在android中拍照失败

Question

我查了所有相关的帖子，没有找到答案。 我试图用相机库拍照，但拍照方法失败了。 代码假设要做的是按下按钮在ImageView上显示图像（这听起来很简单）。 该应用程序在拍摄时会崩溃，最后会附加堆栈跟踪。

MainActivity.java

package com.drivesafe.drivesafe;


import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.*;
import android.view.*;
import android.widget.*;
import android.hardware.Camera;
import java.util.Timer;


public class MainActivity extends AppCompatActivity {

    public static ProgressDialog detectionProgressDialog;
    public static ImageView imageView;
    public static Camera camera;
    public static Camera.PictureCallback pictureCallback;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.imageView = (ImageView)findViewById(R.id.imageView1);
        Button button1 = (Button)findViewById(R.id.button1);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                take_picture();
            }

        });
        this.detectionProgressDialog = new ProgressDialog(this);
        this.pictureCallback = new PhotoHandler(getApplicationContext());
        this.initFrontCamera();
    }
    private void take_picture() {
        camera.startPreview();
        camera.takePicture(null, null, null, this.pictureCallback);
    }

    private void initFrontCamera() {
        camera = Camera.open(1); //front camera
    }

}

PhotoHandler.java

package com.drivesafe.drivesafe;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.os.AsyncTask;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.widget.ImageView;
import android.widget.Toast;

public class PhotoHandler implements PictureCallback  {
    private final Context context;

    public PhotoHandler(Context context) {
        this.context = context;
    }

    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
        MainActivity.imageView.setImageBitmap(bitmap);
    }
}

堆栈追踪：

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.drivesafe.drivesafe, PID: 28460
              java.lang.RuntimeException: takePicture failed
                  at android.hardware.Camera.native_takePicture(Native Method)
                  at android.hardware.Camera.takePicture(Camera.java:1545)
                  at com.drivesafe.drivesafe.MainActivity.take_picture(MainActivity.java:43)
                  at com.drivesafe.drivesafe.MainActivity.access$000(MainActivity.java:13)
                  at com.drivesafe.drivesafe.MainActivity$1.onClick(MainActivity.java:29)
                  at android.view.View.performClick(View.java:5637)
                  at android.view.View$PerformClick.run(View.java:22433)
                  at android.os.Handler.handleCallback(Handler.java:751)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:154)
                  at android.app.ActivityThread.main(ActivityThread.java:6121)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)
   Application terminated.

权限

<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-feature android:name="android.hardware.camera"
    android:required="true" />

我希望得到一些帮助。