<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <SurfaceView
        android:id="@+id/sfv_preview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1" />

</LinearLayout>

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

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

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

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

    </application>

</manifest>　　

package com.gatsby.ypcamerdemo;

import android.hardware.Camera;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import androidx.appcompat.app.AppCompatActivity;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private SurfaceView sfv_preview;
    private Camera camera = null;
    private SurfaceHolder.Callback cpHolderCallback = new SurfaceHolder.Callback() {
        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            startPreview();
        }

        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

        }

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

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

    private void bindViews() {
        sfv_preview = (SurfaceView) findViewById(R.id.sfv_preview);
        sfv_preview.getHolder().addCallback(cpHolderCallback);
    }

    //开始预览
    private void startPreview() {
        camera = Camera.open();
        try {
            camera.setPreviewDisplay(sfv_preview.getHolder());
            camera.setDisplayOrientation(0);
            camera.startPreview();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //停止预览
    private void stopPreview() {
        camera.stopPreview();
        camera.release();
        camera = null;
    }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextureView
        android:id="@+id/textureview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

package com.gatsby.textureviewtest;

import android.annotation.SuppressLint;
import android.annotation.TargetApi;
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.CaptureRequest;
import android.hardware.camera2.CaptureResult;
import android.hardware.camera2.TotalCaptureResult;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;
import android.view.Surface;
import android.view.TextureView;

import androidx.appcompat.app.AppCompatActivity;

import java.util.Arrays;

public class MainActivity extends AppCompatActivity {

    private TextureView textureView;
    private String TAG="Gatsby";

    private HandlerThread mThreadHandler;
    private Handler mHandler;

    private CaptureRequest.Builder mPreviewBuilder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mThreadHandler = new HandlerThread("CAMERA2");
        mThreadHandler.start();
        mHandler = new Handler(mThreadHandler.getLooper());

        textureView= (TextureView) findViewById(R.id.textureview);
        textureView.setSurfaceTextureListener(textureListener);

    }

    private TextureView.SurfaceTextureListener textureListener=new TextureView.SurfaceTextureListener() {
        @SuppressLint("MissingPermission")
        @TargetApi(Build.VERSION_CODES.LOLLIPOP)
        @Override
        public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int i, int i1) {
            Log.e(TAG,"可用");

            //CameraManaer 摄像头管理器，用于检测摄像头，打开系统摄像头
            CameraManager cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);
            try {
                String[] CameraIdList=cameraManager.getCameraIdList();//获取可用相机列表
                Log.e(TAG,"可用相机的个数是:"+CameraIdList.length);
                //获取某个相机(摄像头特性)
                CameraCharacteristics cameraCharacteristics=cameraManager.getCameraCharacteristics(CameraIdList[0]);
                cameraCharacteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);//检查支持
                cameraManager.openCamera(CameraIdList[0],mCameraDeviceStateCallback, mHandler);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }

        }

        @Override
        public void onSurfaceTextureSizeChanged(SurfaceTexture surfaceTexture, int i, int i1) {
            Log.e(TAG,"change");
        }

        @Override
        public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
            Log.e(TAG,"destroy");
            return false;
        }

        @Override
        public void onSurfaceTextureUpdated(SurfaceTexture surfaceTexture) {
            Log.e(TAG,"update");
        }
    };

    //CameraDeviceandroid.hardware.Camera也就是Camera1的Camera
    private CameraDevice.StateCallback mCameraDeviceStateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(CameraDevice camera) {
            try {
                startPreview(camera);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onDisconnected(CameraDevice camera) {

        }

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

        }
    };

    /**
     * @param camera
     * @throws CameraAccessException
     * 开始预览
     */
    private void startPreview(CameraDevice camera) throws CameraAccessException {
        SurfaceTexture texture = textureView.getSurfaceTexture();
        texture.setDefaultBufferSize(textureView.getWidth(), textureView.getHeight());
        Surface surface = new Surface(texture);
        try {
            //CameraRequest表示一次捕获请求，用来对z照片的各种参数设置，比如对焦模式、曝光模式等。CameraRequest.Builder用来生成CameraRequest对象
            mPreviewBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);

        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
        mPreviewBuilder.addTarget(surface);
        camera.createCaptureSession(Arrays.asList(surface), mSessionStateCallback, mHandler);
    }

    //CameraCaptureSession 这个对象控制摄像头的预览或者拍照
    //setRepeatingRequest()开启预览，capture()拍照
    //StateCallback监听CameraCaptureSession的创建
    private CameraCaptureSession.StateCallback mSessionStateCallback = new CameraCaptureSession.StateCallback() {
        @Override
        public void onConfigured(CameraCaptureSession session) {
            Log.e(TAG,"相机创建成功！");
            try {
                session.capture(mPreviewBuilder.build(), mSessionCaptureCallback, mHandler);//拍照
                session.setRepeatingRequest(mPreviewBuilder.build(), mSessionCaptureCallback, mHandler);//返回结果
            } catch (CameraAccessException e) {
                e.printStackTrace();
                Log.e(TAG,"这里异常");
            }
        }

        @Override
        public void onConfigureFailed(CameraCaptureSession session) {
            Log.e(TAG,"相机创建失败！");
        }
    };


    //CameraCaptureSession.CaptureCallback监听拍照过程
    private CameraCaptureSession.CaptureCallback mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {

        @Override
        public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
            Log.e(TAG,"这里接受到数据"+result.toString());
        }

        @Override
        public void onCaptureProgressed(CameraCaptureSession session, CaptureRequest request, CaptureResult partialResult){

        }};
}