出现错误：java.lang.UnsatisfiedLinkError：本机库C：\\ opencv \\ build \\ java \\ x64 \\ opencv_java300.dll

Question

I am running a servlet program to read an image using opencv,
getting error :

java.lang.UnsatisfiedLinkError: Native Library C:\opencv\build\java\x64\opencv_java300.dll already loaded in another classloader . When restarting the IDE it works fine.

I loaded System.loadLibrary ( Core.NATIVE_LIBRARY_NAME ) ; in servlet only ones.

Can anybody suggest a solution for how to unload it. And also anybody know how to read an image from browser using opencv in java.?

Answer 1

It is because the library is not in the system path, it needs to first added to the system path, then load. First extract the OpenCV to C drive something like this c:\\opencv\\... then use this code below to during initializing, it will automatically load the OpenCV lib in windows environment.

public static void loadOpenCV_Lib() throws Exception {
    String model = System.getProperty("sun.arch.data.model");
    String libraryPath = "C:/opencv/build/java/x86/";
    if(model.equals("64")) {
        libraryPath = "C:/opencv/build/java/x64/";
    }
    System.setProperty("java.library.path", libraryPath);
    Field sysPath = ClassLoader.class.getDeclaredField("sys_paths");
    sysPath.setAccessible(true);
    sysPath.set(null, null);
    System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
}

And also it will automatically detect the system model and load the lib according to the system model.