不幸的是，应用程序已经停止，允许后允许或拒绝它的工作，但在一开始我会弹出我的应用程序已经停止

Question

我试图请求相机权限，但每当我运行我的项目，我得到我的应用程序已经停止弹出，然后它显示允许或拒绝选项，如果我点击永远不再显示选项，它不会让我按允许。如果我允许我的应用程序运行它存在，我再次必须打开应用程序。但问题会消失，我的应用程序将在下一次尝试中完美运行...这是logcat

07-26 18:41:56.080 3003-3003/com.example.android.camerapermissionE/Android运行时：致命异常：主进程：com.example.android.camerapermission，PID：3003java.lang.运行时异常：无法启动活动组件信息{com.example.android.camerapermission/com.example.android.camerapermission.MainActivity}：java.lang.运行时异常：未能连接到android.app.ActivityT的摄像机服务hread.perform启动活动（ActivityThread.java:2416）在android.app.ActivityThread.handle启动活动（ActivityThread.java:2476）在android.app.ActivityThread. wrap11（ActivityThread.java）在android.app.ActivityThread$H. handleMessage（ActivityThread.java:1344）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper. java： 148）在android. app. ActivityThread. main（ActivityThread. java： 5417）在java. lang. reect.法。调用（本机方法）在com. android. interal. os. ZygoteInit$MEodAndArgsCaller. run（ZygoteInit. java： 726）在com. android. interal. os. ZygoteInit. main（ZygoteInit. java： 616）造成：java. lang. Runtime异常：未能连接到android. hardware. Camera的摄像机服务。（相机。java： 495）在android. hardware。相机。打开（相机。java： 356）在com。示例。android. cammission。Mainactive. onCreed（Main

这是我的ctivity.java

 package com.example.android.camerapermission;

import android.Manifest;
import android.content.DialogInterface;

import android.content.pm.PackageManager;
import android.hardware.Camera;

import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.test.mock.MockPackageManager;
import android.util.Log;
import android.view.View;
import android.widget.ImageButton;
import android.widget.Toast;

import com.nispok.snackbar.Snackbar;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_CAMERA = 0;


    ImageButton imageButton;
    Camera camera;
    Camera.Parameters parameters;
    boolean isflash = false;
    boolean isOn = false;


    public static final String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageButton = (ImageButton) findViewById(R.id.imageButton);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(new String[] {Manifest.permission.CAMERA}, 0);
            }
        }
        if (getApplicationContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH))
            ;

        {
            camera = Camera.open();
            parameters = camera.getParameters();
            isflash = true;

        }


        imageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                if (isflash) {

                    if (!isOn) {
                        imageButton.setImageResource(R.drawable.on);
                        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
                        camera.setParameters(parameters);
                        camera.startPreview();
                        isOn = true;

                    } else {
                        imageButton.setImageResource(R.drawable.off);
                        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                        camera.setParameters(parameters);
                        camera.stopPreview();
                        isOn = false;
                    }


                } else {
                    AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                    builder.setTitle("Error.....");
                    builder.setMessage("Flashlight is not available on this device...");
                    builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {

                            dialog.dismiss();
                            finish();
                        }
                    });

                    AlertDialog alertDialog = builder.create();
                    alertDialog.show();
                }

            }
        });


    }

    public void showCamera(View view) {

        Log.i(TAG, "Show that camera button is clicked. Checking permission.");
        /**
         * Include camera permission and
         * check if camera is available in phone or not
         */
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
                != PackageManager.PERMISSION_GRANTED) {
            // Camera permission is not granted yet
            requestCameraPermission();
        } else {
            //Camera is available, show the camera preview

            Log.i(TAG, "CAMERA permission has granted, displaying camera preview");
            showCameraPreview();
        }

    }

    /**
     * Request the Camera Permission again in the case of user mistakenly denied permission.
     * Create a SnackBar that will prompt the user to grant the permission, otherwise it is requested direcly.
     */

    private void requestCameraPermission() {
        Log.i(TAG, " Camera permission is still not granted. Requesting permission.");

        //Start (camera_permission_request)
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.CAMERA)) {
            // show an additional request to the user if the permission was not granted earlier.


        } else {
            //Camera permission has not been granted yet. Request directly.
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA);
        }
        // END (camera_permission_request)
    }


    private void showCameraPreview() {
        getSupportFragmentManager().beginTransaction()
                .replace(R.id.sample_content_fragment, CameraPreviewFragment.newInstance())
                .commit();
    }


    /**
     * Receiving permission after granted
     */

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

        if (requestCode == REQUEST_CAMERA) {
            //Begin request (permission_result)
            //Recieved permission result for the camera permission.
            Log.i(TAG, "Request for Camera permission is received. ");

            //Check if the only required permission has been granted
            if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                //Camera permission is safely granted, now you can preview.
                Log.i(TAG, "Camera permission has succesfully granted, preview is being displayed");


            } else {
                Log.i(TAG, "CAMERA permission is not granted.");

                // Finish(permission_result)
            }

            super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        }

    }

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

        parameters = camera.getParameters();
        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
        camera.setParameters(parameters);
        camera.stopPreview();
        isflash = false;

        if (camera != null) {
            camera.release();
            camera = null;
        }
    }
}

注意：清单中已经设置了摄像头权限。xml。

Answer 1

让我们把它分解一下，这是你的代码：

1.  if (getApplicationContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH))
2.      ;
3.  {
        camera = Camera.open();
        parameters = camera.getParameters();
        isflash = true;
    }

事情就是这样。

1.  // If the system has a camera flash
2.  // Do nothing. The condition terminates here.
3.  // Open camera in any case.

要解决这个问题，请删除第2行的分号，并在将来注意分号。

Answer 2

你需要把打开摄像头的电话放在试一试中。

try {
        c = Camera.open(); // attempt to get a Camera instance
    }
    catch (Exception e){
        // Camera is not available (in use or does not exist)
    }

在Android开发者网站上，

Caution: Always check for exceptions when using Camera.open(). Failing to check for exceptions if the camera is in use or does not exist will cause your application to be shut down by the system.