java - Android相机应用程序: Outputting bitmap to second activity

Question

我想在内部保存图像，然后在下一个 Activity 中显示它。这是相机 Activity (预览和一切工作正常，但是当我按下“捕获”按钮时，我被发送到第二个 Activity ，但它只是一个白屏......没有显示位图图像)。

主要相机 Activity :

public class MainActivity extends FragmentActivity {


private static final String TAG = "CameraActivity";

public static final int MEDIA_TYPE_IMAGE = 1;
private Camera mCamera;
private CameraPreview mPreview;
private Context mContext;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mContext = this;

    if(checkCameraHardware(mContext)){
        // 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);

        // Add a listener to the Capture button
        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
                        mCamera.takePicture(null, null, mPicture);
                    }
                }
        );
    }
}

private Camera.PictureCallback mPicture = new Camera.PictureCallback() {

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

        new AsyncTask<Void, Void, String>() {

            @Override
            protected String doInBackground(Void... params) {


                try {
                    FileOutputStream fos = openFileOutput("img.jpg", Context.MODE_PRIVATE);
                    fos.write(data);
                    fos.close();
                     return "img.jpg";
                } catch (FileNotFoundException e) {
                    Log.d(TAG, "File not found: " + e.getMessage());
                    return null;
                } catch (IOException e) {
                    Log.d(TAG, "Error accessing file: " + e.getMessage());
                    return null;
                }
            }

            @Override
            protected void onPostExecute(String result) {
                super.onPostExecute(result);
                if(result != null){
                    Intent intent = new Intent(mContext,     ImageDisplayActivity.class);
                    intent.putExtra(ImageDisplayActivity.KEY_PATH,   "img.jpg");
                    startActivity(intent);
                }
            }

        }.execute();


    }
};
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;
    }
}
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
}
/** Create a File for saving an image or video */


}

这是第二个“显示图像” Activity :

public class ImageDisplayActivity extends FragmentActivity {

public static final String KEY_PATH = "img.jpg";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //final Bundle extras = getIntent().getExtras();
    Intent intent = getIntent();
    String path = getIntent().getStringExtra("EXTRA_FILE");

       try {
           java.io.FileInputStream in = this.openFileInput(path);
           Bitmap bitmap = BitmapFactory.decodeStream(in);
           ImageView mImg;
           mImg = (ImageView) findViewById(R.id.image_displayer);
           mImg.setRotation(90);
           mImg.setImageBitmap(bitmap);
           in.close();

       }
       catch(Exception e)
       {
         e.printStackTrace();
       }




}


private Bitmap decodeFile(File f){
    Bitmap b = null;
    try {
        BitmapFactory.Options o = new BitmapFactory.Options();
        FileInputStream fis = new FileInputStream(f);
        BitmapFactory.decodeStream(fis, null, o);
        fis.close();
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        fis = new FileInputStream(f);
        b = BitmapFactory.decodeStream(fis, null, o2);
        fis.close();
    } catch (IOException e) {
    }
    return b;
}

}

这是 LogCat:

02-26 00:56:05.905  12138-12138/com.commonsware.android.test1 W/System.err﹕ java.lang.NullPointerException

02-26 00:56:05.905  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ContextImpl.makeFilename(ContextImpl.java:2456)

02-26 00:56:05.905  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ContextImpl.openFileInput(ContextImpl.java:1072)

02-26 00:56:05.905  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.content.ContextWrapper.openFileInput(ContextWrapper.java:180)

02-26 00:56:05.905  12138-12138/com.commonsware.android.test1 W/System.err﹕ at com.commonsware.android.test1.ImageDisplayActivity.onCreate(ImageDisplayActivity.java:33)

02-26 00:56:05.915  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.Activity.performCreate(Activity.java:5372)

02-26 00:56:05.915  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)

02-26 00:56:05.915  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2267)

02-26 00:56:05.915  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359)

02-26 00:56:05.915  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ActivityThread.access$700(ActivityThread.java:165)

02-26 00:56:05.915  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1326)

02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:99)

02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.os.Looper.loop(Looper.java:137)

02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5455)

02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)

02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:525)    
02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at   com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187) 
02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003) 
02-26 00:56:05.925  12138-12138/com.commonsware.android.test1 W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)

Answer 1

使用ImageDisplayActivity.KEY_PATH作为key而不是EXTRA_FILE来获取从先前带有Intent的Activity传递的值:

String path = getIntent().getStringExtra(ImageDisplayActivity.KEY_PATH);