Android是谷歌领导的开放手机联盟开发的基于linux的开源移动操作系统。详细信息请参见Android主页。
Android平台的开发与其他平台的开发有很大的不同。所以，在开始为Android编程之前，我们建议你确保你熟悉以下关键主题:
Java编程语言，是Android操作系统的主要开发技术。此外，你可以发现Oracle文档对Java很有用。
Java Native Interface (JNI)是一种在Java虚拟机中运行本机代码的技术。此外，您还可以发现关于JNI的Oracle文档非常有用。
Android Activity和它的生命周期，这是一个基本的Android API类。
OpenCV的开发当然需要对Android摄像头有一定的了解。

android studio缓存目录更改配置

1.下载opencv
https://opencv.org/releases/
2.最好使用JDK，最好不要使用android studio自带jrd，目前JDK版本不能超过15，推荐使用JDK15，我直接用的openjdk
3.加入opencv模块，方法如下，
我试图直接导入opencv到android studio，next按钮为灰色，所以只能使用这种方法。

// Add module into Android Studio application project:
//
// - Android Studio way:
//   (will copy almost all OpenCV Android SDK into your project, ~200Mb)
//
//   Import module: Menu -> "File" -> "New" -> "Module" -> "Import Gradle project":
//   Source directory: select this "sdk" directory
//   Module name: ":opencv"
//
// - or attach library module from OpenCV Android SDK
//   (without copying into application project directory, allow to share the same module between projects)
//
//   Edit "settings.gradle" and add these lines:
//
//   def opencvsdk='<path_to_opencv_android_sdk_rootdir>'
//   // You can put declaration above into gradle.properties file instead (including file in HOME directory),
//   // but without 'def' and apostrophe symbols ('): opencvsdk=<path_to_opencv_android_sdk_rootdir>
//   include ':opencv'
//   project(':opencv').projectDir = new File(opencvsdk + '/sdk')
//
//
//
// Add dependency into application module:
//
// - Android Studio way:
//   "Open Module Settings" (F4) -> "Dependencies" tab
//
// - or add "project(':opencv')" dependency into app/build.gradle:
//
//   dependencies {
//       implementation fileTree(dir: 'libs', include: ['*.jar'])
//       ...
//       implementation project(':opencv')
//   }
//
//
//
// Load OpenCV native library before using:
//
// - avoid using of "OpenCVLoader.initAsync()" approach - it is deprecated
//   It may load library with different version (from OpenCV Android Manager, which is installed separatelly on device)
//
// - use "System.loadLibrary("opencv_java4")" or "OpenCVLoader.initDebug()"
//   TODO: Add accurate API to load OpenCV native library
//
//
//
// Native C++ support (necessary to use OpenCV in native code of application only):
//
// - Use find_package() in app/CMakeLists.txt:
//
//   find_package(OpenCV 3.4 REQUIRED java)
//   ...
//   target_link_libraries(native-lib ${OpenCV_LIBRARIES})
//
// - Add "OpenCV_DIR" and enable C++ exceptions/RTTI support via app/build.gradle
//   Documentation about CMake options: https://developer.android.com/ndk/guides/cmake.html
//
//   defaultConfig {
//       ...
//       externalNativeBuild {
//           cmake {
//               cppFlags "-std=c++11 -frtti -fexceptions"
//               arguments "-DOpenCV_DIR=" + opencvsdk + "/sdk/native/jni" // , "-DANDROID_ARM_NEON=TRUE"
//           }
//       }
//   }
//
// - (optional) Limit/filter ABIs to build ('android' scope of 'app/build.gradle'):
//   Useful information: https://developer.android.com/studio/build/gradle-tips.html (Configure separate APKs per ABI)
//
//   splits {
//       abi {
//           enable true
//           universalApk false
//           reset()
//           include 'armeabi-v7a' // , 'x86', 'x86_64', 'arm64-v8a'
//       }
//   }
//