android - 写入文件到 SD_Card

Question

///已编辑

我尝试在主线程上运行程序，它可以读取和保存。

我认为是异步任务的问题!!

///

首先我已经将用户权限添加到android list

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

我尝试从mnt/sdcard/Bluetooth读取原始图像数据并处理，然后写入内部sdcard，写入路径为mnt/sdcard/Bluetooth.

程序可以在我的android模拟器中运行并保存文件。

但是在真机上运行，​​手机好像只能读取我的文件，不能保存文件。

    public class MainActivity extends Activity {
String filenameIn ="ardrone.raw"; 
File file = new File(Environment.getExternalStorageDirectory()+"/Bluetooth/",            filenameIn);
String filename ="convertA.jpg"; 
File outputfile = new File(Environment.getExternalStorageDirectory() +"/Bluetooth/",filename);
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myImageView = (ImageView)findViewById(R.id.imageView);
    Toast.makeText(this, "search raw file", Toast.LENGTH_LONG).show();
    new imageProcess().execute(); 
     sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,Uri.parse("file://" + Environment.getExternalStorageDirectory())));        
     Bitmap myBitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()
             .getAbsolutePath()+"/Bluetooth/convertA.jpg");
     myImageView.setImageBitmap(myBitmap);

    if (file.exists()){
         Toast.makeText(this, "InFile:)", Toast.LENGTH_LONG).show();
    }
    else{
         Toast.makeText(this, "InFile:(((((", Toast.LENGTH_LONG).show();
    }
    if (outputfile.exists()){
         Toast.makeText(this, "outputfile:)", Toast.LENGTH_LONG).show();
    }
    else{
         Toast.makeText(this, "outputfile:(((((", Toast.LENGTH_LONG).show();
    }

}

public class imageProcess extends AsyncTask<String, Integer, Boolean>{
    Boolean check_point= false;
    @Override
    protected Boolean doInBackground(String... arg0) {

        try {
                receiveVideoRawData();

        } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
        }

            return null;
      }  


}   




public void receiveVideoRawData() throws IOException{
    byte[] buf_rcv = new byte[153600];
    ByteArrayOutputStream ous = new ByteArrayOutputStream();
    InputStream ios = new FileInputStream(file);
    int read = 0;
     while ( (read = ios.read(buf_rcv)) != -1 ) {
               ous.write(buf_rcv, 0, read);
            }
                ous.close();
                ios.close();

        ReadRawFileImage readMyRawData=new ReadRawFileImage();      
        image = readMyRawData.readUINT_RGBImage(buf_rcv);
                    //transfer data
        OutputStream _outStream  = new FileOutputStream(outputfile);
         Bitmap pBitmap = image ;
         pBitmap.compress(Bitmap.CompressFormat.JPEG, 90, _outStream); 
          _outStream.flush();
          _outStream.close();





}
}

Answer 1

首先是检查你的路径是否存在；在不同的手机上，SD 卡可能安装在不同的位置。在我的 Linux 上，

$ ~/android-sdk-linux/platform-tools/adb shell ls -l /mnt/sdcard/

第二件事是检查文件和包含目录的权限。

然后，您可能会检查日志(它们可能已经包含一条错误消息)；然后，将调试输出添加到您的代码并使用该调试输出检查日志。