不幸的是，应用程序已停止运行，权限允许或允许后拒绝运行，但一开始我就弹出我的应用程序已停止的信息

Question

我正在尝试请求相机许可，但是无论何时我运行我的项目，我都首先停止弹出我的应用程序，然后如果我单击“从不再次显示”选项，它将显示“允许”或“拒绝”选项，它不会让我按“允许”。 如果我允许我的应用程序运行，则它存在，那么我又不得不打开应用程序。 但是问题将消失，我的应用程序将在下次尝试中完美运行。.这是logcat

07-26 18：41：56.080 3003-3003 / com.example.android.camerapermission E / AndroidRuntime：致命例外：主进程：com.example.android.camerapermission，PID：3003 java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.android.camerapermission / com.example.android.camerapermission.MainActivity}：java.lang.RuntimeException：无法在android上连接到android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2416）上的摄像头服务.app.ActivityThread.handleLaunchActivity（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.reflect.Method.invoke（ com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:726）上的com.android.internal.os.ZygoteInit.ma in（ZygoteInit.java:616）原因：java.lang.RuntimeException：无法连接到android.hardware.Camera。（Camera.java:495）上的android.hardware.Camera.open（Camera.java： 356），位于com.example.android.camerapermission.MainActivity.onCreate（MainActivity.java:52），位于android.app.Activity.performCreate（Activity.java:6237），位于android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1107） ）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2369）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2476）在android.app.ActivityThread.-wrap11（ActivityThread.java）在android.app.ActivityThread。位于android.os.Handler.dispatchMessage（Handler.java:102）的ActivityThread $ H.handleMessage（ActivityThread.java:1344）位于android.app.ActivityThread.main的android.os.Looper.loop（Looper.java:148） （ActivityThread.java:5417）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:726）上的java.lang.reflect.Method.invoke（本机方法） t com.android.internal.os.ZygoteInit.main（ZygoteInit.java:616）

这是我的MainActivity.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：相机许可已在Manifest.xml中设置。

Answer 1

您需要将摄像头打开呼叫包含在try catch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.

Answer 2

让我们分解一下，这是您的代码：

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

这就是发生的情况。

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

要解决此问题，请删除第2行上的杂散分号，并在以后注意分号。