如何解决此java.lang.NoClassDefFoundError:org/apache/commons/io/output/DeferredFileOutputStream? [英] How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream?

问题描述

我正在使用以下代码将文件上传到tomcat5.5中，它给了我以下异常

java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream

您能帮我找出来吗?

import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

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.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Servlet implementation class FileUploadServlet
 */
public class FileUploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public FileUploadServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    @SuppressWarnings("rawtypes")
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        boolean isMultipart = ServletFileUpload.isMultipartContent(request);
        System.out.println("Status : "+isMultipart);
        if (isMultipart) {
            FileItemFactory factory = new DiskFileItemFactory();
            ServletFileUpload upload = new ServletFileUpload(factory);

            try {
                List items = upload.parseRequest(request);
                Iterator iterator = items.iterator();
                while (iterator.hasNext()) {
                    FileItem item = (FileItem) iterator.next();

                    if (!item.isFormField()) {
                        String fileName = item.getName();

                        String root = getServletContext().getRealPath("/");
                        File path = new File(root + "/uploads");
                        if (!path.exists()) {
                            boolean status = path.mkdirs();
                        }

                        File uploadedFile = new File(path + "/" + fileName);
                        System.out.println(uploadedFile.getAbsolutePath());
                        item.write(uploadedFile);
                    }
                }
            } catch (FileUploadException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        response.sendRedirect("upload.jsp");
    }

}

这是我使用的commons-fileupload-1.2.2.jar

罐子

解决方案

特定的异常消息告诉您在类路径中缺少所提到的类.正如org.apache.commons.io包名称所暗示的那样，提到的类是 http://commons.apache.org/io 项目的一部分.

确实，Commons FileUpload具有Commons IO作为 dependency .您需要下载，并将commons-io.jar拖放到/WEB-INF/lib中. >

另请参见:

• 如何使用JSP/Servlet将文件上传到服务器?
• 如何添加将JAR库转换为WAR项目，而无需面对java.lang.ClassNotFoundException?类路径vs构建路径vs/WEB-INF/lib
• 如何导入我的Eclipse项目中的javax.servlet API?

I am using the below code to upload a file in to tomcat5.5 and it gives me the following exception

java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream

could you please help me to find it out?

import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

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.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Servlet implementation class FileUploadServlet
 */
public class FileUploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public FileUploadServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    @SuppressWarnings("rawtypes")
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        boolean isMultipart = ServletFileUpload.isMultipartContent(request);
        System.out.println("Status : "+isMultipart);
        if (isMultipart) {
            FileItemFactory factory = new DiskFileItemFactory();
            ServletFileUpload upload = new ServletFileUpload(factory);

            try {
                List items = upload.parseRequest(request);
                Iterator iterator = items.iterator();
                while (iterator.hasNext()) {
                    FileItem item = (FileItem) iterator.next();

                    if (!item.isFormField()) {
                        String fileName = item.getName();

                        String root = getServletContext().getRealPath("/");
                        File path = new File(root + "/uploads");
                        if (!path.exists()) {
                            boolean status = path.mkdirs();
                        }

                        File uploadedFile = new File(path + "/" + fileName);
                        System.out.println(uploadedFile.getAbsolutePath());
                        item.write(uploadedFile);
                    }
                }
            } catch (FileUploadException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        response.sendRedirect("upload.jsp");
    }

}

this is the jar i use commons-fileupload-1.2.2.jar

解决方案

The particular exception message is telling you that the mentioned class is missing in the classpath. As the org.apache.commons.io package name hints, the mentioned class is part of the http://commons.apache.org/io project.

And indeed, Commons FileUpload has Commons IO as a dependency. You need to download and drop commons-io.jar in the /WEB-INF/lib as well.

See also:

• How to upload files to server using JSP/Servlet?
• How to add JAR libraries to WAR project without facing java.lang.ClassNotFoundException? Classpath vs Build Path vs /WEB-INF/lib
• How do I import the javax.servlet API in my Eclipse project?

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