Android开发实现保存图片到手机相册功能

String[] PERMISSIONS = {
    "android.permission.READ_EXTERNAL_STORAGE",
    "android.permission.WRITE_EXTERNAL_STORAGE" };
//检测是否有写的权限
int permission = ContextCompat.checkSelfPermission(this,
    "android.permission.WRITE_EXTERNAL_STORAGE");
if (permission != PackageManager.PERMISSION_GRANTED) {
  // 没有写的权限，去申请写的权限，会弹出对话框
  ActivityCompat.requestPermissions(this, PERMISSIONS,1);
}
保存文件的方法：
public void SaveBitmapFromView(View view) {
  int w = view.getWidth();
  int h = view.getHeight();
  Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
  Canvas c = new Canvas(bmp);
  view.layout(0, 0, w, h);
  view.draw(c);
 // 缩小图片
 Matrix matrix = new Matrix();
 matrix.postScale(0.5f,0.5f); //长和宽放大缩小的比例
 bmp = Bitmap.createBitmap(bmp,0,0,        bmp.getWidth(),bmp.getHeight(),matrix,true);
 DateFormat format = new SimpleDateFormat("yyyyMMddHHmmss"); 
  saveBitmap(bmp,format.format(new Date())+".JPEG");
}
/*
 * 保存文件，文件名为当前日期
 */
Public void saveBitmap(Bitmap bitmap, String bitName){
    String fileName ;
    File file ;
    if(Build.BRAND .equals("Xiaomi") ){ // 小米手机 
      fileName = Environment.getExternalStorageDirectory().getPath()+"/DCIM/Camera/"+bitName ;
    }else{ // Meizu 、Oppo
      fileName = Environment.getExternalStorageDirectory().getPath()+"/DCIM/"+bitName ;
    }
    file = new File(fileName);
    if(file.exists()){
      file.delete();
    }
    FileOutputStream out;
    try{
      out = new FileOutputStream(file);
 // 格式为 JPEG，照相机拍出的图片为JPEG格式的，PNG格式的不能显示在相册中
      if(bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out))
      {
        out.flush();
        out.close();
// 插入图库  
         MediaStore.Images.Media.insertImage(this.getContentResolver(), file.getAbsolutePath(), bitName, null);
      }
    }
    catch (FileNotFoundException e)
    {
      e.printStackTrace();
    }
    catch (IOException e)
    {
      e.printStackTrace();
    }
 // 发送广播，通知刷新图库的显示
    this.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + fileName)));
}