java.lang.ClassNotFoundException: org.apache.commo

I am trying to compile UploadServlet servlet via apache tomcat 8.0.14. my web.xml is fine andUploadServlet.java has compiled properly but yet when try to run i get following error

ERROR

HTTP Status 500 - Error instantiating servlet class UploadServlet

exception
javax.servlet.ServletException: Error instantiating servlet class UploadServlet

root cause
java.lang.NoClassDefFoundError: org/apache/commons/fileupload/FileItemFactory

root cause
java.lang.ClassNotFoundException: org.apache.commons.fileupload.FileItemFactory

UploadServlet.java

import java.io.*;
import java.util.*;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.output.*;

public class UploadServlet extends HttpServlet {

   private boolean isMultipart;
   private String filePath;
   private int maxFileSize = 50 * 1024;
   private int maxMemSize = 4 * 1024;
   private File file ;

   public void init( ){

      filePath =  getServletContext().getInitParameter("file-upload"); 
   }
   public void doPost(HttpServletRequest request, 
               HttpServletResponse response)
              throws ServletException, java.io.IOException {

      isMultipart = ServletFileUpload.isMultipartContent(request);
      response.setContentType("text/html");
      java.io.PrintWriter out = response.getWriter( );
      if( !isMultipart ){
         out.println("<html>");
         out.println("<head>");
         out.println("<title>Servlet upload</title>");  
         out.println("</head>");
         out.println("<body>");
         out.println("<p>No file uploaded</p>"); 
         out.println("</body>");
         out.println("</html>");
         return;
      }

      DiskFileItemFactory factory = new DiskFileItemFactory();

      factory.setSizeThreshold(maxMemSize);

      factory.setRepository(new File("C:\\apache-tomcat-8.0.14\\temp"));


      ServletFileUpload upload = new ServletFileUpload(factory);

      upload.setSizeMax( maxFileSize );

      try{ 

      List fileItems = upload.parseRequest(request);

      Iterator i = fileItems.iterator();

      out.println("<html>");
      out.println("<head>");
      out.println("<title>Servlet upload</title>");  
      out.println("</head>");
      out.println("<body>");
      while ( i.hasNext () ) 
      {
         FileItem fi = (FileItem)i.next();
         if ( !fi.isFormField () )  
         {

            String fieldName = fi.getFieldName();
            String fileName = fi.getName();
            String contentType = fi.getContentType();
            boolean isInMemory = fi.isInMemory();
            long sizeInBytes = fi.getSize();
            System.out.println(fileName);

            if( fileName.lastIndexOf("\\") >= 0 )
            {
               file = new File( filePath + 
               fileName.substring(fileName.lastIndexOf("\\"))) ;
            }
            else
            {
               file = new File( filePath + 
               fileName.substring(fileName.lastIndexOf("\\")+1)) ;
            }
            fi.write( file ) ;
            out.println("Uploaded Filename: " + fileName + "<br>");
         }
      }
      out.println("</body>");
      out.println("</html>");
   }catch(Exception ex) {
       System.out.println(ex);
   }
   }
   public void doGet(HttpServletRequest request, 
                       HttpServletResponse response)
        throws ServletException, java.io.IOException {

        throw new ServletException("GET method used with " +
                getClass( ).getName( )+": POST method required.");
   } 
}

回答1:

You need to put commons-fileupload.jar and commons-io.jar to your WEB-INF/lib forlder. Classpath is used during build, but they must be available during runtime also.

Actually, if you had used IDE for Java EE development (like Eclipse) putting these Jars to WEB-INF/lib would be enough, as they would be automatically visible in the claspath for build.

回答2:

as @Gas , I forgot to add .jar file in WEB-INF/lib folder. and then the issue resolved.