there are few examples involving Java.
after introducing lib and DLL according to online operations, an error Java is reported Lang.unsatisfiedlinkerror
Someone said they would add system loadLibrary(Core.NATIVE_LIBRARY_NAME); Otherwise, it will report an error java Lang.unsatisfiedlinkerror
but it still report error: java.lang.UnsatisfiedLinkError

Solution: (my operating system is windows64 bit)
Copy the downloaded dll file under opencv\build\java\x64 to C:\Windows\System32


then go to idea to start the main method, and there will be no errors.