怎么用Android Camera实现最简单的预览框显示

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Android要预览Camer2界面比Camera1稍微复杂一点，但是也是不难的，下面是简单的预览相关代码。

首先要再AndroidManifest.xml中添加权限

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

创建一个xml包含控件TextureView

比如activity_main.xml：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="Http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <TextureView        android:id="@+id/textureView"        android:layout_width="match_parent"        android:layout_height="match_parent" />    <Button        android:id="@+id/btnStop"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_margin="0.8dp"        android:text="stop preview"        android:layout_alignParentBottom="true"        android:layout_alignParentEnd="true"/>    <Button        android:id="@+id/btnStart"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_margin="0.8dp"        android:text="start preview"        android:layout_alignParentBottom="true"        android:layout_toStartOf="@id/btnStop"/></RelativeLayout>

在Activity创建使用 CamaerManager

(1)使用 CamaerManager.openCamera(),传入监听openState状态
(2)在openState状态里面执行预览界面即可
(3)关闭预览框的时候释放一下对象就行
比如下面的MainActivity2.java代码：

package com.lwz.camera;import java.util.ArrayList;import java.util.Arrays;import java.util.Collections;import java.util.Comparator;import java.util.List;import android.Manifest;import android.content.Context;import android.content.pm.PackageManager;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.CaptureFailure;import android.hardware.camera2.CaptureRequest;import android.hardware.camera2.CaptureResult;import android.hardware.camera2.TotalCaptureResult;import android.hardware.camera2.params.StreamConfigurationMap;import android.os.Bundle;import android.util.Log;import android.util.Size;import android.view.Surface;import android.view.TextureView;import android.view.View;import android.widget.Button;import android.widget.Toast;import androidx.annotation.NonNull;import androidx.appcompat.app.AppCompatActivity;import androidx.core.content.ContextCompat;public class MainActivity2 extends AppCompatActivity implements View.OnClickListener {    private static final String TAG = "Camera2Test";    private static final int REQUEST_CAMERA_PERMISSION = 80;    private TextureView mTextureView;    private Button mBtnStart;    private Button mBtnStop;    private CameraManager mCameraManager;    private CameraDevice mCameraDevice;    private String mCameraId = "0";    private Size previewSize; // 用于设置预览的宽高    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        Log.e(TAG, "onCreate！");        setContentView(R.layout.activity_main);        initData();        intiView();        initEvent();    }    private void intiView() {        mTextureView = (TextureView) findViewById(R.id.textureView);        mBtnStart = (Button) findViewById(R.id.btnStart);        mBtnStop = (Button) findViewById(R.id.btnStop);    }    private void initData() {        mCameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);        if (mCameraManager == null) {            Toast.makeText(this, "获取不到CameraService对象！", Toast.LENGTH_LONG).show();            finish();        }    }    private void initEvent() {        mBtnStart.setOnClickListener(this);        mBtnStop.setOnClickListener(this);        // 对预览View的状态监听        mTextureView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {            @Override            public void onSurfaceTextureAvailable(@NonNull SurfaceTexture surface, int width, int height) {                Log.i(TAG, "onSurfaceTextureAvailable width = " + width + ",height = " + height);                //1、当SurefaceTexture可用的时候，设置相机参数并打开相机                initCamera();            }            @Override            public void onSurfaceTextureSizeChanged(@NonNull SurfaceTexture surface, int width, int height) {                Log.i(TAG, "onSurfaceTextureSizeChanged width = " + width + ",height = " + height);            }            @Override            public boolean onSurfaceTextureDestroyed(@NonNull SurfaceTexture surface) {                Log.i(TAG, "onSurfaceTextureDestroyed！");                return false;            }            @Override            public void onSurfaceTextureUpdated(@NonNull SurfaceTexture surface) {                //正常预览的时候，会一直打印                //Log.i(TAG, "onSurfaceTextureUpdated！");            }        });    }    private void initCamera() {        Log.i(TAG, "initCamera");        // 2.配置前置相机，获取尺寸及id        getCameraIdAndPreviewSizeByFacing(CameraCharacteristics.LENS_FACING_FRONT); // 0为前置摄像头,Camera api1里面定义0为后置        // 3.打开相机        openCamera();    }        private void getCameraIdAndPreviewSizeByFacing(int lensFacingFront) {        Log.i(TAG, "getCameraIdAndPreviewSizeByFacing");        try {            String[] cameraIdList = mCameraManager.getCameraIdList(); //如果设备节点不可用，会阻塞在这里            Log.i(TAG, "getCameraIdAndPreviewSizeByFacing cameraIdList = " + Arrays.toString(cameraIdList));            for (String cameraId : cameraIdList) {                CameraCharacteristics cameraCharacteristics = mCameraManager.getCameraCharacteristics(cameraId);                int deviceLevel = cameraCharacteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL); //硬件与api2的契合度，0-4                Log.i(TAG, "deviceLevel = " + deviceLevel);                int facing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING);                if (facing != lensFacingFront) {                    continue;                }                StreamConfigurationMap streamConfigurationMap = cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);                Size[] outputSizes = streamConfigurationMap.getOutputSizes(SurfaceTexture.class);                mCameraId = cameraId;                previewSize = setOptimalPreviewSize(outputSizes, mTextureView.getMeasuredWidth(), mTextureView.getMeasuredHeight());                Log.i(TAG, "最佳预览尺寸（w-h）：" + previewSize.getWidth() + "-" + previewSize.getHeight() + ",相机id：" + mCameraId);            }        } catch (CameraAccessException e) {            Log.e(TAG, "getCameraIdAndPreviewSizeByFacing error = " + e.getMessage());        }    }        private void openCamera() {        try {            // 4.