学习使用kotlin编程语言, 进行opencv计算机视觉开发
- macOS Catalina 10.15.7
- 2.4 GHz 四核Intel Core i5
- Java 8
openjdk version "1.8.0_292" OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_292-b10) OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.292-b10, mixed mode)
- Python 2.7.16
- OpenCV 4.5.5
- IntelliJ IDEA 2021.3 (Ultimate Edition)
- 安装homebrew
- homebrew 安装sdkman, 进行Java JDK版本管理
sdk list java, 选择JDK 8进行安装 - macOS终端执行
xcode-select install, 安装Xcode或Xcode Command Line Tools 成功，则GCC ready - homebrew 安装cmake
brew install cmake - homebrew 安装ant
brew install ant, 编译java 包需要 - 接下来，使用opencv源码进行编译并生成Java 8版本的jar包， 注意，采用
brew install opencv的方式安装是不支持Java版本的， 采用brew install --build-from-source opencv的方式openCV 会安装至/usr/local/Cellar/opencv/x.x.x/下, 此目录下包含需要的 jar包和 dylib库文件. 此方案编译后的Java 类文件版本较新, 因此运行Java开发程序的时候推荐使用最新JDK版本运行, 否则会出现以下问题. 若需要打包分发Java开发程序, 那么，最好编译为较旧版本(即，采用源码编译的方式). JDK11不能允许Java开发程序, 我们通过sdkman 切换至较新JDK17版本后, 即可成功运行
/Users/tinytinycn/.sdkman/candidates/java/11.0.2-open/bin/java -Djava.library.path=/usr/local/Cellar/opencv/4.5.4_1/share/java/opencv4 -javaagent:/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=54635:/Applications/IntelliJ IDEA.app/Contents/bin -Dfile.encoding=UTF-8 -classpath /Users/tinytinycn/IdeaProjects/learn-java-opencv/out/production/learn-java-opencv:/usr/local/Cellar/opencv/4.5.4_1/share/java/opencv4/opencv-454.jar com.company.Main
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/opencv/core/Core has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at com.company.Main.main(Main.java:16)
- 安装git
- 创建源码下载目录,
mkdir ~/your_opencv_project - 进入源码下载目录
cd ~/your_opencv_project下载源码,git clone https://github.com/opencv/opencv.git( 按个人实际需要是否下载opencv_contrib的源码) - 创建编译目录,
mkdir build - 进入编译目录,
cd build - 创建安装目录,
mkdir /user/local/Cellar/opencv_jdk8 - 编译检查
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF -DCMAKE_INSTALL_PREFIX=/usr/local/Cellar/opencv_jdk8 ../
-- Java:
-- ant: /usr/local/bin/ant (ver 1.10.11)
-- JNI: /Library/Java/JavaVirtualMachines/jdk1.8.0_251.jdk/Contents/Home/include /Library/Java/JavaVirtualMachines/jdk1.8.0_251.jdk/Contents/Home/include/darwin /Library/Java/JavaVirtualMachines/jdk1.8.0_251.jdk/Contents/Home/include
-- Java wrappers: YES
-- Java tests: YES
--
-- Install to: /usr/local
-- ------------
-- Configuring done
-- Generating done
- 检查相关依赖是否安装， 确保ant,JNI,Java wrappers等环境变量正常
- 执行
make -j8进行编译, 等待编译结束 - 编译成功100%后, 执行
make install, 进行安装 - java 8 版本的opencv jar 和依赖库安装至
/usr/local/Cellar/opencv_jdk8/share/java/opencv4/ - 创建Kotlin 项目，在IntelliJ IDEA 中配置项目模块依赖, 让编辑器可以找到jar所在的位置
- 配置VM option
-Djava.library.path=/usr/local/Cellar/opencv_jdk8/share/java/opencv4/,让编译器可以找到动态库所在的位置 - kotlin代码中 需要加载Java 库文件
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);- 在External Libraries 中可以查看opencv-455.jar 的 META-INF/MANIFEST.MF, 可以发现编译java版本为 1.8
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.10.12
Created-By: 1.8.0_292-b10 (AdoptOpenJDK)
Specification-Title: OpenCV
Specification-Version: 4.5.5-pre
Implementation-Title: OpenCV
Implementation-Version: 4.5.4-347-g9777fbacf6
Implementation-Date: 星期五 十二月 24 2021 11:40:16 CST