Camera2 API简介

Android 从5.0（21）开始，引入了新的Camera API Camera2，原来的android.hardware.Camera被废弃(下面称为Camera1)，还有一个android.graphics.Camera，这个android.graphics.Camera不是用来照相的，是用来处理图像的，可以做出3D的图像效果之类的，之前的Camera1则由android.hardware.Camera代替。Camera2支持RAW输出，可以调节曝光，对焦模式，快门等，功能比原先Camera强大。

这里引用了管道的概念将安卓设备和摄像头之间联通起来，系统向摄像头发送 Capture 请求，而摄像头会返回 CameraMetadata。这一切建立在一个叫作 CameraCaptureSession 的会话中。

CameraManaer 摄像头管理器，用于检测摄像头，打开系统摄像头，调用CameraManager.getCameraCharacteristics(String)可以获取指定摄像头的相关特性

CameraCharacteristics 摄像头的特性

CameraDevice 摄像头，类似android.hardware.Camera也就是Camera1的Camera

CameraCaptureSession 这个类控制摄像头的预览或者拍照，setRepeatingRequest()开启预览，capture()拍照，CameraCaptureSession提供了StateCallback、CaptureCallback两个接口来监听CameraCaptureSession的创建和拍照过程。

CameraRequest和CameraRequest.Builder，预览或者拍照时，都需要一个CameraRequest对象。CameraRequest表示一次捕获请求，用来对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。

Camera2的简单使用（使用SurfaceView）

主要步骤：

获得摄像头管理器CameraManager mCameraManager，mCameraManager.openCamera()来打开摄像头
指定要打开的摄像头，并创建openCamera()所需要的CameraDevice.StateCallback stateCallback
在CameraDevice.StateCallback stateCallback中调用takePreview()，这个方法中，使用CaptureRequest.Builder创建预览需要的CameraRequest，并初始化了CameraCaptureSession，最后调用了setRepeatingRequest(previewRequest, null, childHandler)进行了预览
点击拍照按钮，调用takePicture()，这个方法内，最终调用了capture(mCaptureRequest, null, childHandler)
在new ImageReader.OnImageAvailableListener(){}回调方法中，将拍照拿到的图片进行展示

