on
                Random diveNum = new Random();
                File sdCard = Environment.getExternalStorageDirectory();
                final File directory = new File(sdCard.getAbsolutePath()
                        + File.separator + diveAlbum);
                final File theFile = new File(directory, "image"
                        + diveNum.nextInt(5000) + ".png");
                directory.getParentFile().mkdirs();

                if (!directory.mkdirs()) {
                    Log.d(TAG, "Directory not created!!!!");
                }

                try {
                    FileOutputStream out = new FileOutputStream(theFile);
                    imageToSave.compress(Bitmap.CompressFormat.PNG, 90, out);
                    out.flush();
                    out.close();

//assign path to a string
savedImagePath = theFile.getAbsolutePath();

稍后在代码中，saveImagePath 被分配给savedImapthPathwayOnPause。

编辑:稍后在代码中扩展。因此，当用户通过从 Activity B 中调用 Goggle Maps 或 Facebookpost Activity 来导航离开表单 Activity A 时，我将字符串 savingImagePath 保存在 onSavedINStance 状态中。

然后，当用户返回 Activity A 时，我会在创建时重新获取 savingIMagePathway，并将其传递给上面发布的 File imagePathFile = new File(savedImagePathwayOnPause) 上面发布的方法。

此时savedImagePathwayOnPause的值为:/storage/emulated/0/dive_photos/image2588.png

但是，有时此值返回空(为其初始化状态=“”)。这似乎是随机的......因为有些时候有效，而另一些则无效......

@Override
        protected void onSaveInstanceState(Bundle outState) {

            //if onPause called on activity when user selects maps or FB, we lose value of global varibles like 
            //saveIMageBPath and photoBitMap but keep all view values (Edittexts)
            //so we must save our global values here and call them back on onRestoreInstance state and assign to IMageButton

            super.onSaveInstanceState(outState);
            uiHelper.onSaveInstanceState(outState);


           outState.putString("savedImapthPathwayOnSaveInstance", savedImagePath);
        }

在 onCreate() 中:

if (savedInstanceState != null) {
            // Restore value of members from saved state
           // mCurrentScore = savedInstanceState.getInt(STATE_SCORE); 
            this.savedImapthPathwayOnPause = savedInstanceState.getString("savedImapthPathwayOnSaveInstance");
            Toast.makeText(getApplicationContext(), "on returning the image path is : " + savedImapthPathwayOnPause, Toast.LENGTH_SHORT).show();
            //no we ust get the bitmap form the image path and return to IMageView
            Log.d("MYTAG", "on returning the image path is : " + savedImapthPathwayOnPause);

            if(!savedImapthPathwayOnPause.isEmpty())
            setImageViewFromSavedInstance(savedImapthPathwayOnPause);
            Log.d("MYTAG", "on returning the image path not found:==  " + savedImapthPathwayOnPause);
        }

Answer 1

正如 @Paf 所建议的，问题是图像路径是在同步类中生成的，因此如果在生成路径之前调用 File open，我会将空字符串传递给 File 构造函数。

为了避免这种情况，我通过禁用在 Pre-Exceute 中执行此操作的按钮来禁用对创建文件的任何调用，并在生成字符串文件路径后在 Aynsch 内部类的 onPostExceute 方法中再次启用它们。

谢谢