在后台android执行do时出错[重复]

Question

我有两件事想问。我已经准备好在这个阶段吃掉这台笔记本电脑了。 我的位置权限似乎正在工作，因为我没有发生崩溃或对话说我没有权限，（尽管我也没有看到请求权限的对话......）但是 setText() 到textView 似乎也没有做这项工作。我的最新问题是在拍摄照片后检索图像以进行图像上传编码。

这是我的代码。在清单中请求权限。如果我要花更长的时间看这台笔记本电脑，我会用靴子开着这台笔记本电脑穿过花园。坚持了 3 天，一个项目两周后到期，还剩下一个月的工作量。救救我 stackoverflow！

package com.example.gary.natureallv2;

import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.location.Location;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Environment;
import android.os.Parcelable;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Base64;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import android.Manifest;


import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.FusedLocationProviderApi;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class CameraPicActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener {

    public static final int CAMERA_REQUEST = 10;
    public static final int IMAGE_GALLERY_REQUEST = 20;
    private ImageView ivPicSelected;
    private FusedLocationProviderApi locationProviderApi = LocationServices.FusedLocationApi;
    private GoogleApiClient googleApiClient;
    private LocationRequest locationRequest;
    public final static int MILLISECONDS_PER_SECOND = 1000;
    public final static int MINUTE = 60 * MILLISECONDS_PER_SECOND;
    private static final int MY_PERMISSION_REQUEST_FINE_LOCATION = 101;
    private static final int MY_PERMISSION_REQUEST_COARSE_LOCATION = 102;
    private boolean permissionIsGranted = false;
    private TextView tvLatValue;
    private TextView tvLongValue;
    private double longitude;
    private double latitude;
    private String encoded_string, image_name;
    private Bitmap bitmap;
    private  File file;
    private Uri file_uri;
    private Button btnUploadPic;
    private Parcelable picUri;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera_pic);

        googleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();
        //initialise the location request with the accuracy and frequency with which we want location updates
        locationRequest = new LocationRequest();
        locationRequest.setInterval(MINUTE);
        locationRequest.setFastestInterval(15 * MILLISECONDS_PER_SECOND);
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        ivPicSelected = (ImageView) findViewById(R.id.ivPicSelected);
        tvLatValue = (TextView) findViewById(R.id.tvLatValue);
        tvLongValue = (TextView) findViewById(R.id.tvLongValue);
        btnUploadPic = (Button) findViewById(R.id.btnUploadPic);
        btnUploadPic.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                getFileUri();
            }
        });
    }




    /**
     * Method called when btnFromCamera is clicked.
     * @param view
     */
    public void btnFromCameraClicked(View view){
        Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        File pictureDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);//
//        String pictureName = getPictureName();//
//        File imageFile = new File(pictureDirectory, pictureName);//
//        Uri pictureUri = Uri.fromFile(imageFile);//
//        cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT,pictureUri);//
        startActivityForResult(cameraIntent, CAMERA_REQUEST);

    }

    /**
     * This method is invoked when the user presses the From Gallery button.
     * @param view
     */
    public void onBtnGalleryClicked(View view){
        //Invoke the image gallery with an implicit intent.
        Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
        //Where to find the data.
        File pictureDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        String pictureDirectoryPath = pictureDirectory.getPath();
        //get a Uri representation.
        Uri data = Uri.parse(pictureDirectoryPath);
        //set the data and type/get all image types.
        photoPickerIntent.setDataAndType(data, "image/*");
        startActivityForResult(photoPickerIntent, IMAGE_GALLERY_REQUEST);


    }

    private String getPictureName() {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss");
        String timeStamp = sdf.format(new Date());
        return "natureall" + timeStamp +".jpg";
    }

    private void getFileUri() {
        image_name = "testing123.jpg";
        file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES)
                + File.separator + image_name);
        file_uri = Uri.fromFile(file);



    }

    public void onBtnUploadClick(View view){
        Intent i = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        getFileUri();
        i.putExtra(MediaStore.EXTRA_OUTPUT, file_uri);
        startActivityForResult(i, 10);

    }





    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == RESULT_OK){
            if (requestCode == CAMERA_REQUEST){
                Bitmap cameraImage = (Bitmap) data.getExtras().get("data");
                ivPicSelected.setImageBitmap(cameraImage);


            }
            if (requestCode == IMAGE_GALLERY_REQUEST){
                Uri imageUri = data.getData();
                //declare a stream to read the image data.
                InputStream inputStream;
                try {
                    inputStream = getContentResolver().openInputStream(imageUri);

