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问NoSuchFieldError:使用tess4j的maven项目的RESOURCE_PREFIX
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Stack Overflow用户

提问于 2015-02-03 20:18:35

回答 4查看 3.4K关注 0票数 2

tess4j是一个包含本机库的OCR，我做了一个maven项目来测试它，我确实在eclipse中添加了maven的安装路径。我添加了M2_HOME、MAVEN_HOME和JAVA_HOME环境变量，

这是我的父母pom

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>fr.mssb.ongoing</groupId>
    <artifactId>ongoing-parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0</version>
    <name>ongoing</name>

    <modules>
        <module>capcha-solver</module>
    </modules>

    <build>
        <pluginManagement>
            <plugins>
                <!-- All project will be interpreted (source) and compiled (target) in java 7 -->
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>1.7</source>
                        <target>1.7</target>
                    </configuration>
                </plugin>
                <!-- this will make eclipse:eclipse goal work and make the project Eclipse compatible -->
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-eclipse-plugin</artifactId>
                    <version>2.5.1</version>
                    <configuration>
                        <downloadSources>true</downloadSources>
                        <downloadJavadocs>true</downloadJavadocs>
                        <classpathContainers>
                            <classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7</classpathContainer>
                        </classpathContainers>
                        <additionalBuildcommands>
                            <buildcommand>net.sf.eclipsecs.core.CheckstyleBuilder</buildcommand>
                        </additionalBuildcommands>
                        <additionalProjectnatures>
                            <projectnature>net.sf.eclipsecs.core.CheckstyleNature</projectnature>
                        </additionalProjectnatures>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>

    <!-- All child pom will inherit those dependancies -->
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

这是我的孩子pom

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>fr.mssb.ongoing</groupId>
        <artifactId>ongoing-parent</artifactId>
        <version>1.0</version>
    </parent>

    <groupId>fr.mssb.ongoing</groupId>
    <artifactId>capcha-solver</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging> <!-- I think this is useless -->

    <name>A capcha solver based on terassec ocr</name>

    <build>
        <plugins>
            <!-- autorun unit tests during maven compilation -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <argLine>-Xmx1024m -XX:MaxPermSize=256m -XX:-UseSplitVerifier</argLine>
                    <skipTests>-DskipTests</skipTests>
                </configuration>
            </plugin>

            <!--  this should make the tesseract ocr native dll work without doing anything -->
            <plugin>
                <groupId>com.googlecode.mavennatives</groupId>
                <artifactId>maven-nativedependencies-plugin</artifactId>
                <version>0.0.7</version>
                <executions>
                    <execution>
                        <id>unpacknatives</id>
                        <goals>
                            <goal>copy</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <!-- 
        Log4j 2 is broken up in an API and an implementation (core), where the API 
        provides the interface that applications should code to. Strictly speaking 
        Log4j core is only needed at runtime and not at compile time.
        However, below we list Log4j core as a compile time dependency to improve 
        the startup time for custom plugins. 
        -->
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.1</version>
        </dependency>
        <!--
        Integration of tesseract OCR
        -->
        <dependency>
            <groupId>net.sourceforge.tess4j</groupId>
            <artifactId>tess4j</artifactId>
            <version>1.4.1</version>
        </dependency>
    </dependencies>

</project>

当然，还有代码(取自tess4j示例)

package test;

import java.io.File;

import net.sourceforge.tess4j.Tesseract;
import net.sourceforge.tess4j.TesseractException;

/**
 * Classe d'exemple.
 */
public class TesseractExample {

    public static void main(String[] args) {
        File imageFile = new File("C:\\DEV\\repo\\ongoing\\capcha-solver\\src\\test\\resources\\random.jpg");
        Tesseract instance = Tesseract.getInstance();  // JNA Interface Mapping
        // Tesseract1 instance = new Tesseract1(); // JNA Direct Mapping

        try {
            String result = instance.doOCR(imageFile);
            System.out.println(result);
        } catch (TesseractException e) {
            System.err.println(e.getMessage());
        }
    }
}

当我启动它的时候，我得到了这个异常

Exception in thread "main" java.lang.NoSuchFieldError: RESOURCE_PREFIX
    at net.sourceforge.tess4j.util.LoadLibs.<clinit>(LoadLibs.java:60)
    at net.sourceforge.tess4j.TessAPI.<clinit>(TessAPI.java:40)
    at net.sourceforge.tess4j.Tesseract.init(Tesseract.java:303)
    at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:239)
    at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:188)
    at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:172)
    at test.TesseractExample.main(TesseractExample.java:19)

