Question

嘿那里我是应用程序开发的新手，我正在尝试构建一个包含相机的应用程序。我按照Android开发人员指南，然后应用程序将无法运行，在尝试寻找此站点中的旧答案，而没有找到任何帮助我，我要求你的帮助。这是我的代码：

package com.example.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.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;

public class MainActivity extends Activity {
public static final int MEDIA_TYPE_IMAGE = 1;
public static String TAG="MainActivity";
private Camera camera;
private CameraPreview preview;
private PictureCallback picture;
private FileNotFoundException err;
public static Camera getCameraInstance(){
    Camera c = null;
    try {
        c = Camera.open(); // attempt to get a Camera insta
    }
    catch (Exception e){
        // Camera is not available (in use or does not exist)
    }
    return c; // returns null if camera is unavailable
}
private boolean checkCameraHardware(Context context) {
    if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
        // this device has a camera
        return true;
    } else {
        // no camera on this device
        return false;
    }
}
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    camera = getCameraInstance();
    preview = new CameraPreview(this, camera);
    FrameLayout FLpreview = (FrameLayout) findViewById(R.id.camera_preview);
    FLpreview.addView(preview);

    picture = new PictureCallback() {

        @Override
        public void onPictureTaken(byte[] data, Camera camera) {

            File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
            if (pictureFile == null){
                Log.d(TAG, "Error creating media file, check storage permissions: "+ err.getMessage());
                return;
            }

            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {
                Log.d(TAG, "File not found: " + e.getMessage());
            } catch (IOException e) {
                Log.d(TAG, "Error accessing file: " + e.getMessage());
            }
        }
    };
    Button captureButton = (Button) findViewById(R.id.button_capture);
    captureButton.setOnClickListener(
        new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // get an image from the camera
                camera.takePicture(null, null, picture);
            }
        }
    );
}
/** A safe way to get an instance of the Camera object. */


  private void releaseCamera(){
        if (camera != null){
            camera.release();        // release the camera for other applications
            camera = null;
        }
    }
  private static Uri getOutputMediaFileUri(int type){
      return Uri.fromFile(getOutputMediaFile(type));
}
  /** Create a File for saving an image or video */
  private static 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()){
              Log.d("MyCameraApp", "failed to create directory");
              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;
  }

}

这里是surfaceholder的代码：

package com.example.camera;

import java.io.IOException;

import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder holder;
private Camera camera;
public static String TAG="MainActivity";
public CameraPreview(Context context, Camera cam) {
    super(context);
    camera=cam;
    holder=getHolder();
    holder.addCallback(this);
    holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
    camera.setPreviewDisplay(holder);
    camera.startPreview();
} catch (IOException e) {
    Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.

if (holder.getSurface() == null){
  // preview surface does not exist
  return;
}

// stop preview before making changes
try {
    camera.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 {
    camera.setPreviewDisplay(holder);
    camera.setDisplayOrientation(0);
    camera.startPreview();

} catch (Exception e){
    Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}


}

最后，Logcat：

07-31 12:06:06.361: W/Camera(998): ICamera died
07-31 12:06:06.361: W/Camera(998): Camera server died!
07-31 12:06:06.381: E/Camera(998): Error 100

非常感谢！

Answer 1

稍后尝试getCameraInstance（），例如调用onStart（）

在android上构建相机应用程序

1 个答案: