今天寫一下儲存圖片到手機相簿的功能！

整個儲存圖片的程式碼如下：

public void saveImageToGallery(Context context, Bitmap bmp) {
        if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            return;
        }
        // 首先儲存圖片
        File appDir = Environment.getExternalStoragePublicDirectory
 
(Environment.DIRECTORY_DCIM).getAbsoluteFile();
        if (!appDir.exists()) {
            appDir.mkdir();
        }
        String fileName = System.currentTimeMillis() + ".png";
        File file = new File(appDir, fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
 

            bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            return;
        } catch (IOException e) {
            e.printStackTrace();
            return;
        }
        try {
            MediaStore.Images
 
.Media.insertImage(context.getContentResolver(),
                    file.getAbsolutePath(), fileName, null);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // 最後通知相簿更新
        context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + file.getAbsolutePath())));
    }

長按圖片的事件

 imgView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                saveImageToGallery(MainActivity.this, bitmap);
                return true;//true代表消費了該事件，不在往下傳遞，如果返回false，會觸發onclicklistener時間
            }
        });

特別注意這點：呼叫getDrawingCache()前先要測量，否則的話得到的bitmap為null,也就是儲存到相簿裡圖片會變黑的問題

  imgView = findViewById(R.id.icon);
  imgView.setDrawingCacheEnabled(true);
        imgView.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
        imgView.layout(0, 0, imgView.getMeasuredWidth(), imgView.getMeasuredHeight());
        bitmap = Bitmap.createBitmap(imgView.getDrawingCache());
        imgView.setDrawingCacheEnabled(false);