权限检查            if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)                    != PackageManager.PERMISSION_GRANTED) {                requestCameraPermission();                return;            }            // 5.真正打开相机            Log.i(TAG, "openCamera");            mCameraManager.openCamera(mCameraId, mStateCallback, null);        } catch (CameraAccessException e) {            Log.e(TAG, "openCamera error = " + e.getMessage());        }    }    //请求相机权限    private void requestCameraPermission() {        requestPermissions(new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);    }        private Size setOptimalPreviewSize(Size[] sizes, int previewViewWidth, int previewViewHeight) {        List<Size> bigEnoughSizes = new ArrayList<>();        List<Size> notBigEnoughSizes = new ArrayList<>();        for (Size size : sizes) {            if (size.getWidth() >= previewViewWidth && size.getHeight() >= previewViewHeight) {                bigEnoughSizes.add(size);            } else {                notBigEnoughSizes.add(size);            }        }        if (bigEnoughSizes.size() > 0) {            return Collections.min(bigEnoughSizes, new Comparator<Size>() {                @Override                public int compare(Size lhs, Size rhs) {                    return Long.signum((long) lhs.getWidth() * lhs.getHeight() -                            (long) rhs.getWidth() * rhs.getHeight());                }            });        } else if (notBigEnoughSizes.size() > 0) {            return Collections.max(notBigEnoughSizes, new Comparator<Size>() {                @Override                public int compare(Size lhs, Size rhs) {                    return Long.signum((long) lhs.getWidth() * lhs.getHeight() -                            (long) rhs.getWidth() * rhs.getHeight());                }            });        } else {            Log.e(TAG, "未找到合适的预览尺寸");            return sizes[0];        }    }    //关闭相机，释放对象    private void releaseCamera() {        if (mCameraDevice != null) {            mCameraDevice.close();            mCameraDevice = null;        }    }        private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {        @Override        public void onOpened(CameraDevice camera) {            Log.i(TAG, "StateCallback！ onOpened");            mCameraDevice = camera; // 打开成功，保存代表相机的CameraDevice实例            SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();            surfaceTexture.setDefaultBufferSize(mTextureView.getWidth(), mTextureView.getHeight());            Surface surface = new Surface(surfaceTexture);            ArrayList<Surface> previewList = new ArrayList<>();            previewList.add(surface);            try {                // 6.将TextureView的surface传递给CameraDevice                mCameraDevice.createCaptureSession(previewList, new CameraCaptureSession.StateCallback() {                    @Override                    public void onConfigured(@NonNull CameraCaptureSession session) {                        try {                            CaptureRequest.Builder builder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);                            builder.addTarget(surface); // 必须设置才能正常预览                            CaptureRequest captureRequest = builder.build();                            // 7.CameraCaptureSession与CaptureRequest绑定（这是最后一步，已可显示相机预览）                            session.setRepeatingRequest(captureRequest, mSessionCaptureCallback, null);                        } catch (CameraAccessException e) {                            Log.e(TAG, "createCaptureRequest error = " + e.getMessage());                        }                    }                    @Override                    public void onConfigureFailed(@NonNull CameraCaptureSession session) {                        Log.e(TAG, "onConfigureFailed");                    }                }, null);            } catch (CameraAccessException e) {                Log.e(TAG, "createCaptureSession error = " + e.getMessage());            }        }        @Override        public void onDisconnected(@NonNull CameraDevice camera) {            Log.e(TAG, "StateCallback！ onDisconnected camera.getId() = " + camera.getId());            releaseCamera();        }        @Override        public void onError(@NonNull CameraDevice camera, int error) {            Log.e(TAG, "StateCallback camera.getId() = " + camera.getId() + " , error = " + error);            releaseCamera();        }    };    //预览情况回调    private CameraCaptureSession.CaptureCallback mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {        @Override        public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {            super.onCaptureStarted(session, request, timestamp, frameNumber);            // 正常预览会一直刷新            //Log.i(TAG, "mSessionCaptureCallback onCaptureStarted frameNumber =" + frameNumber);        }        @Override        public void onCaptureProgressed(CameraCaptureSession session, CaptureRequest request, CaptureResult partialResult) {            super.onCaptureProgressed(session, request, partialResult);            Log.i(TAG, "mSessionCaptureCallback onCaptureProgressed request =" + request);        }        @Override        public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {            super.onCaptureFailed(session, request, failure);            Log.e(TAG, "mSessionCaptureCallback onCaptureFailed request =" + request);        }        @Override        public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {            super.onCaptureCompleted(session, request, result);            // 正常预览时会一直刷新            //Log.i(TAG, "mSessionCaptureCallback onCaptureCompleted request =" + request);        }    };    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.btnStart:                Log.i(TAG, "btnStart！");                openCamera();                break;            case R.id.btnStop:                Log.i(TAG, "btnStop！");                releaseCamera();                break;            default:        }    }    @Override    protected void onDestroy() {        super.onDestroy();        releaseCamera();    }}

Camera1的使用更简单，但是Camera1新增功能会少一点。

Camaera1的简单使用：Android Camera1实现预览框显示

“怎么用Android Camera实现最简单的预览框显示”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识可以关注编程网网站，小编将为大家输出更多高质量的实用文章！