UnsatisfiedLinkError - 无法加载库 - 在资源路径中找不到本机库

Question

I have the following error at runtime, while trying to run Tess4J:

Exception in thread "main" java.lang.UnsatisfiedLinkError: Unable to load library 'libtesseract302': Native library (win32-x86-64/libtesseract302.dll) not found in resource path ([myproject/target/classes/, ...some jars...])

My questions are:

1) What exactly it tries to find and where?

2) Why is it apparently searches for myproject/target/classes/ directory? I set it nowhere.

3) Why is it ignores "native directory path" I set for tess4j.jar in user library descripto in Eclipse? My DLLs are there. If it didn't ignore the path, it would find DLLs.

4) Why is it apparently prepending DLL name with win32-x86-64/ ? I set this nowhere. Is this standard prefix of some API?

5) What is "resource path"? How to set it?

Answer 1

Like the error says, it's looking for win32-x86-64/libtesseract302.dll in java.class.path . Part of your classpath apparently includes myproject/target/classes .

The prefix represents the platform and architecture of the shared library to be loaded, which allows shared libraries for different targets to be included in the same archive. If JNA cannot find the requested library name in the system load path, then it attempts to find it within your resource path (extracting it, if necessary). So if you put the DLL in a jar file, you'll need to give it the win32-x86-64 prefix in order for it to load.

The "resource path" is nominally your class path; basically anywhere reachable by ClassLoader.getResource() .

Answer 2

The error stems from your trying to load 32-bit DLLs in 64-bit JVM. The possible solution is switch to 32-bit JVM; alternatively, use 64-bit Tesseract and Leptonica DLLs .

Answer 3

Had the same issue, sorted with the following lines

System.load("/usr/local/lib/liblept.so.5")
System.loadLibrary("tesseract")

For your case, it might be different libraries but in the end is pretty much the same: just load the libraries that you need manually.

Answer 4

Why don't you use JNA API http://www.java2s.com/Code/Jar/j/Downloadjna351jar.htm to load native library? Once you putted into your project classpath, you add this code

NativeLibrary.addSearchPath("libtesseract302", "your native lib path"); make sure you have this libtesseract302.dll file, normally it is located at windows32 folder.

For example, if your libtesseract302.dll file in somewhere c:/abcv/aaa/libtesseract302.dll then you just set the path like this NativeLibrary.addSearchPath("libtesseract302", "c:/abcv/aaa");

I don't know how windows path look like either c:/abcv/aaa or c:\\\\abcv\\\\aaa\\\\

if you want easier way, just put all your necessary dll file into your windows32 folder, JVM will take care of it.

Another issue might be you were not installing the application correctly or the application version is unmatch with your jar version. try to install the latest application and download the latest jar to try again. Hope it helps :)

Answer 5

I had the same problem and found that this "resource path" is not set by "native directory path" .
You can however add new folders to it by using "Add External Class Folder" in the Library tab, even if this folder does not contain any class file but native library files(like DLL on Windows)

Answer 6

A few days ago I ran into the same error message when trying to load a C++ DLL with JNA. It turned out that the cause was a missing DLL that my DLL depended on.

In my case it was the MS Visual Studio 2012 redistributable, which I then downloaded and installed on the machine and the problem was gone. Try using Dependency Walker to find any missing libraries and install them.

Answer 7

我遇到了类似的问题，我尝试了上面的所有答案，但它没有解决我的问题，最后我检查了我从哪里得到了dll的源，发现我没有安装windows redistributable 2012，dll是使用它，一旦我安装它，异常就消失了。

Answer 8

I think an easier way to get around this error would be to revert to an earlier version where you were not getting this error. Right click on the project folder and navigate to local history to revert to an earlier version. I verified this workaround on the android studio installed on Mac OS Big sur.