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！
答案 0 :(得分：0)
稍后尝试getCameraInstance（），例如调用onStart（）