Java 通过线性布局为摄像头提供白色屏幕

很抱歉在这里贴了一堆文字，但我不知道还能做什么

我认为这与清单中缺少CameraPreview有关，但我不确定，也不知道如何在扩展视图时将其添加到清单中。无论如何，应用程序是针对我的设备的适当sdk运行的，然后只显示一个白色屏幕和“捕获”按钮。我尝试使用SurfaceView，但无法将mpreview添加到视图中。非常困惑，希望得到任何帮助或指点。多谢各位

CameraActivity.java：

package installation04.myapplication;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.camera2.CameraManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;


public class CameraActivity extends Activity{

private Camera mCamera;
private CameraPreview mPreview;
private CameraManager mManager;
private String[] mCameraIds;
private SurfaceHolder mHolder;
private SurfaceHolder holder;

public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
private static final String TAG = "CameraPreview";

LinearLayout camera_preview;
Button button_capture;

public CameraActivity() {
    super();
}

@Override
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_camera);

    button_capture = (Button) findViewById(R.id.button_capture);
    if(checkCameraHardware(getApplicationContext())){
        getCameraInstance();
    }

    // Create our Preview view and set it as the content of our activity.
    mPreview = new CameraPreview(this, mCamera);
    LinearLayout preview = (LinearLayout) findViewById(R.id.camera_preview);
    preview.addView(mPreview);
}

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
}

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: ");
        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());
    }
}

/** Create a file Uri for saving an image or video */
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_HH:mm:ss").format(new Date());
    File mediaFile;
    if (type == MEDIA_TYPE_IMAGE){
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                "IMG_"+ timeStamp + ".jpg");
    } else if(type == MEDIA_TYPE_VIDEO) {
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                "VID_"+ timeStamp + ".mp4");
    } else {
        return null;
    }

    return mediaFile;
}

public void onClick() {
    // Add a listener to the Capture button
    Button captureButton = (Button) findViewById(R.id.button_capture);
    captureButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View arg0) {
        }
    });
}
}

CameraPreview.java：

package installation04.myapplication;

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

import java.io.IOException;

public class CameraPreview extends View  implements SurfaceHolder.Callback{

private static final String TAG = "CameraPreview: ";
private Camera mCamera;
private SurfaceHolder mHolder;
private SurfaceHolder holder;

public CameraPreview(Context context) {
    super(context);
}
public CameraPreview(Context context, AttributeSet attrs) {
    super(context, attrs);
}

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

    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = getHolder();
    // deprecated setting, but required on Android versions prior to 3.0
    if (mHolder != null) {
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }
}

private SurfaceHolder getHolder() {
    return null;
}

public void surfaceCreated(SurfaceHolder holder) {
    // The Surface has been created, now tell the camera where to draw the preview.
    try {
        mCamera.setDisplayOrientation(90);
        mCamera.setPreviewDisplay(holder);
        mCamera.startPreview();
    } catch (IOException e) {
        Log.d(TAG, "Error setting camera preview: " + e.getMessage());
    }
}

public void surfaceDestroyed(SurfaceHolder holder) {
    // empty. Take care of releasing the Camera preview in your activity.
}

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 (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){
        Log.d(TAG, "Error starting camera preview: " + e.getMessage());
    }
}
}

AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:viewandroid="http://schemas.android.com/apk/res-auto"
package="installation04.myapplication">
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera2" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity
        android:name=".CameraActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>


</application>

</manifest>

---

我不清楚你在问什么，如果你不想要预览，而是想要一个白色屏幕，不要添加prieview

//remove this line from on create
 preview.addView(mPreview);

并为布局提供白色背景