Tess4J error after distributing as war NoClassDefF

问题:

I have Spring boot Webserver project which works ok in my PC under Intellij IDEA, but it not works after distributing to the same PC as war file - NoClassDefFoundError: Could not initialize class net.sourceforge.tess4j.TessAPI.

my code:

ITesseract instance = new Tesseract(); // JNA Interface Mapping

 instance.setDatapath(new File(datapath).getPath()); 
 instance.setLanguage("eng");      
 try {
          String result = instance.doOCR(imageFile); 
 } catch (TesseractException e) {
          System.err.println(e.getMessage());
 }

I have only one maven dependency, releted to Tess4J:

<dependency>
        <groupId>net.sourceforge.tess4j</groupId>
        <artifactId>tess4j</artifactId>
        <version>3.0.0</version>
</dependency>

I've got the error after running my distributed war:

There was an unexpected error (type=Internal Server Error, status=500).
Could not initialize class net.sourceforge.tess4j.TessAPI

Full Tomcat log:

java.lang.NoClassDefFoundError: Could not initialize class net.sourceforge.tess4j.TessAPI
        at net.sourceforge.tess4j.Tesseract.init(Tesseract.java:367) ~[tess4j-3.0.0.jar:3.0.0]
        at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:280) ~[tess4j-3.0.0.jar:3.0.0]
        at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:212) ~[tess4j-3.0.0.jar:3.0.0]
        at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:196) ~[tess4j-3.0.0.jar:3.0.0]
        at ocr.OCRController.handleFileUpload(OCRController.java:127) ~[classes/:0.3.0]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_51]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_51]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_51]
        at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_51]
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]

How can I fix the error? I have the plan to host this app in Windows Azure under Tomcat. Thank you for any help, friends!

回答1:

The problem was in temp folder - it does not contain all necessary dlls.

Info for community: 1. Check temp folder under tomact - for me the path to it is: D:\Programs_Files\apache-tomcat-8.0.27\temp

This temp folder MUST contain the directory tess4j\win32-x86-64 with next 3 files: gsdll64.dll, liblept171.dll, libtesseract304.dll (or your version)

I had my problem because the directory tess4j\win32-x86-64 have never been created in temp.

BUT

My app works ok under Intellij IDEA because another Temp folder (for IDEA) works ok - C:\Users\Iuliia\AppData\Local\Temp\

contains tess4j\win32-x86-64\gsdll64.dll, tess4j\win32-x86-64\liblept171.dll, tess4j\win32-x86-64\libtesseract304.dll as expected.

Note, that this files are created in process of calling Tesseract in your code. Not early.

HOW I FIX THE PROBLEM with temp under Tomcat

I've added win32-x86-64\gsdll64.dll, win32-x86-64\liblept171.dll, win32-x86-64\libtesseract304.dll to the resources directory in my project.

Look at my project structure:

After deploying to tomcat, the necessary dlls is under classes directory (important!) - it means they are is in the scope.

Now it will be added to

D:\Programs_Files\apache-tomcat-8.0.27\temp\tess4j\win32-x86-64 as expected.

回答2:

Another fix for the NoClassDefFoundError is e.g. installing the respective Microsoft C++ Runtime (scroll to the bottom and expand Other Tools and Frameworks):

Since the DLLs are built using Visual Studio 2015/2017, please ensure you have Visual C++ 2015 Redistributable or VC++ 2017 Redistributable installed.

Refer to the Tess4J development tutorial for more details.

回答3:

I upgraded to Windows 10 and all of a sudden tessarct no longer worked for my app.

As per the Tess4J docs, you need to have VC++ 2017 Redistributable installed.

After I installed it on Windows 10, it all worked fine again.

If you've upgraded to Windows 10, and you are having the above problem, and it worked before, then this is likely your issue.