java.lang.NoClassDefFoundError：com / itextpdf / text / DocumentException

Question

我正在尝试通过以下servlet生成动态PDF文件。

import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
// Document Object
import com.itextpdf.text.Document;
//For adding content into PDF document
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.PdfWriter;
import com.itextpdf.text.DocumentException;

public class CreatePDFExample extends HttpServlet {

    //invoked from doGet method to create PDF through servlet 
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //Set content type to application / pdf
    //browser will open the document only if this is set
    response.setContentType("application/pdf");
    //Get the output stream for writing PDF object        
    OutputStream out=response.getOutputStream();
    try {
        Document document = new Document();
        /* Basic PDF Creation inside servlet */
        PdfWriter.getInstance(document, out);
        document.open();
        document.add(new Paragraph("Tutorial to Generate PDF using Servlet"));
        document.add(new Paragraph("PDF Created Using Servlet, iText Example Works"));
        document.close();
    }
            catch (DocumentException exc){
            throw new IOException(exc.getMessage());
            }
    finally {            
        out.close();
    }
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}

@Override
public String getServletInfo() {
    return "This Servlet Generates PDF Using iText Library";
}
}

但我收到以下错误：

Error 500--Internal Server Error

java.lang.NoClassDefFoundError: com/itextpdf/text/DocumentException
at CreatePDFExample.processRequest(CreatePDFExample.java:24)
at CreatePDFExample.doPost(CreatePDFExample.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1053)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:387)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:305)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6310)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:317)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3622)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2569)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)

我正在使用 weblogic应用程序服务器8.1 ....我正在使用 iTextPDF 。所以我已经为jar文件设置了CLASSPATH。

CLASSPATH:
D:\itextpdf-5.3.4.jar;D:\servlet-2-3.jar;.;

PATH:
C:\Program Files (x86)\Java\jdk1.6.0_14\bin;.;

请告诉我为什么会出现此错误？???我已经花了很多时间。没有遇到小问题。请帮助我。

谢谢

完成建议的操作后，出现以下错误

 Error 500--Internal Server Error

 java.lang.ExceptionInInitializerError
at com.itextpdf.text.pdf.PdfWriter.(PdfWriter.java:1403)
at CreatePDFExample.processRequest(CreatePDFExample.java:26)
at CreatePDFExample.doPost(CreatePDFExample.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1053)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:387)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:305)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6310)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:317)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3622)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2569)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)
 Caused by: java.lang.NullPointerException
at java.lang.Class.privateGetDeclaredFields(Class.java:1488)
at java.lang.Class.getDeclaredFields(Class.java:1073)

Answer 1

先前的答案告诉您，缺少了一个jar，这不是一个不好的猜测，因为错误消息清楚地表明找不到iText类之一。

不幸的是，该错误消息具有误导性。Java还表示，如果存在任何歧义，它将找不到类。如果您的CLASSPATH中有多个iText jar，就是这种情况。

通过在CLASSPATH中添加另一个iText
jar，使问题变得更糟。现在，您遇到了一个问题，该问题是由weblogic实例中的JVM提供两个不同版本的iText引起的。

搜索所有CLASSPATH，不要忘记服务器CLASSPATH，您会发现D：\
itextpdf-5.3.4.jar并不是weblogic寻找PdfWriter类的唯一地方。从CLASSPATH中删除所有iText
jar，直到只剩下一个。