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