Tess4J error after distributing as war NoClassDefFoundError: Could not initialize class net.sourceforge.tess4j.TessAPI

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.