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現在Android智能手機的像素都會提供照相的功能，大部分的手機的攝像頭的像素都在1000萬以上的像素，有的甚至會更高。它們大多都會支持光學變焦、曝光以及快門等等。
下面的程序Demo實例示范了使用Camera v2來進行拍照，當用戶按下拍照鍵時，該應用會自動對焦，當對焦成功時拍下照片。
layout/activity_main.xml界面布局代碼如下：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.fukaimei.camerav2test">
<!-- 授予該程序使用攝像頭的權限 -->
<uses-permission android:name="android.permission.CAMERA" />
<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/AppTheme">
<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>
上面的程序的界面提供了一個自定義TextureView來顯示預覽取景，十分簡單。該自定義TextureView類的代碼如下：
AutoFitTextureView.java邏輯代碼如下：
package com.fukaimei.camerav2test;
import android.content.Context;
import android.util.AttributeSet;
import android.view.TextureView;
/**
* Created by FuKaimei on 2017/9/29.
*/
public class AutoFitTextureView extends TextureView {
private int mRatioWidth = 0;
private int mRatioHeight = 0;
public AutoFitTextureView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setAspectRatio(int width, int height) {
mRatioWidth = width;
mRatioHeight = height;
requestLayout();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
if (0 == mRatioWidth || 0 == mRatioHeight) {
setMeasuredDimension(width, height);
} else {
if (width < height * mRatioWidth / mRatioHeight) {
setMeasuredDimension(width, width * mRatioHeight / mRatioWidth);
} else {
setMeasuredDimension(height * mRatioWidth / mRatioHeight, height);
}
}
}
}
接來了的MainActivity.java程序將會使用CameraManager來打開CameraDevice，并通過CameraDevice創建CameraCaptureSession，然后即可通過CameraCaptureSession進行預覽或拍照了。
MainActivity.java邏輯代碼如下：
package com.fukaimei.camerav2test;
import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.graphics.ImageFormat;
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.CameraMetadata;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.Image;
import android.media.ImageReader;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v4.app.ActivityCompat;
import android.util.Log;
import android.util.Size;
import android.util.SparseIntArray;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.widget.Toast;
import java.io.File;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
public class MainActivity extends Activity implements View.OnClickListener {
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final String TAG = "MainActivity";
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 AutoFitTextureView textureView;
// 攝像頭ID（通常0代表后置攝像頭，1代表前置攝像頭）
private String mCameraId = "0";
// 定義代表攝像頭的成員變量
private CameraDevice cameraDevice;
// 預覽尺寸
private Size previewSize;
private CaptureRequest.Builder previewRequestBuilder;
// 定義用于預覽照片的捕獲請求
private CaptureRequest previewRequest;
// 定義CameraCaptureSession成員變量
private CameraCaptureSession captureSession;
private ImageReader imageReader;
private final TextureView.SurfaceTextureListener mSurfaceTextureListener
= new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture texture
, int width, int height) {
// 當TextureView可用時，打開攝像頭
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture texture
, int width, int height) {
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture texture) {
}
};
private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
// 攝像頭被打開時激發該方法
@Override
public void onOpened(CameraDevice cameraDevice) {
MainActivity.this.cameraDevice = cameraDevice;
// 開始預覽
createCameraPreviewSession(); // ②
}
// 攝像頭斷開連接時激發該方法
@Override
public void onDisconnected(CameraDevice cameraDevice) {
cameraDevice.close();
MainActivity.this.cameraDevice = null;
}
// 打開攝像頭出現錯誤時激發該方法
@Override
public void onError(CameraDevice cameraDevice, int error) {
cameraDevice.close();
MainActivity.this.cameraDevice = null;
MainActivity.this.finish();
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textureView = (AutoFitTextureView) findViewById(R.id.texture);
// 為該組件設置監聽器
textureView.setSurfaceTextureListener(mSurfaceTextureListener);
findViewById(R.id.capture).setOnClickListener(this);
}
@Override
public void onClick(View view) {
captureStillPicture();
}
private void captureStillPicture() {
try {
if (cameraDevice == null) {
return;
}
// 創建作為拍照的CaptureRequest.Builder
final CaptureRequest.Builder captureRequestBuilder =
cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
// 將imageReader的surface作為CaptureRequest.Builder的目標
captureRequestBuilder.addTarget(imageReader.getSurface());
// 設置自動對焦模式
captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// 設置自動曝光模式
captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 獲取設備方向
int rotation = getWindowManager().getDefaultDisplay().getRotation();
// 根據設備方向計算設置照片的方向
captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION
, ORIENTATIONS.get(rotation));
// 停止連續取景
captureSession.stopRepeating();
// 捕獲靜態圖像
captureSession.capture(captureRequestBuilder.build()
, new CameraCaptureSession.CaptureCallback() // ⑤
{
// 拍照完成時激發該方法
@Override
