java - 运行相机应用程序时出错

Question

我开始理解 andriod 应用程序代码并在我的设备上运行它。但是，当我运行代码并单击按钮时，设备说不幸的是相机已停止。如何解决此问题。这是我的 PhotoIntentActivity.java

package piyushs.camera;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;

public class PhotoIntentActivity extends Activity 
{
    private Camera mCamera;
    private CameraPreview mPreview;
    public static final int MEDIA_TYPE_IMAGE = 1;
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_photo_intent);
        Button captureButton = (Button) findViewById(R.id.button_capture);
        System.out.println("Starting!");
        // Create an instance of Camera
        mCamera = getCameraInstance();
        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this, mCamera);
        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mPreview);
        final PictureCallback mPicture = new PictureCallback() 
        {
            public void onPictureTaken(byte[] data, Camera camera) 
            {
                File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
                if (pictureFile == null)
                {
                    return;
                }
                try 
                {
                    FileOutputStream fos = new FileOutputStream(pictureFile);
                    fos.write(data);
                    fos.close();
                    MediaStore.Images.Media.insertImage(getContentResolver(), pictureFile.getAbsolutePath(), pictureFile.getName(), pictureFile.getName());
                } catch (FileNotFoundException e) 
                {
                } catch (IOException e) 
                {
                }
            }
        };
        // Add a listener to the Capture button
        captureButton.setOnClickListener
        (
            new View.OnClickListener() 
            {
                public void onClick(View v) 
                {
                    // get an image from the camera   
                    System.out.println("Photo Taking!");
                    mCamera.takePicture(null, null, mPicture);
                }
            }
        );
    }// end of oncreate()

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance()
    {
        Camera c = null;
        try 
        {
            c = Camera.open(); // attempt to get a Camera instance
        }
        catch (Exception e)
        {
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }
    @Override
    protected void onPause() 
    {
        super.onPause();
        releaseCamera();              // release the camera immediately on pause event
    }
    private void releaseCamera()
    {
        if (mCamera != null)
        {
            mCamera.release();        // release the camera for other applications
            mCamera = null;
        }
    }
    /** Create a File for saving an image or video */
    private  File getOutputMediaFile(int type)
    {
        // To be safe, you should check that the SDCard is mounted
        // using Environment.getExternalStorageState() before doing this.

        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
        Environment.DIRECTORY_PICTURES), "MyCameraApp");


        // This location works best if you want the created images to be shared
        // between applications and persist after your app has been uninstalled.
        // Create the storage directory if it does not exist
        if (! mediaStorageDir.exists())
        {
            if (! mediaStorageDir.mkdirs())
            {
                return null;
            }
        }
        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_IMAGE)
        {
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +"IMG_"+ timeStamp + ".jpg");
        } else 
        {
            return null;
        }
        return mediaFile;
    }
}

这是我的 CameraPreview.java

package piyushs.camera;
import android.content.Context;
import android.hardware.Camera;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback
{

    private SurfaceHolder mHolder;
    private Camera mCamera;

    public CameraPreview(Context context,Camera camera) 
    {
        super(context);
        mCamera = camera;

        /*SurfaceView view = new SurfaceView(this);
        c.setPreviewDisplay(view.getHolder());
        c.startPreview();
        c.takePicture(shutterCallback, rawPictureCallback, jpegPictureCallback);
         * */

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();

        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);   
    }
    public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) 
    {
        // TODO Auto-generated method stub
        if (mHolder.getSurface() == null)
        {
            // preview surface does not exist
            return;
        }
          // stop preview before making changes
          try 
          {
              mCamera.stopPreview();
          } catch (Exception e)
          {
            // ignore: tried to stop a non-existent preview
          }
          // set preview size and make any resize, rotate or
          // reformatting changes here
          // start preview with new settings
          try 
          {
              mCamera.setPreviewDisplay(mHolder);
              mCamera.startPreview();
          } catch (Exception e)
          {
          }
    }
    public void surfaceCreated(SurfaceHolder holder) 
    {
        // TODO Auto-generated method stub
    }
    public void surfaceDestroyed(SurfaceHolder holder) 
    {
        // TODO Auto-generated method stub
    }
}

这是我的activity_photo_intent.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
  <FrameLayout
    android:id="@+id/camera_preview"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_weight="1"
    />
    <Button
    android:id="@+id/button_capture"
    android:text="Capture"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    />

</LinearLayout>

我已经复制了 Building my own camera application + Automatically capture the image 中的大部分代码

Answer 1

在 list 中添加所需的权限和功能:

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