                    Bitmap image = BitmapFactory.decodeStream(inputStream);
                    ivPicSelected.setImageBitmap(image);
                } catch (FileNotFoundException e) {
                    Toast.makeText(this, "Unable to open the image",Toast.LENGTH_LONG ).show();
                }

            }
            if(requestCode == 10 && resultCode == RESULT_OK) {
                new Encode_image().execute();
            }
        }
    }
/*Possible way to recover pics after saving to external storage*/
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);


        outState.putParcelable("picUri", picUri);
    }

    @Override
    protected void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);

        picUri= savedInstanceState.getParcelable("picUri");

    }
    /*End of/Possible way to recover pics after saving to external storage*/

    private class Encode_image extends AsyncTask<Void, Void, Void> {
        @Override
        protected Void doInBackground(Void... voids) {
            bitmap = BitmapFactory.decodeFile(file_uri.getPath());
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);

            byte [] array = stream.toByteArray();
            encoded_string = Base64.encodeToString(array, 0);
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            makeRequest();
        }
    }

    private void makeRequest() {
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        StringRequest request = new StringRequest(Request.Method.POST, "http://192.168.1.15/myDocs/mainProject/res/connection.php",
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {

                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        }){
            @Override
            protected Map<String, String> getParams ()throws AuthFailureError {
                HashMap<String, String> map = new HashMap<>();
                map.put("encoded_string", encoded_string);
                map.put("image_name", image_name);
                return map;
            }

        };
        requestQueue.add(request);
    }



    @Override
    public void onConnected(Bundle bundle){requestLocationUpdates();}

    private void requestLocationUpdates(){
          if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, MY_PERMISSION_REQUEST_FINE_LOCATION);
                }
                return;
            }
        LocationServices.FusedLocationApi.requestLocationUpdates(googleApiClient, locationRequest, this);
        }




    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }

    @Override
    protected void onStart() {
        super.onStart();
        if (permissionIsGranted) {
            googleApiClient.connect();
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (permissionIsGranted) {
            googleApiClient.disconnect();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
            case MY_PERMISSION_REQUEST_FINE_LOCATION:
                if(grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    permissionIsGranted = true;
                    Toast.makeText(this, "Permission Granted", Toast.LENGTH_LONG).show();
                }
                else{
                    permissionIsGranted = false;
                    Toast.makeText(getApplicationContext(), "This app requires location permissions to be granted", Toast.LENGTH_SHORT).show();
                    tvLatValue.setText("Lat permission denied");
                    tvLongValue.setText("Long permission denied");
                }
                break;

        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (permissionIsGranted){
        if (googleApiClient.isConnected())
            requestLocationUpdates();
    }}


    @Override
    protected void onPause() {
        super.onPause();
        if(permissionIsGranted) {
            LocationServices.FusedLocationApi.removeLocationUpdates(googleApiClient, this);
        }
    }

    @Override
    public void onLocationChanged(Location location) {
        if (permissionIsGranted){
    //Toast.makeText(this, "Location Changed:" + location.getLatitude() + " " + location.getLongitude(), Toast.LENGTH_LONG).show();
            longitude = location.getLongitude();
            latitude = location.getLatitude();
            tvLongValue.setText(Double.toString(longitude));
            tvLatValue.setText(Double.toString(latitude));



        }
    }

}

图像已保存到外部存储，但出现此错误：

                                                                               java.lang.RuntimeException: An error occurred while executing doInBackground()
                                                                              at android.os.AsyncTask$3.done(AsyncTask.java:309)
                                                                              at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
                                                                              at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
                                                                              at java.util.concurrent.FutureTask.run(FutureTask.java:242)
                                                                              at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
                                                                              at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
                                                                              at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
                                                                              at java.lang.Thread.run(Thread.java:818)
                                                                           Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.net.Uri.getPath()' on a null object reference
                                                                              at com.example.gary.natureallv2.CameraPicActivity$Encode_image.doInBackground(CameraPicActivity.java:217)
                                                                              at com.example.gary.natureallv2.CameraPicActivity$Encode_image.doInBackground(CameraPicActivity.java:214)

Answer 1

在 Encode_image 类中，file_url 似乎是 null。
它应该在onActivityResult 中调用new Encode_image().execute(); 之前进行初始化。
您是否在代码中的某处调用了getFileUri()？

Answer 2

不要访问异步任务中的全局变量。请将它们作为参数而不是 Void AsyncTask Uri 作为 Input 传递并返回 String 作为 output 。还提供检查 if (passed_uri != null)。请在模拟器中检查您在 Android v 21 上的代码，以检查您没有任何权限问题