java - Android 代码无法访问手机摄像头...出了什么问题？

Question

我在使用相机预览时遇到问题。有什么想法吗？我认为我的代码无法连接/找到手机上的摄像头...我在编程方面非常陌生。

错误消息如下:

07-31 22:10:29.940 26291-26291/user.cameratest W/CameraBase: An error occurred while connecting to camera: 0
07-31 22:10:30.168 26291-26320/user.cameratest E/Surface: getSlotFromBufferLocked: unknown buffer: 0xb9bfa3e8
07-31 22:10:30.191 26291-26291/user.cameratest W/CameraBase: An error occurred while connecting to camera: 0
07-31 22:10:36.957 26291-26320/user.cameratest E/Surface: getSlotFromBufferLocked: unknown buffer: 0xb9c89198
07-31 22:10:40.458 26291-26320/user.cameratest E/Surface: getSlotFromBufferLocked: unknown buffer: 0xb9b47570

这是代码:

AndroidManifest.XML

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="user.cameratest">

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

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<!--uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /-->

<application
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name" >
    <activity
        android:label="@string/app_name"
        android:name=".cameraActivity"
        android:screenOrientation="landscape" >
        <intent-filter >
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

cameraActivity.java

package user.cameratest;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.Toast;

public class cameraActivity extends Activity { //
    private static final String TAG = "cameraActivity";
    cameraPreview preview;
    Button buttonClick;
    Camera camera; //
    Activity act;
    Context ctx;

    @Override
    public void onCreate(Bundle savedInstanceState) { //
        super.onCreate(savedInstanceState); //
        ctx = this;
        act = this;
        requestWindowFeature(Window.FEATURE_NO_TITLE); //
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); //

        setContentView(R.layout.camera_layout);  //

        preview = new cameraPreview(this, (SurfaceView)findViewById(R.id.surfaceView));
        preview.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
        ((FrameLayout) findViewById(R.id.layout)).addView(preview);
        preview.setKeepScreenOn(true);

        preview.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                camera.takePicture(shutterCallback, rawCallback, jpegCallback);
            }
        });

        Toast.makeText(ctx, getString(R.string.take_photo_help), Toast.LENGTH_LONG).show();

        //      buttonClick = (Button) findViewById(R.id.btnCapture);
        //
        //      buttonClick.setOnClickListener(new OnClickListener() {
        //          public void onClick(View v) {
        ////                preview.camera.takePicture(shutterCallback, rawCallback, jpegCallback);
        //              camera.takePicture(shutterCallback, rawCallback, jpegCallback);
        //          }
        //      });
        //
        //      buttonClick.setOnLongClickListener(new OnLongClickListener(){
        //          @Override
        //          public boolean onLongClick(View arg0) {
        //              camera.autoFocus(new AutoFocusCallback(){
        //                  @Override
        //                  public void onAutoFocus(boolean arg0, Camera arg1) {
        //                      //camera.takePicture(shutterCallback, rawCallback, jpegCallback);
        //                  }
        //              });
        //              return true;
        //          }
        //      });
    }

    @Override
    protected void onResume() {
        super.onResume();
        int numCams = Camera.getNumberOfCameras();
        if(numCams > 0){
            try{
                camera = Camera.open(0);
                camera.startPreview();
                preview.setCamera(camera);
            } catch (RuntimeException ex){
                Toast.makeText(ctx, getString(R.string.camera_not_found), Toast.LENGTH_LONG).show();
            }
        }
    }

    @Override
    protected void onPause() {
        if(camera != null) {
            camera.stopPreview();
            preview.setCamera(null);
            camera.release();
            camera = null;
        }
        super.onPause();
    }

    private void resetCam() {
        camera.startPreview();
        preview.setCamera(camera);
    }

    private void refreshGallery(File file) {
        Intent mediaScanIntent = new Intent( Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        mediaScanIntent.setData(Uri.fromFile(file));
        sendBroadcast(mediaScanIntent);
    }

    ShutterCallback shutterCallback = new ShutterCallback() {
        public void onShutter() {
            //           Log.d(TAG, "onShutter'd");
        }
    };

    PictureCallback rawCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            //           Log.d(TAG, "onPictureTaken - raw");
        }
    };

