尝试使用 Android Camera2 创建手电筒

Question

我正在尝试使用 Camera2 创建手电筒。我收到错误。当我尝试打开或关闭手电筒时，我收到错误消息：

android.hardware.camera2.CameraAccessExeption: The camera device has encountered a serious error.

主要活动

package com.nettport.lommelykt;

import android.Manifest;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ToggleButton;
import android.content.Context;
import android.graphics.SurfaceTexture;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CameraMetadata;
import android.hardware.camera2.CaptureRequest;
import android.util.Size;
import android.view.Surface;
import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity {
    CameraManager cameraManager;
    CameraCharacteristics cameraCharacteristics;

    CameraDevice mCameraDevice;
    CameraCaptureSession mSession;

    CaptureRequest.Builder mBuilder;


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

        // Initialize camera
        initCamera();

        // Click button on or off
        ToggleButton onOffButton = (ToggleButton) findViewById(R.id.toggleButton);
        onOffButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // your click actions go here
                if (((ToggleButton) v).isChecked()) {
                    changeTextAndIcon(1);
                    turnOnFlashLight();
                } else {
                    changeTextAndIcon(0);
                    turnOffFlashLight();
                }
            }
        });

    }

    /*- Change text and icon ------------------------------------- */
    // modus = 1 -> turn on
    // modus = 0 -> turn off
    void changeTextAndIcon(int modus) {
        // Change text
        TextView statusText = (TextView) findViewById(R.id.textView);
        if (modus == 1) {
            statusText.setText("Lommelykten er på"); // Flash  is on
        } else {
            statusText.setText("Lommelykten er av"); // Flash is off
        }

        // Change icon to off
        ImageView flashlightIcon = (ImageView) findViewById(R.id.imageView);
        if (modus == 1) {
            flashlightIcon.setImageResource(R.drawable.flashlight_on);
        } else {
            flashlightIcon.setImageResource(R.drawable.flashlight_off);
        }
    }

    private void initCamera() {
        cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        try {
            String[] id = cameraManager.getCameraIdList();
            if (id != null && id.length > 0) {
                cameraCharacteristics = cameraManager.getCameraCharacteristics(id[0]);
                boolean isFlash = cameraCharacteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
                if (isFlash) {
                    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                        // TODO: Consider calling
                        //    ActivityCompat#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for ActivityCompat#requestPermissions for more details.
                        return;
                    }
                    cameraManager.openCamera(id[0], new MyCameraDeviceStateCallback(), null);
                    Toast.makeText(this, "Camera initialized", Toast.LENGTH_LONG).show();
                }
            }
        }
        catch (CameraAccessException e)
        {
            e.printStackTrace();
            Toast.makeText(this, "Camera initialization error:\n" + e.toString(), Toast.LENGTH_LONG).show();
        }
    }

    class MyCameraDeviceStateCallback extends CameraDevice.StateCallback
    {

        @Override
        public void onOpened(CameraDevice camera)
        {
            mCameraDevice = camera;
            // get builder
            try
            {
                mBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                List<Surface> list = new ArrayList<Surface>();
                SurfaceTexture mSurfaceTexture = new SurfaceTexture(1);
                Size size = getSmallestSize(mCameraDevice.getId());
                mSurfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight());
                Surface mSurface = new Surface(mSurfaceTexture);
                list.add(mSurface);
                mBuilder.addTarget(mSurface);
                camera.createCaptureSession(list, new MyCameraCaptureSessionStateCallback(), null);
            }
            catch (CameraAccessException e)
            {
                e.printStackTrace();

            }
        }

        @Override
        public void onDisconnected(CameraDevice camera)
        {

        }

        @Override
        public void onError(CameraDevice camera, int error)
        {

        }
    }

    private Size getSmallestSize(String cameraId) throws CameraAccessException
    {
        Size[] outputSizes = cameraManager.getCameraCharacteristics(cameraId).get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(SurfaceTexture.class);
        if (outputSizes == null || outputSizes.length == 0)
        {
            throw new IllegalStateException("Camera " + cameraId + "doesn't support any outputSize.");
        }
        Size chosen = outputSizes[0];
        for (Size s : outputSizes)
        {
            if (chosen.getWidth() >= s.getWidth() && chosen.getHeight() >= s.getHeight())
            {
                chosen = s;
            }
        }
        return chosen;
    }
    class MyCameraCaptureSessionStateCallback extends CameraCaptureSession.StateCallback
    {
        @Override
        public void onConfigured(CameraCaptureSession session)
        {
            mSession = session;
            try
            {
                mSession.setRepeatingRequest(mBuilder.build(), null, null);
            }
            catch (CameraAccessException e)
            {
                e.printStackTrace();
            }
        }

        @Override
        public void onConfigureFailed(CameraCaptureSession session)
        {

        }
    }

    public void turnOnFlashLight()
    {
        try
        {
            mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH);
            mSession.setRepeatingRequest(mBuilder.build(), null, null);
            Toast.makeText(this, "Flash activated", Toast.LENGTH_LONG).show();
        }
        catch (Exception e)
        {
            e.printStackTrace();
            Toast.makeText(this, "Flash failed:\n" + e.toString(), Toast.LENGTH_LONG).show();
        }
    }

    public void turnOffFlashLight()
    {
        try
        {
            mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_OFF);
            mSession.setRepeatingRequest(mBuilder.build(), null, null);
            Toast.makeText(this, "Flash disabled", Toast.LENGTH_LONG).show();
        }
        catch (Exception e)
        {
            e.printStackTrace();
            Toast.makeText(this, "Flash failed:\n" + e.toString(), Toast.LENGTH_LONG).show();
        }
    }

    private void close()
    {
        Toast.makeText(this, "Camera closed", Toast.LENGTH_LONG).show();
        if (mCameraDevice == null || mSession == null)
        {
            return;
        }
        mSession.close();
        mCameraDevice.close();
        mCameraDevice = null;
        mSession = null;
    }

}

AndroidManifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.nettport.lommelykt">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        >
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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


    <!-- Allows access to the flashlight -->

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.FLASHLIGHT" />

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


</manifest>

Answer 1

你没有抓住你的 SurfaceTexture；从它创建的 Surface 大致相当于一个弱指针，并且不会阻止 SurfaceTexture 被垃圾收集。

查看将 SurfaceTexture 存储在 MainActivity 中是否可以解决您的问题。如果不是，您将需要提供 logcat 崩溃（不仅仅是应用程序日志记录，整个系统）以更详细地查看相机服务抱怨的内容。

尝试使用 Android Camera2 创建手电筒

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