Issue with the libtesseract303.dll in netbeans

问题:

I am implementing an OCR system. When I placed dll files on the java class path it gives the following error.

Exception in thread "main" java.lang.UnsatisfiedLinkError: G:\software\apache-tomcat-8.0.18-windows-x64\apache-tomcat-8.0.18\bin\win32-x86-64\libtesseract303.dll: Can't find dependent libraries

And after running the project if I check the java class path, all the dll files added are vanished. I followed almost all the tutorials related to tesseract. But can't find a solution. Does anybody have an idea?

1).JDK version- 1.8(64 bit) 2).Library is 64 bit 3).all three libraries are placed within library path. 4) I followed the steps given by this tutorial here.In this tutorial they have introduced the 32 bit libraries.Instead of that I used 64 bit libraries.I got the follwing error java.lang.UnsatisfiedLinkError: Unable to load library 'libtesseract304': Native library (win32-x86-64/libtesseract303.dll) not found in resource path ([file:/C:/Users/User/Documents/GitHub/Linguist/build/web/WEB-INF/classes). Then I tried to check if i can load the library using system.load(). Then I got the following error. My class path is placed with tomcat folder.

Exception in thread "main" java.lang.UnsatisfiedLinkError: G:\software\apache-tomcat-8.0.18-windows-x64\apache-tomcat-8.0.18\bin\win32-x86-64\libtesseract303.dll: Can't find dependent libraries

回答1:

Find below a small working example application. From there you could start to investigate and pick the parts you need.

Assuming the following structure and files

pom.xml
sample.gif
src/main/java/sub/optimal/tess4j/Demo.java
tessdata/eng.traineddata

pom.xml

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>sub.optimal</groupId>
    <artifactId>Tess4JDemo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.shade.version>2.3</maven.shade.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>net.sourceforge.tess4j</groupId>
            <artifactId>tess4j</artifactId>
            <version>3.0.0</version>
            <type>jar</type>
        </dependency>
        <dependency>
            <groupId>org.ghost4j</groupId>
            <artifactId>ghost4j</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>${maven.shade.version}</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.4.0</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>java</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <mainClass>sub.optimal.tess4j.Demo</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

sample.gif

src/main/java/sub/optimal/tess4j/Demo.java

package sub.optimal.tess4j;
import java.io.File;
import net.sourceforge.tess4j.Tesseract;
import net.sourceforge.tess4j.TesseractException;
public class Demo {
    public static void main(String[] args) {
        File imageFile = new File("sample.gif");
        Tesseract instance = new Tesseract();
        try {
            String result = instance.doOCR(imageFile);
            System.out.println(result);
        } catch (TesseractException e) {
            e.printStackTrace(System.err);
        }
    }
}

tessdata/eng.traineddata was downloaded from https://tesseract-ocr.googlecode.com/files/eng.traineddata.gz (don't forget to uncompress the file)

Running this small example with mvn exec:java produce the following output

[INFO] --- exec-maven-plugin:1.4.0:java (default-cli) @ Tess4JDemo ---
Hello OCR!