    PictureCallback jpegCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            new SaveImageTask().execute(data);
            resetCam();
            Log.d(TAG, "onPictureTaken - jpeg");
        }
    };

    private class SaveImageTask extends AsyncTask<byte[], Void, Void> {

        @Override
        protected Void doInBackground(byte[]... data) {
            FileOutputStream outStream = null;

            // Write to SD Card
            try {
                File sdCard = Environment.getExternalStorageDirectory();
                File dir = new File (sdCard.getAbsolutePath() + "/camtest");
                dir.mkdirs();

                String fileName = String.format("%d.jpg", System.currentTimeMillis());
                File outFile = new File(dir, fileName);

                outStream = new FileOutputStream(outFile);
                outStream.write(data[0]);
                outStream.flush();
                outStream.close();

                Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length + " to " + outFile.getAbsolutePath());

                refreshGallery(outFile);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
            }
            return null;
        }

    }
}

cameraPreview.java

package user.cameratest;

/**
 * @author Jose Davis Nidhin
 */

import java.io.IOException;
import java.util.List;

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

class cameraPreview extends ViewGroup implements SurfaceHolder.Callback { //
    private final String TAG = "cameraPreview"; //

    SurfaceView mSurfaceView; //
    SurfaceHolder mHolder; //
    Size mPreviewSize; //
    List<Size> mSupportedPreviewSizes; //
    Camera mCamera; //

    cameraPreview(Context context, SurfaceView sv) { //
        super(context); //

        mSurfaceView = sv; //
//        addView(mSurfaceView);

        mHolder = mSurfaceView.getHolder(); //
        mHolder.addCallback(this); //
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); //
    }

    public void setCamera(Camera camera) { //
        mCamera = camera; //
        if (mCamera != null) { //
            mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes(); //
            requestLayout(); //

            // get Camera parameters
            Camera.Parameters params = mCamera.getParameters(); //

            List<String> focusModes = params.getSupportedFocusModes(); //
            if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) { //
                // set the focus mode
                params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO); //
                // set Camera parameters
                mCamera.setParameters(params); //
            }
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { //
        // We purposely disregard child measurements because act as a
        // wrapper to a SurfaceView that centers the camera preview instead
        // of stretching it.
        final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec); //
        final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec); //
        setMeasuredDimension(width, height); //

        if (mSupportedPreviewSizes != null) { //
            mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height); //
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) { //
        if (changed && getChildCount() > 0) {
            final View child = getChildAt(0);

            final int width = r - l;
            final int height = b - t;

            int previewWidth = width;
            int previewHeight = height;
            if (mPreviewSize != null) {
                previewWidth = mPreviewSize.width;
                previewHeight = mPreviewSize.height;
            }

            // Center the child SurfaceView within the parent.
            if (width * previewHeight > height * previewWidth) {
                final int scaledChildWidth = previewWidth * height / previewHeight;
                child.layout((width - scaledChildWidth) / 2, 0,
                        (width + scaledChildWidth) / 2, height);
            } else {
                final int scaledChildHeight = previewHeight * width / previewWidth;
                child.layout(0, (height - scaledChildHeight) / 2,
                        width, (height + scaledChildHeight) / 2);
            }
        }
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, acquire the camera and tell it where
        // to draw.
        try {
            if (mCamera != null) {
                mCamera.setPreviewDisplay(holder);
            }
        } catch (IOException exception) {
            Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        if (mCamera != null) {
            mCamera.stopPreview();
        }
    }


    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) w / h;
        if (sizes == null) return null;

        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        // Try to find an size match aspect ratio and size
        for (Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        // Cannot find the one match the aspect ratio, ignore the requirement
        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes) {
                if (Math.abs(size.height - targetHeight) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if(mCamera != null) {
            Camera.Parameters parameters = mCamera.getParameters();
            parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
            requestLayout();

            mCamera.setParameters(parameters);
            mCamera.startPreview();
        }
    }

}

camera_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <SurfaceView
        android:id="@+id/surfaceView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <!-- Button
        android:id="@+id/btnCapture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:background="@drawable/round_button"
        android:text="@string/btn_capture" /-->

</FrameLayout>

Answer 1

您是否请求权限？: https://developer.android.com/training/permissions/requesting.html

对于相机，权限为Manifest.permission.CAMERA。

另外 android.hardware.camera 已被弃用，您应该使用 android.hardware.camera2 https://developer.android.com/reference/android/hardware/camera2/package-summary.html