java上传组件FileUpload

时间：2023-03-09 16:34:22
java上传组件FileUpload 
如果表单中有文件要上传，也就是有<input type="file" name="name"/>

就需要在form标签中添加enctype="multipart/form-data"属性 如果添加此属性，在操作

页面servlet中，用request.getParameter("name")获取普通表单数据就会

出错java.lang.NullPointerException

可以使用FileUpload组件操作上传文件

1，导入jar包；commons-fileupload-1.2.2.jar   commons-io-1.4.jar

上传jsp页面fileupload.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>上传表单</title>

</head>

<body>

	<form action="${pageContext.request.contextPath }/servletupload1" method="post" enctype="multipart/form-data">

	<p>用户名：<input type="text" name="username"></p>

	<input type="file" name="file1"/><br/>

	<input type="file" name="file2"/><br/>

	<input type="submit" value="上传"/>

	</form>

</body>

</html>

servlet页面进行操作

package com.henau.fileupload;

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.FileUploadException;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class servletupload1 extends HttpServlet {

	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		response.setCharacterEncoding("UTF-8");

		DiskFileItemFactory factory=new DiskFileItemFactory();//磁盘工厂

		ServletFileUpload upload=new ServletFileUpload(factory);//创建处理工具

		if(!upload.isMultipartContent(request)){//判断是否有multipart/form-data

			return;

		}

		upload.setHeaderEncoding("UTF-8");//解决中文文件名乱码问题

		upload.setFileSizeMax(10*1024*1024);//设置最大上传文件10M

		try {

			List<FileItem> items=upload.parseRequest(request);//获取表单列表

			Iterator<FileItem> it=items.iterator();//获取列表迭代器

			while(it.hasNext()){

				FileItem item=it.next();

				String fieldname=item.getFieldName();

				if(!item.isFormField()){//isFormField()是否是普通文本

					response.getWriter().write(fieldname+":文件大小:"+item.getSize()+"<br/>");

					response.getWriter().write(fieldname+":文件名称:"+item.getName()+"<br/>");

					response.getWriter().write(fieldname+":文件类型:"+item.getContentType()+"<br/>");

				}else{

					response.getWriter().write(fieldname+":普通文本数据:"+item.getString("UTF-8")+"<br/>");

				}

			}

		} catch (FileUploadException e) {

			e.printStackTrace();

		}

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		doGet(request, response);

	}

}

页面显示效果

username:普通文本数据:用户名

file1:文件大小:14

file1:文件名称:IO流.txt

file1:文件类型:text/plain

file2:文件大小:2621

file2:文件名称:javaSE需求.txt

file2:文件类型:text/plain

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