package org.hunter.a361camera.view;import android.Manifest;import android.content.Context;import android.content.pm.PackageManager;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.ImageFormat;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.media.Image;import android.media.ImageReader;import android.os.Build;import android.os.Bundle;import android.os.Handler;import android.os.HandlerThread;import android.support.annotation.Nullable;import android.support.annotation.RequiresApi;import android.support.v4.app.ActivityCompat;import android.support.v4.app.Fragment;import android.util.SparseIntArray;import android.view.LayoutInflater;import android.view.Surface;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.Toast;import org.hunter.a361camera.R;import java.nio.ByteBuffer;import java.util.Arrays;import static android.os.Looper.getMainLooper;/** * Main UI for the statistics screen. */public class CameraFragment extends Fragment {    public static final int REQUEST_CAMERA_CODE = 100;    public static final String PACKAGE = "package:";    private static final SparseIntArray ORIENTATIONS = new SparseIntArray();    ///为了使照片竖直显示    static {        ORIENTATIONS.append(Surface.ROTATION_0, 90);        ORIENTATIONS.append(Surface.ROTATION_90, 0);        ORIENTATIONS.append(Surface.ROTATION_180, 270);        ORIENTATIONS.append(Surface.ROTATION_270, 180);    }    private SurfaceView mSurfaceView;    private SurfaceHolder mSurfaceHolder;    private ImageView iv_show;    private ImageView mCatture;    private CameraManager mCameraManager;//摄像头管理器    private Handler childHandler, mainHandler;    private String mCameraID;//摄像头Id 0 为后  1 为前    private ImageReader mImageReader;    private CameraCaptureSession mCameraCaptureSession;    private CameraDevice mCameraDevice;    /**     * 摄像头创建监听     */    private CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {        @Override        public void onOpened(CameraDevice camera) {//打开摄像头            mCameraDevice = camera;            //开启预览            takePreview();        }        @Override        public void onDisconnected(CameraDevice camera) {//关闭摄像头            if (null != mCameraDevice) {                mCameraDevice.close();                CameraFragment.this.mCameraDevice = null;            }        }        @Override        public void onError(CameraDevice camera, int error) {//发生错误            Toast.makeText(getContext(), "摄像头开启失败", Toast.LENGTH_SHORT).show();        }    };    public static CameraFragment newInstance() {        return new CameraFragment();    }    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,                             Bundle savedInstanceState) {        View root = inflater.inflate(R.layout.camera_frag, container, false);        initVIew(root);        initListener();        return root;    }    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);    }    @Override    public void onResume() {        super.onResume();    }    /**     * 初始化     */    private void initVIew(View root) {        iv_show = (ImageView) root.findViewById(R.id.iv_show_camera2);        //mSurfaceView        mSurfaceView = (SurfaceView) root.findViewById(R.id.surface_view_camera2);        mCatture = (ImageView) root.findViewById(R.id.capture);        mSurfaceHolder = mSurfaceView.getHolder();        mSurfaceHolder.setKeepScreenOn(true);        // mSurfaceView添加回调        mSurfaceHolder.addCallback(new SurfaceHolder.Callback() {            @Override            public void surfaceCreated(SurfaceHolder holder) { //SurfaceView创建                // 初始化Camera                initCamera2();            }            @Override            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {            }            @Override            public void surfaceDestroyed(SurfaceHolder holder) { //SurfaceView销毁                // 释放Camera资源                if (null != mCameraDevice) {                    mCameraDevice.close();                    CameraFragment.this.mCameraDevice = null;                }            }        });    }    /**     * 初始化Camera2     */    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)    private void initCamera2() {        HandlerThread handlerThread = new HandlerThread("Camera2");        handlerThread.start();        childHandler = new Handler(handlerThread.getLooper());        mainHandler = new Handler(getMainLooper());        mCameraID = "" + CameraCharacteristics.LENS_FACING_FRONT;//后摄像头        mImageReader = ImageReader.newInstance(1080, 1920, ImageFormat.JPEG, 1);        mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() { //可以在这里处理拍照得到的临时照片 例如，写入本地            @Override            public void onImageAvailable(ImageReader reader) {                //mCameraDevice.close();                // 拿到拍照照片数据                Image image = reader.acquireNextImage();                ByteBuffer buffer = image.getPlanes()[0].getBuffer();                byte[] bytes = new byte[buffer.remaining()];                buffer.get(bytes);//由缓冲区存入字节数组                final Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);                if (bitmap != null) {                    iv_show.setImageBitmap(bitmap);                }            }        }, mainHandler);        //获取摄像头管理        mCameraManager = (CameraManager) getContext().getSystemService(Context.CAMERA_SERVICE);        try {            if (ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {                //申请WRITE_EXTERNAL_STORAGE权限                requestPermissions(new String[]{Manifest.permission.CAMERA},                        REQUEST_CAMERA_CODE);                //return;            } else {                //打开摄像头                mCameraManager.openCamera(mCameraID, stateCallback, mainHandler);            }        } catch (CameraAccessException e) {            e.printStackTrace();        }    }    @Override    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {        super.onRequestPermissionsResult(requestCode, permissions, grantResults);        if (requestCode == REQUEST_CAMERA_CODE) {            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {                // Permission Granted                try {                    mCameraManager.openCamera(mCameraID, stateCallback, mainHandler);                } catch (CameraAccessException e) {                    e.printStackTrace();                } catch (SecurityException e) {                    e.printStackTrace();                }            } else {                // Permission Denied            }        }    }    /**     * 开始预览     */    private void takePreview() {        try {            // 创建预览需要的CaptureRequest.Builder            final CaptureRequest.Builder previewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);            // 将SurfaceView的surface作为CaptureRequest.Builder的目标            previewRequestBuilder.addTarget(mSurfaceHolder.getSurface());            // 创建CameraCaptureSession，该对象负责管理处理预览请求和拍照请求            mCameraDevice.createCaptureSession(Arrays.asList(mSurfaceHolder.getSurface(), mImageReader.getSurface()), new CameraCaptureSession.StateCallback() // ③            {                @Override                public void onConfigured(CameraCaptureSession cameraCaptureSession) {                    if (null == mCameraDevice) return;                    // 当摄像头已经准备好时，开始显示预览                    mCameraCaptureSession = cameraCaptureSession;                    try {                        // 自动对焦                        previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);                        // 打开闪光灯                        previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);                        // 显示预览                        CaptureRequest previewRequest = previewRequestBuilder.build();                        mCameraCaptureSession.setRepeatingRequest(previewRequest, null, childHandler);                    } catch (CameraAccessException e) {                        e.printStackTrace();                    }                }                @Override                public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {                    Toast.makeText(getContext(), "配置失败", Toast.LENGTH_SHORT).show();                }            }, childHandler);        } catch (CameraAccessException e) {            e.printStackTrace();        }    }    /**     * 拍照     */    private void takePicture() {        if (mCameraDevice == null) return;        // 创建拍照需要的CaptureRequest.Builder        final CaptureRequest.Builder captureRequestBuilder;        try {            captureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);            // 将imageReader的surface作为CaptureRequest.Builder的目标            captureRequestBuilder.addTarget(mImageReader.getSurface());            // 自动对焦            captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);            // 自动曝光            captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);            // 获取手机方向            int rotation = getActivity().getWindowManager().getDefaultDisplay().getRotation();            // 根据设备方向计算设置照片的方向            captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));            //拍照            CaptureRequest mCaptureRequest = captureRequestBuilder.build();            mCameraCaptureSession.capture(mCaptureRequest, null, childHandler);        } catch (CameraAccessException e) {            e.printStackTrace();        }    }    private void initListener() {        mCatture.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                takePicture();            }        });    }}

布局文件：

<?xml version="1.0" encoding="utf-8"?>

源代码地址：https://github.com/gengqifu/361Camera。欢迎fork/star

Android(安卓)Camera2拍照（一）——使用SurfaceView

Camera2 API简介

Camera2的简单使用（使用SurfaceView）

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