public void onCaptureCompleted(CameraCaptureSession session
, CaptureRequest request, TotalCaptureResult result) {
try {
// 重設自動對焦模式
previewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
// 設置自動曝光模式
previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 打開連續取景模式
captureSession.setRepeatingRequest(previewRequest, null,
null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
// 打開攝像頭
private void openCamera(int width, int height) {
setUpCameraOutputs(width, height);
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
// 打開攝像頭
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
manager.openCamera(mCameraId, stateCallback, null); // ①
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void createCameraPreviewSession() {
try {
SurfaceTexture texture = textureView.getSurfaceTexture();
texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());
Surface surface = new Surface(texture);
// 創建作為預覽的CaptureRequest.Builder
previewRequestBuilder = cameraDevice
.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
// 將textureView的surface作為CaptureRequest.Builder的目標
previewRequestBuilder.addTarget(new Surface(texture));
// 創建CameraCaptureSession，該對象負責管理處理預覽請求和拍照請求
cameraDevice.createCaptureSession(Arrays.asList(surface
, imageReader.getSurface()), new CameraCaptureSession.StateCallback() // ③
{
@Override
public void onConfigured(CameraCaptureSession cameraCaptureSession) {
// 如果攝像頭為null，直接結束方法
if (null == cameraDevice) {
return;
}
// 當攝像頭已經準備好時，開始顯示預覽
captureSession = cameraCaptureSession;
try {
// 設置自動對焦模式
previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// 設置自動曝光模式
previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
// 開始顯示相機預覽
previewRequest = previewRequestBuilder.build();
// 設置預覽時連續捕獲圖像數據
captureSession.setRepeatingRequest(previewRequest,
null, null); // ④
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {
Toast.makeText(MainActivity.this, "配置失敗！"
, Toast.LENGTH_SHORT).show();
}
}, null
);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void setUpCameraOutputs(int width, int height) {
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
// 獲取指定攝像頭的特性
CameraCharacteristics characteristics
= manager.getCameraCharacteristics(mCameraId);
// 獲取攝像頭支持的配置屬性
StreamConfigurationMap map = characteristics.get(
CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
// 獲取攝像頭支持的最大尺寸
Size largest = Collections.max(
Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
new CompareSizesByArea());
// 創建一個ImageReader對象，用于獲取攝像頭的圖像數據
imageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
ImageFormat.JPEG, 2);
imageReader.setOnImageAvailableListener(
new ImageReader.OnImageAvailableListener() {
// 當照片數據可用時激發該方法
@Override
public void onImageAvailable(ImageReader reader) {
// 獲取捕獲的照片數據
Image image = reader.acquireNextImage();
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
// 使用IO流將照片寫入指定文件
File file = new File(getExternalFilesDir(null), "pic.jpg");
buffer.get(bytes);
try (
FileOutputStream output = new FileOutputStream(file)) {
output.write(bytes);
Toast.makeText(MainActivity.this, "保存: " + file, Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
} finally {
image.close();
}
}
}, null);
// 獲取最佳的預覽尺寸
previewSize = chooseOptimalSize(map.getOutputSizes(
SurfaceTexture.class), width, height, largest);
// 根據選中的預覽尺寸來調整預覽組件（TextureView的）的長寬比
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
textureView.setAspectRatio(
previewSize.getWidth(), previewSize.getHeight());
} else {
textureView.setAspectRatio(
previewSize.getHeight(), previewSize.getWidth());
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
Log.d(TAG, "出現錯誤");
}
}
private static Size chooseOptimalSize(Size[] choices
, int width, int height, Size aspectRatio) {
// 收集攝像頭支持的打過預覽Surface的分辨率
List<Size> bigEnough = new ArrayList<>();
int w = aspectRatio.getWidth();
int h = aspectRatio.getHeight();
for (Size option : choices) {
if (option.getHeight() == option.getWidth() * h / w &&
option.getWidth() >= width && option.getHeight() >= height) {
bigEnough.add(option);
}
}
// 如果找到多個預覽尺寸，獲取其中面積最小的。
if (bigEnough.size() > 0) {
return Collections.min(bigEnough, new CompareSizesByArea());
} else {
System.out.println("找不到合適的預覽尺寸！！！");
return choices[0];
}
}
// 為Size定義一個比較器Comparator
static class CompareSizesByArea implements Comparator<Size> {
@Override
public int compare(Size lhs, Size rhs) {
// 強轉為long保證不會發生溢出
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
}
}
上面的程序中序號①的代碼是用于打開系統攝像頭，openCamera()方法的第一個參數代表請求打開的攝像頭ID，此處傳入的攝像頭ID為“0”，這代表打開設備后置攝像頭；如果需要打開設備指定攝像頭（比如前置攝像頭），可以在調用openCamera()方法時傳入相應的攝像頭ID。
注意：由于該程序需要使用手機的攝像頭，因此還需要在清單文件AndroidManifest.xml文件中授權相應的權限：
<!-- 授予該程序使用攝像頭的權限 --> <uses-permission android:name="android.permission.CAMERA" />
Demo程序運行效果界面截圖如下：
Demo程序源碼下載地址
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持億速云。
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