AndroidX是Jetpack包下的组件，谷歌帮你考虑好了很多细节，用就完事了。这些细节想自己设置的话也可以，不设置使用默认值照样很舒服。
导包
implementation "androidx.camera:camera-camera2:1.0.0-beta07"
implementation "androidx.camera:camera-view:1.0.0-alpha14"
implementation "androidx.camera:camera-extensions:1.0.0-alpha14"
implementation "androidx.camera:camera-lifecycle:1.0.0-beta07"
请求权限
在 Manifest 的 manifest 节点下中加入以下内容：
<!--摄像头权限-->
<uses-permission android:name="android.permission.CAMERA" />
<!--具备摄像头-->
<uses-feature android:name="android.hardware.camera.any" />
<!--存储图像或者视频权限-->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<!--录制音频权限-->
<uses-permission android:name="android.permission.RECORD_AUDIO" />
Android Q适配
在 manifest 标签里面加入一条属性：
android:requestLegacyExternalStorage="true"
画黄线不理，如果不加这句，在Android Q上会无法往相册存储文件。
创建预览布局
这里参考官方Demo的写法，最底部图层是一个PreviewView用来预览，上层放两个按钮，一个用来拍照，一个用来录像。
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="@+id/btnStartVideo"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginBottom="50dp"
android:elevation="2dp"
android:scaleType="fitCenter"
android:text="Start Video"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@id/camera_capture_button" />
<Button
android:id="@+id/camera_capture_button"
android:layout_width="100dp"
android:layout_height="100dp"
android:elevation="2dp"
android:scaleType="fitCenter"
android:text="Take Photo"
app:layout_constraintBottom_toBottomOf="@+id/btnStartVideo"
app:layout_constraintEnd_toStartOf="@id/btnStartVideo"
app:layout_constraintStart_toStartOf="parent" />
<androidx.camera.view.PreviewView
android:id="@+id/viewFinder"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
Activity中申请权限
声明权限列表
companion object {
private const val REQUEST_CODE_PERMISSIONS = 10
private val REQUIRED_PERMISSIONS = arrayOf(Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.RECORD_AUDIO)
}
判断当前是否已有权限的方法
private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
ContextCompat.checkSelfPermission(baseContext, it) == PackageManager.PERMISSION_GRANTED
}
在 onCreate 里开始主要逻辑。如果已有权限，开启相机预览。
if (allPermissionsGranted()) {
startCamera()
} else {
ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
}
在请求权限返回的时候，判断是否已有权限，如果有了就可以开启预览了
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
if (requestCode == REQUEST_CODE_PERMISSIONS) {
if (allPermissionsGranted()) {
startCamera()
} else {
Toast.makeText(this, "Permissions not granted by the user.", Toast.LENGTH_SHORT).show()
finish()
}
}
}
声明全局变量
private lateinit var cameraExecutor: ExecutorService
var cameraProvider: ProcessCameraProvider? = null//相机信息
var preview: Preview? = null//预览对象
var cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA//当前相机
var camera: Camera? = null//相机对象
private var imageCapture: ImageCapture? = null//拍照用例
var videoCapture: VideoCapture? = null//录像用例
开启相机预览
开启预览，把预览内容放进 PreviewView 里。
private fun startCamera() {
cameraExecutor = Executors.newSingleThreadExecutor()
val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
cameraProviderFuture.addListener(Runnable {
cameraProvider = cameraProviderFuture.get()//获取相机信息
//预览配置
preview = Preview.Builder()
.build()
.also {
it.setSurfaceProvider(viewFinder.createSurfaceProvider())
}
imageCapture = ImageCapture.Builder().build()//拍照用例配置
val imageAnalyzer = ImageAnalysis.Builder()
.build()
.also {
it.setAnalyzer(cameraExecutor, LuminosityAnalyzer { luma ->
Log.d(TAG, "Average luminosity: $luma")
})
}
cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA//使用后置摄像头
videoCapture = VideoCapture.Builder()//录像用例配置
// .setTargetAspectRatio(AspectRatio.RATIO_16_9) //设置高宽比
// .setTargetRotation(viewFinder.display.rotation)//设置旋转角度
// .setAudioRecordSource(AudioSource.MIC)//设置音频源麦克风
.build()
try {
cameraProvider?.unbindAll()//先解绑所有用例
camera = cameraProvider?.bindToLifecycle(this, cameraSelector, preview, imageCapture, videoCapture)//绑定用例
} catch (exc: Exception) {
Log.e(TAG, "Use case binding failed", exc)
}
}, ContextCompat.getMainExecutor(this))
}
监听，写在Activity外面
typealias LumaListener = (luma: Double) -> Unit
再在Activity里面写一个内部类
private class LuminosityAnalyzer(private val listener: LumaListener) : ImageAnalysis.Analyzer {
private fun ByteBuffer.toByteArray(): ByteArray {
rewind()
val data = ByteArray(remaining())
get(data)
return data
}
override fun analyze(image: ImageProxy) {
val buffer = image.planes[0].buffer
val data = buffer.toByteArray()
val pixels = data.map { it.toInt() and 0xFF }
val luma = pixels.average()
listener(luma)
image.close()
}
}
界面销毁时关闭线程
override fun onDestroy() {
super.onDestroy()
cameraExecutor.shutdown()
}
拍照方法
private fun takePhoto() {
val imageCapture = imageCapture ?: return
val file = File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).path +
"/CameraX" + SimpleDateFormat(FILENAME_FORMAT, Locale.CHINA).format(System.currentTimeMillis()) + ".jpg")
val outputOptions = ImageCapture.OutputFileOptions.Builder(file).build()
imageCapture.takePicture(outputOptions, ContextCompat.getMainExecutor(this),
object : ImageCapture.OnImageSavedCallback {
override fun onError(exc: ImageCaptureException) {
Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
}
override fun onImageSaved(output: ImageCapture.OutputFileResults) {
val savedUri = Uri.fromFile(file)
val msg = "Photo capture succeeded: $savedUri"
Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
Log.d(TAG, msg)
}
})
}
录像方法
private fun takeVideo() {
//视频保存路径
val file = File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).path + "/CameraX" + SimpleDateFormat(
FILENAME_FORMAT, Locale.CHINA
).format(System.currentTimeMillis()) + ".mp4")
//开始录像
videoCapture?.startRecording(file, Executors.newSingleThreadExecutor(), object : OnVideoSavedCallback {
override fun onVideoSaved(@NonNull file: File) {
//保存视频成功回调，会在停止录制时被调用
Toast.makeText(this@MainActivity, file.absolutePath, Toast.LENGTH_SHORT).show()
}
override fun onError(videoCaptureError: Int, message: String, cause: Throwable?) {
//保存失败的回调，可能在开始或结束录制时被调用
Log.e("", "onError: $message")
}
})
btnStartVideo.setOnClickListener {
//结束录像
videoCapture?.stopRecording()//停止录制
preview?.clear()//清除预览
btnStartVideo.text = "Start Video"
btnStartVideo.setOnClickListener {
btnStartVideo.text = "Stop Video"
takeVideo()
}
Toast.makeText(this, file.path, Toast.LENGTH_SHORT).show()
Log.d("path", file.path)
}
}
