android camera

布局
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/content_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="40dp"
    android:paddingLeft="0dp"
    android:paddingRight="0dp"
    android:paddingTop="0dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.admin.smartcam.main.MainActivity"
    tools:showIn="@layout/app_bar_main">
<FrameLayout
    android:id="@+id/camera_FrameLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</FrameLayout>


</RelativeLayout>

1、在android4.0以下的版本支持【 android.hardware.Camera】api

2、其使用很简单

代码如下：

这个类用于返回一个camera
package com.admin.smartcam.androidcamera.camera;

/**
 * Created by Admin on 2017/4/27 0027.
 * android4.0以下版本使用
 */

public class MinForCamera {
    private static int cameraBackOrFront = 0;

    private MinForCamera() {
    }

    public void setCamera(int cameraBackOrFront) {
        this.cameraBackOrFront = cameraBackOrFront;
    }


    private static android.hardware.Camera camera = android.hardware.Camera.open(cameraBackOrFront); // attempt to get a Camera instance

    public static android.hardware.Camera getCamera() {
        return camera; // returns null if camera is unavailable
    }
}

在MainActivity.java中调用：
    public void initScreen() {
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);// 设置全屏
        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);//设置高亮
    }
    @RequiresApi(api = Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    private void startView() {
        if (checkCameraHardware(this) == true) {       //检测相机硬件
            final Camera mCamera = MinForCamera.getCamera();//获得系统摄像机
            showCamera = new ShowCamera(MainActivity.this, mCamera);
            FrameLayout preview = (FrameLayout) findViewById(R.id.camera_FrameLayout);
            preview.addView(showCamera);

        }
    }
    /**
     * 检查摄像机是否可用
     *
     * @param context
     * @return
     */
    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;
        }
    }

我使用的是SurfaceView作为显示载体
package com.admin.smartcam.androidcamera.camera;

import android.content.Context;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Toast;

import java.lang.reflect.Method;
import java.util.Objects;
import java.util.Timer;
import java.util.TimerTask;
/**
 * 自定义相机显示
 * Created by Admin on 2017/1/31.
 */

@RequiresApi(api = Build.VERSION_CODES.ICE_CREAM_SANDWICH)
public class ShowCamera extends SurfaceView implements SurfaceHolder.Callback, Camera.AutoFocusCallback, View.OnClickListener, Camera.FaceDetectionListener {
    private SurfaceHolder hold;
    private Camera theCamera;
    private Context context;
    private Paint paint = null;
    Camera.Parameters parameters;

    @RequiresApi(api = Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    public ShowCamera(Context context, Camera camera) {
        super(context);
        this.theCamera = camera;
        this.context = context;
        if (cameranumber() <= 0)      //没有可用相机
        {
            Toast.makeText(context, "未检测到可用相机", Toast.LENGTH_SHORT).show();
        } else {
           // videoMed = new VideoMed();  //录制视屏
            hold = getHolder();
            hold.addCallback(this);
            hold.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        }

    }

    /**
     * 返回所有可用相机总数
     * @return
     */
    public int cameranumber() {
        return theCamera.getNumberOfCameras();//得到所有可用相机的总数
    }

    @RequiresApi(api = Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    @Override
    public void surfaceCreated(SurfaceHolder surfaceHolder) {
        if (Integer.parseInt(Build.VERSION.SDK) >= 15) {
            initCamera(); //相机参数的初始化设置
            hold.addCallback(this); // holder加入回调接口
            // setType必须设置，要不出错.
            hold.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

            TimerTask task = new TimerTask() {
                @Override
                public void run() {
                    //videoMed.StopWriteVideo();
                }
            };
            Timer timer = new Timer();
            timer.scheduleAtFixedRate(task, 0, 1000);
        } else {
            setDispaly(parameters, theCamera); //控制图像正常显示
            theCamera.cancelAutoFocus();      //如果要实现连续的自动对焦，这一句必须加上

        }

    }

    /**
     * 预览发生改变
     *
     * @param surfaceHolder
     * @param i
     * @param i1
     * @param i2
     */
    @Override
    public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
        if (surfaceHolder.getSurface() == null) {
            // 预览不存在
            return;
        }
        // stop preview before making changes
        try {
            if (parameters.getMaxNumDetectedFaces() > 0)  //检测设备是否支持人脸识别
                {
                    theCamera.stopFaceDetection();
                }
            theCamera.stopPreview();
            //theCamera.setPreviewCallback(null);
            //theCamera.release();//释放资源
        } catch (Exception e) {
            Log.d("<<<相机改变>>>", "调整出错！+"+i+">>i1<<"+i1+">>12<<"+i2);
        }

