当Autodetect解析器似乎工作正常时,为什么Tika的ForkParser抛出NoClassDefFoundError？

Question

我正在使用apache Tika 1.0.使用ForkParser,每当我解析pdf文件时,我得到以下NoClassDefFoundException:

java.lang.NoClassDefFoundError: org/apache/tika/fork/MemoryURLStreamHandler$Record
    at org.apache.tika.fork.MemoryURLStreamHandler.createURL(MemoryURLStreamHandler.java:46)
    at org.apache.tika.fork.ClassLoaderProxy.findResource(ClassLoaderProxy.java:73)
    at java.lang.ClassLoader.getResource(ClassLoader.java:977)
    at org.apache.log4j.helpers.Loader.getResource(Loader.java:96)
    at org.apache.log4j.LogManager.<clinit>(LogManager.java:105)
    at org.apache.log4j.Logger.getLogger(Logger.java:104)
    at org.apache.commons.logging.impl.Log4JLogger.getLogger(Log4JLogger.java:289)
    at org.apache.commons.logging.impl.Log4JLogger.<init>(Log4JLogger.java:109)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at org.apache.commons.logging.impl.LogFactoryImpl.createLogFromClass(LogFactoryImpl.java:1116)
    at org.apache.commons.logging.impl.LogFactoryImpl.discoverLogImplementation(LogFactoryImpl.java:914)
    at org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:604)
    at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:336)
    at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:310)
    at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
    at org.apache.pdfbox.pdfparser.BaseParser.<clinit>(BaseParser.java:58)
    at org.apache.pdfbox.pdmodel.PDDocument.load(PDDocument.java:1087)
    at org.apache.pdfbox.pdmodel.PDDocument.load(PDDocument.java:1053)
    at org.apache.tika.parser.pdf.PDFParser.parse(PDFParser.java:80)
    at org.apache.tika.parser.CompositeParser.parse(CompositeParser.java:242)
    at org.apache.tika.parser.CompositeParser.parse(CompositeParser.java:242)
    at org.apache.tika.parser.AutoDetectParser.parse(AutoDetectParser.java:120)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.tika.fork.ForkServer.call(ForkServer.java:136)
    at org.apache.tika.fork.ForkServer.processRequests(ForkServer.java:116)
    at org.apache.tika.fork.ForkServer.main(ForkServer.java:64)

检查jar表明在tika-core jar文件中存在MemoryURLStreamHandler $ Record.当我使用AutoDetectParser而不是ForkParser时,我能够从文件中提取元数据而没有任何问题,但需要能够约束Tika内存使用,因此我需要使用ForkParser.如何获得pdf解析与Tika的ForkParser一起使用？

这是一段代码片段,直到解析的地方:

public static FileAnalysis analyze(File f) throws java.io.FileNotFoundException{

    FileInputStream     fis             = null;
    ToXMLContentHandler contentHandler  = new ToXMLContentHandler();
    Metadata            metadata        = new Metadata();
    ParseContext        context         = new ParseContext();
    ForkParser          parser          = new ForkParser();

    parser.setJavaCommand(props.getProperty("forkJavaCommand", "java") + " " +
                          props.getProperty("forkJavaMemory", "-Xmx64m"));

    parser.setPoolSize(1);

    fis = new FileInputStream(f);
    try {
        parser.parse(fis, contentHandler, metadata, context);
    } catch (Throwable e) {
        logger.error("Exception while analyzing file\n" +
        "CAUTION: metadata may still have useful content in it!\n" +
        "Exception:\n" + e, e);
    }

编辑#1

我使用"-f"选项测试了Tika 1.0和Tika 0.10 CLI应用程序,并在使用SoyLatte java 6端口用于Mac OS-X时接收到IOException(Broken Pipe).该端口仅在我的开发机器上运行,因此我使用"-f"开关在linux测试机器上运行CLI应用程序(1.0和0.10),如下所示

java -jar tika-app-1.0.jar -f /path/to/my/file.pdf

我不再收到异常,但我也没有得到任何输出.我发现这很奇怪,但认为它可能仍在工作,只是没有产生任何输出(永远是乐观主义者,我猜).

我在我的Mac OS-X终端中解除了所有环境变量的设置,并尝试使用OS-X内置的java 6运行Tika CLI.我得到了与linux测试机相同的结果,打印了一些新行,但是没有其他的.我尝试了一个jpg文件而不是pdf文件,tika应用程序打印出xhtml文档,其中包含所宣传的元数据!我接下来尝试了一个docx文件,但是像pdfs一样,不打印任何东西.

编辑#2

我写了一个小的测试java程序,并将它放在我们的应用程序的上下文之外,以便它在一个新的环境中运行.

import java.io.File;
import java.io.FileInputStream;

import org.apache.tika.parser.ParseContext;
import org.apache.tika.fork.ForkParser;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.sax.ToXMLContentHandler;

import org.apache.tika.Tika;

public class ForkParserTest {

    public static void main(String[] args) {

        if (args.length != 1) {
            System.out.println("must be passed the file to be parsed as the first argument");
            return;
        }

        try {
            File f = new File(args[0]);

            FileInputStream     fis             = null;
            ToXMLContentHandler contentHandler  = new ToXMLContentHandler();
            Metadata            metadata        = new Metadata();
            ParseContext        context         = new ParseContext();
            ForkParser          parser          = new ForkParser();

            fis = new FileInputStream(f);

            parser.parse(fis, contentHandler, metadata, context);

            System.out.println(contentHandler.toString());

        } catch (Exception e) { 
            System.out.println("Exception caught in main"); 
            e.printStackTrace();
        }

        return;
    }
}

我这样编译它

javac -cp /path/to/tika-app-1.0.jar ForkParserTest.java

并且这样跑

java -cp /path/to/tika-app-1.0.jar:${PWD} ForkParserTest /path/to/file.pdf

并用jpeg测试它.它的性能与Tika CLI应用程序完全相同,它为jpg打印XHTML文档,但不为pdf或docx文件打印任何内容.

如果有人知道如何解决这个问题,请告诉我!此外,如果您对pdf文件或docx文件运行此测试并实际获得打印结果,请告诉我您是如何做到的.

谢谢!

我也是相当新的发布在stackoverflow,如果这是完全tl;博士,反馈是赞赏,给我建议如何使这更简洁.