我不知道这是与tess4j相关的问题还是JNA/JNI的问题，正如你所看到的，我有一个“应该”(以前从未使用过DLL)使它们工作的插件。

另外，在父pom中，我的插件是插件管理标签，我想我应该把它们放在构建标签之间，不是吗？

有什么想法吗？

谢谢。

tesseract

jna

tess4j

maven

java-native-interface

回答 4

Stack Overflow用户

发布于 2015-02-04 18:02:58

有两个问题

1/必须将tess4j中的一些dlls和文件复制到项目根目录

2/ tess4j对com.sun.jna:jna:jar:3.0.9有一个传递依赖，与net.java.dev.jna:jna:jar:4.1.0 (也来自tess4j)冲突包括3.0.9版本使一切正常，RESSOURCE_PREFIX错误来自于此

对于32位版本的pom.xml (您需要安装32位JVM )，如果您想在64位中使用它，请将win32-x86更改为win32-x86-64

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>fr.mssb.ocr</groupId>
    <artifactId>tesseractOcr</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>

    <name>tesseract ocr project</name>

    <build>
        <plugins>
            <!--  
            this extract the 32 bits dll and the tesseractdata folder to 
            the project root from tess4j.jar  
            -->
            <plugin>
                <groupId>org.apache.portals.jetspeed-2</groupId>
                <artifactId>jetspeed-unpack-maven-plugin</artifactId>
                <version>2.2.2</version>
                <dependencies>
                    <dependency>
                      <groupId>net.sourceforge.tess4j</groupId>
                      <artifactId>tess4j</artifactId>
                      <version>1.4.1</version>
                    </dependency>
                </dependencies>
                <executions>
                    <execution>
                        <id>unpack-step</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>unpack</goal>
                        </goals>
                        <configuration>
                            <unpack>
                                <artifact>net.sourceforge.tess4j:tess4j:jar</artifact>
                                <overwrite>true</overwrite>
                                <resources combine.children="append">
                                    <resource>
                                        <path>win32-x86</path>
                                        <destination>../</destination>
                                        <overwrite>true</overwrite>
                                        <flat>true</flat>
                                        <include>*</include>
                                    </resource>
                                    <resource>
                                        <path>tessdata</path>
                                        <destination>../tessdata</destination>
                                        <overwrite>true</overwrite>
                                        <flat>true</flat>
                                        <include>*</include>
                                    </resource>
                                    <resource>
                                        <path>tessdata/configs</path>
                                        <destination>../tessdata/configs</destination>
                                        <overwrite>true</overwrite>
                                        <flat>true</flat>
                                        <include>*</include>
                                    </resource>
                                </resources>
                            </unpack>
                            <verbose>true</verbose>
                        </configuration>
                        </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>net.sourceforge.tess4j</groupId>
            <artifactId>tess4j</artifactId>
            <version>1.4.1</version>
              <exclusions>
                <exclusion>
                    <groupId>com.sun.jna</groupId>
                    <artifactId>jna</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

</project>

票数 1

Stack Overflow用户

发布于 2015-02-06 11:34:46

子pom可以很容易地构建，没有任何问题和手动复制库，这与TESS4J无关。无论如何，如果不再需要JNA3.0.9，可以将其删除：https://github.com/nguyenq/tess4j/issues/8

不过，要运行tess4j，您需要做的只是maven依赖：

<dependency>
    <groupId>net.sourceforge.tess4j</groupId>
    <artifactId>tess4j</artifactId>
    <version>1.4.1</version>
</dependency>

以及TESS4J-API的正确使用，例如：

File imageFile = new File("C:\\random.png");
Tesseract instance = Tesseract.getInstance();

//In case you don't have your own tessdata, let it also be extracted for you
File tessDataFolder = LoadLibs.extractTessResources("tessdata");

//Set the tessdata path
instance.setDatapath(tessDataFolder.getAbsolutePath());

    try {
        String result = instance.doOCR(imageFile);
        System.out.println(result);
    } catch (TesseractException e) {
        System.err.println(e.getMessage());
    }

就这样!

票数 1

Stack Overflow用户

发布于 2015-08-04 06:10:04

这个问题是由net.java.dev.jna:jna和com.sun.jna:jna之间的冲突引起的。这两个jars都包含一个com.sun.jna.Platform类。这两个jars都声明为tess4j依赖项。要解决这个问题，可以省略pom中的第二个依赖项：

<dependency>
    <groupId>net.sourceforge.tess4j</groupId>
    <artifactId>tess4j</artifactId>
    <version>1.4.1</version>
    <exclusions>
        <exclusion>
            <groupId>com.sun.jna</groupId>
            <artifactId>jna</artifactId>
        </exclusion>
    </exclusions>
</dependency>

票数 1

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/28307976

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