        // 在这里做任何调整,旋转或重新格式化变化
        try {
                theCamera.setPreviewDisplay(surfaceHolder);
                surfaceHolder.setFixedSize(i,i1);
                theCamera.startPreview();
                //设置人脸识别监听
                if (parameters.getMaxNumDetectedFaces() > 0) {  //检测设备是否支持人脸识别
                    Log.d("启动人脸检测》》","正在启动！");
                    theCamera.startFaceDetection();//启动人脸检测相机需要在startPreview()之后
                    theCamera.setFaceDetectionListener(ShowCamera.this);
                }
        } catch (Exception e) {
            Log.d("相机改变:>>", "相机改变，调整出错！"+i+">>i1<<"+i1+">>12<<"+i2);
        }
    }

    /**
     * 预览结束，关闭相应资源
     * @param surfaceHolder
     */
    @Override
    public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
        if (theCamera != null) {
            try {
                Log.d("相机销毁:>>", "相机销毁！"+theCamera);
                //parameters.notify();
                theCamera.stopFaceDetection();
                //theCamera.setPreviewCallback(null);
                theCamera.stopPreview();
                //theCamera.setPreviewCallbackWithBuffer(null);
                theCamera.release();
                theCamera = null;
                Log.d("相机销毁:>>", "相机销毁成功！"+theCamera);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 实现自动对焦
     *
     * @param b
     * @param camera
     */
    @Override
    public void onAutoFocus(boolean b, Camera camera) {
        if (b) {
            camera.cancelAutoFocus();//自动对焦。
        }
    }

    //相机参数的初始化设置
    @RequiresApi(api = Build.VERSION_CODES.ICE_CREAM_SANDWICH)
    private void initCamera() {
        if (theCamera != null) {
            Log.d("初始化相机","相机："+theCamera);
            parameters = theCamera.getParameters();
            parameters.setPictureFormat(PixelFormat.JPEG);
            parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF); //不开启闪光灯 FLASH_MODE_ON//开启闪光灯
            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);//1连续对焦
            theCamera.setParameters(parameters);
            setDispaly(parameters, theCamera);
            theCamera.cancelAutoFocus();//如果要实现连续的自动对焦，这一句必须加上
            //设置人脸识别监听
            if (parameters.getMaxNumDetectedFaces() > 0) synchronized (Objects.class){  //检测设备是否支持人脸识别
                theCamera.startPreview();
                Log.d("启动人脸检测》》","正在启动！");
                //theCamera.startFaceDetection();//启动人脸检测相机需要在startPreview()之后
                //theCamera.setFaceDetectionListener(ShowCamera.this);
            } else
                //Toast.makeText(context, "你的设备不支持人脸识别", Toast.LENGTH_SHORT).show();
                theCamera.startPreview();
        }
    }

    //控制图像的正确显示方向
    private void setDispaly(Camera.Parameters parameters, Camera camera) {
        if (Integer.parseInt(Build.VERSION.SDK) >= 8) {
            setDisplayOrientation(camera, 90);
        } else {
            parameters.setRotation(90);
        }
    }

    //实现的图像的正确显示
    private void setDisplayOrientation(Camera camera, int i) {
        Method downPolymorphic;
        try {
            downPolymorphic = camera.getClass().getMethod("setDisplayOrientation", new Class[]{int.class});
            if (downPolymorphic != null) {
                downPolymorphic.invoke(camera, new Object[]{i});
            }
        } catch (Exception e) {
            Log.e("图像出错+Camera:", "图像出错!");
        }
    }

    @Override
    public void onClick(View view) {
        if (view != null) {
            Toast.makeText(context, "单击事件" + view, Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onFaceDetection(Camera.Face[] faces, Camera camera) {
        if (faces.length > 0) {
            for (Camera.Face face : faces) {
                {
                    Log.d("人脸", "检测到人脸坐标为: " + face.rect.centerX() * 1.1f +
                            "
 检测到人脸坐标为：Y :  " + face.rect.centerY() * 1.1f);
                }
            }
//
//            VideoMed video = new VideoMed();//录制视屏
//            video.StopWriteVideo();
//            new EmailToUser("1928654615@qq.com", "主人：检测到监控范围内有人出现！").start();
        }
    }
    private void timeTack()
    {
        Log.d("启动人脸检测》》","正在启动*******！");
        new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(1500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.d("启动人脸检测》》","正在启动！");
                theCamera.startFaceDetection();//启动人脸检测相机需要在startPreview()之后
                theCamera.setFaceDetectionListener(ShowCamera.this);
                Log.d("启动人脸检测》》","启动成功！");
            }

        }.run();
        //ScheduledExecutorService service = Executors.newSingleThreadScheduledExecutor();
        //service.scheduleAtFixedRate(runnable,2,0, TimeUnit.SECONDS);
    }
    private void facetimeTack() {
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                try {
                    Thread.sleep(1500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                theCamera.startFaceDetection();//启动人脸检测相机需要在startPreview()之后
                theCamera.setFaceDetectionListener(ShowCamera.this);
            }
        };
        //new Timer().scheduleAtFixedRate(task,1500,5000000);

    }
}

记得加权限：  
  <uses-permission android:name="android.permission.CAMERA" />

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