本篇内容介绍了“怎么用Android Camera实现最简单的预览框显示”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
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！
