如何使用新的android.hardware.camera2接口显示摄像头预览？

import android.Manifest;
import android.content.pm.PackageManager;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CaptureRequest;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.Toast;

import java.util.Arrays;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_CAMERA_PERMISSION = 200;
    private static final String TAG = "Camera2Preview";

    private SurfaceView surfaceView;
    private SurfaceHolder surfaceHolder;
    private CameraManager cameraManager;
    private String cameraId;
    private CameraDevice cameraDevice;
    private CameraCaptureSession cameraCaptureSession;
    private CaptureRequest.Builder captureRequestBuilder;

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

        surfaceView = findViewById(R.id.surfaceView);
        surfaceHolder = surfaceView.getHolder();

        cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);

        surfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                openCamera();
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                // Surface已更改，可以重新设置预览大小等参数
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                closeCamera();
            }
        });
    }

    private void openCamera() {
        try {
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
                return;
            }
            cameraId = cameraManager.getCameraIdList()[0];
            cameraManager.openCamera(cameraId, new CameraDevice.StateCallback() {
                @Override
                public void onOpened(@NonNull CameraDevice camera) {
                    cameraDevice = camera;
                    createPreviewSession();
                }

                @Override
                public void onDisconnected(@NonNull CameraDevice camera) {
                    camera.close();
                    cameraDevice = null;
                }

                @Override
                public void onError(@NonNull CameraDevice camera, int error) {
                    camera.close();
                    cameraDevice = null;
                    Toast.makeText(MainActivity.this, "Camera error: " + error, Toast.LENGTH_SHORT).show();
                }
            }, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    private void createPreviewSession() {
        try {
            Surface surface = surfaceHolder.getSurface();

            captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
            captureRequestBuilder.addTarget(surface);

            cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
                @Override
                public void onConfigured(@NonNull CameraCaptureSession session) {
                    cameraCaptureSession = session;
                    try {
                        cameraCaptureSession.setRepeatingRequest(captureRequestBuilder.build(), null, null);
                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                    Toast.makeText(MainActivity.this, "Failed to configure camera session", Toast.LENGTH_SHORT).show();
                }
            }, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    private void closeCamera() {
        if (cameraCaptureSession != null) {
            cameraCaptureSession.close();
            cameraCaptureSession = null;
        }
        if (cameraDevice != null) {
            cameraDevice.close();
            cameraDevice = null;
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == REQUEST_CAMERA_PERMISSION) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                openCamera();
            } else {
                Toast.makeText(this, "Camera permission denied", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

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