在 android api 23(marshmallow) 中将文件写入 sd 卡的问题

Question

当我尝试在 Api 23 中下载此文件时出现错误。它在版本

我已经像这样在 android manifest 中授予了读写权限。

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

下载.java

import java.io.File;

import android.app.Activity;
import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Toast;


public class Download extends Activity {
  private DownloadManager mgr=null;
  private long lastDownload=-1L;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_download);

    mgr=(DownloadManager)getSystemService(DOWNLOAD_SERVICE);
    registerReceiver(onComplete,
                     new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
    registerReceiver(onNotificationClick,
                     new IntentFilter(DownloadManager.ACTION_NOTIFICATION_CLICKED));


  }

  @Override
  public void onDestroy() {
    super.onDestroy();

    unregisterReceiver(onComplete);
    unregisterReceiver(onNotificationClick);
  }

  public void startDownload(View v) {
    Uri uri=Uri.parse("http://oursite/pictures/image.jpg");


    Environment
      .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
      .mkdirs();

    lastDownload=
      mgr.enqueue(new DownloadManager.Request(uri)
                  .setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI |
                                          DownloadManager.Request.NETWORK_MOBILE)
                  .setAllowedOverRoaming(false)
                  .setTitle("Pictures")
                  //.setDescription("Something useful. No, really.")
                  .setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS,
                                                     "aadhar.jpg"));

    v.setEnabled(false);
    //findViewById(R.id.query).setEnabled(true);

  }

  public void queryStatus(View v) {
    Cursor c=mgr.query(new DownloadManager.Query().setFilterById(lastDownload));

    if (c==null) {
      Toast.makeText(this, "Update not found!", Toast.LENGTH_LONG).show();
    }
    else {
      c.moveToFirst();

      Log.d(getClass().getName(), "COLUMN_ID: "+
            c.getLong(c.getColumnIndex(DownloadManager.COLUMN_ID)));
      Log.d(getClass().getName(), "COLUMN_BYTES_DOWNLOADED_SO_FAR: "+
            c.getLong(c.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR)));
      Log.d(getClass().getName(), "COLUMN_LAST_MODIFIED_TIMESTAMP: "+
            c.getLong(c.getColumnIndex(DownloadManager.COLUMN_LAST_MODIFIED_TIMESTAMP)));
      Log.d(getClass().getName(), "COLUMN_LOCAL_URI: "+
            c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI)));
      Log.d(getClass().getName(), "COLUMN_STATUS: "+
            c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS)));
      Log.d(getClass().getName(), "COLUMN_REASON: "+
            c.getInt(c.getColumnIndex(DownloadManager.COLUMN_REASON)));

      Toast.makeText(this, statusMessage(c), Toast.LENGTH_LONG).show();
    }
  }

  public void viewLog(View v) {
    startActivity(new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS));
  }

  private String statusMessage(Cursor c) {
    String msg="???";

    switch(c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS))) {
      case DownloadManager.STATUS_FAILED:
        msg="Update failed!";
        break;

      case DownloadManager.STATUS_PAUSED:
        msg="Update paused!";
        break;

      case DownloadManager.STATUS_PENDING:
        msg="Update pending!";
        break;

      case DownloadManager.STATUS_RUNNING:
        msg="Update in progress!";
        break;

      case DownloadManager.STATUS_SUCCESSFUL:
        msg="Update complete!";
        break;

      default:
        msg="Update software is nowhere in sight";
        break;
    }

    return(msg);
  }

  BroadcastReceiver onComplete=new BroadcastReceiver() {
    public void onReceive(Context ctxt, Intent intent) {
      findViewById(R.id.start).setEnabled(true);
    }
  };

  BroadcastReceiver onNotificationClick=new BroadcastReceiver() {
    public void onReceive(Context ctxt, Intent intent) {
      Toast.makeText(ctxt, "Ummmm...hi!", Toast.LENGTH_LONG).show();
    }
  };
}

Answer 1

请检查以下解决方案，希望它对您正常工作。

 public void startDownload(View v) 
 {
    int result = ContextCompat.checkSelfPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE);
   if (result == PackageManager.PERMISSION_GRANTED){

       startDownloading();

   } else {

       requestForLocationPermission(); 
   }
 }


   private void requestForLocationPermission()
   {

      if (ActivityCompat.shouldShowRequestPermissionRationale(activity,Manifest.permission.WRITE_EXTERNAL_STORAGE))
      {
      } 
      else {

          ActivityCompat.requestPermissions(activity,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},PERMISSION_REQUEST_CODE);
      }
   }

  @Override
  public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) 
  {
      switch (requestCode) {
       case PERMISSION_REQUEST_CODE:
           if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) 
        { 
           startDownloading();
        } 
        break;
  }
}


  public void startDownloading()
  {
      Uri uri=Uri.parse("http://oursite/pictures/image.jpg");


      Environment
  .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
  .mkdirs();

      lastDownload = mgr.enqueue(new DownloadManager.Request(uri)
              .setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI |
                                      DownloadManager.Request.NETWORK_MOBILE)
              .setAllowedOverRoaming(false)
              .setTitle("Pictures")
              //.setDescription("Something useful. No, really.")
              .setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS,
                                                 "aadhar.jpg"));

      v.setEnabled(false);
      //findViewById(R.id.query).setEnabled(true);
    }

Answer 2

试试下面的代码

private void showPermissionDialog() {
    // Here, thisActivity is the current activity
    if (ContextCompat.checkSelfPermission(mActivity,
            Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {

        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(mActivity,
                Manifest.permission.WRITE_EXTERNAL_STORAGE)) {

            // Show an expanation to the user *asynchronously* -- don't block
            // this thread waiting for the user's response! After the user
            // sees the explanation, try again to request the permission.

        } else {

            // No explanation needed, we can request the permission.

            ActivityCompat.requestPermissions(mActivity,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                    MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);

            // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
    } else {
        showTakeImagePopup();
    }
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                showTakeImagePopup();
                // permission was granted, yay! Do the
                // contacts-related task you need to do.

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

也声明这个

 private static final int MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE = 1;

Answer 3

首先，我检查我是否有权限：

private static final int REQUEST_WRITE_STORAGE = 112;

boolean hasPermission = (ContextCompat.checkSelfPermission(activity,
            Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED);
if (!hasPermission) {
    ActivityCompat.requestPermissions(parentActivity,
                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                REQUEST_WRITE_STORAGE);
}

然后检查用户是否认可：

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    switch (requestCode)
    {
        case REQUEST_WRITE_STORAGE: {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
            {
                //reload my activity with permission granted or use the features what required the permission
            } else
            {
                Toast.makeText(parentActivity, "The app was not allowed to write to your storage. Hence, it cannot function properly. Please consider granting it this permission", Toast.LENGTH_LONG).show();
            }
        }
    }

}

Refer Link