文件上传在web应用中是非常常见的，现在我就介绍下基于servlet的文件上传，基于Struts2的文件上传可以看：
页面端代码：
<%@ page language="java" import="java.util.*" pageEncoding="GBK"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>注册</title> </head> <body> <form name="form1" onsubmit="return on_submit()" action="RegisterServlet" method="post" enctype="multipart/form-data"> <input type="text" name="uname1" id="password" /> <input type="text" name="uname2" id="uname2"/> <input type="password" name="password1" id="password" /> <input type="password" name="password2" id="password"/> <input type="radio" value="男" checked="checked" name="sex"/>男 <input type="radio" value="女" name="sex"/>女 <input type="text" name="email" value="" class="box" id="login" /> <br/><br/> <input type="file" name="file1" id="file"/> <input type="submit" name="submit" value="完成注册" /> </form> </body> </html>
这里要注意的一点就是存在文件上传的form表单必须封装为enctype="multipart/form-data"；这里我们直接与后台进行交互，不进行Ajax交互，需要使用ajax可以看：
http://www.cnblogs.com/shenliang123/category/372520.html
下面我们继续来看servlet的代码实现：
package com.xidian.bbs.servlet; import java.io.IOException; import java.io.PrintWriter; import java.net.InetAddress; import java.sql.Connection; import java.sql.ResultSet; import java.sql.Statement; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.jsp.JspFactory; import javax.servlet.jsp.PageContext; import com.jspsmart.upload.*; import com.xidian.bbs.bean.Bean; import com.xidian.bbs.bean.RegisterBean; import com.xidian.bbs.util.DBAccess; import com.xidian.bbs.util.IpTimeStamp; @SuppressWarnings("serial") public class RegisterServlet extends HttpServlet{ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); response.setCharacterEncoding("GBK"); request.setCharacterEncoding("GBK"); SmartUpload smart=new SmartUpload(); try{ //PageContext是jsp的内置对象，在servlet不能直接使用，需要做一些处理 JspFactory _jspxFactory = null; PageContext pageContext = null; _jspxFactory = JspFactory.getDefaultFactory(); pageContext = _jspxFactory.getPageContext(this,request,response,"",true,8192,true); smart.initialize(pageContext);//初始化上传操作 smart.upload(); IpTimeStamp its=new IpTimeStamp(InetAddress.getLocalHost().getHostAddress());//request.getRemoteAddr()获得用户的ip地址 //System.out.println("获取的ip为"+InetAddress.getLocalHost().getHostAddress()); //如果要实现文件的批量上传，则只需用for循环，将getFile(0)中的0改为i即可 String ext=smart.getFiles().getFile(0).getFileExt();//此为得到文件的扩展名,getFile(0)为得到唯一的一个上传文件 String fileName=its.getIpTimeRand()+"."+ext; //System.out.println("获取 的文件名为"+fileName); //this.getServletContext().getRealPath("/")为得到tomcat的跟目录，放于upload文件夹中，java.io.File.separator是一种安全操作 //String realPath=""; //this.getServletContext().getRealPath("/")+ smart.getFiles().getFile(0).saveAs("/headupload"+java.io.File.separator+fileName); String realPath="headupload/"+fileName+""; // //由于前面的form表单已经进行了封装，这里就不能简单的用request.getparameter()来获取表单参数 String uname1 = smart.getRequest().getParameter("uname1");//昵称 String upass1 = smart.getRequest().getParameter("password1"); String sex = smart.getRequest().getParameter("sex"); String uname2 = smart.getRequest().getParameter("uname2");//用户名 String email = smart.getRequest().getParameter("email"); PrintWriter out = response.getWriter(); //以下是持久层操作，省略。。。。。。。。。。 } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request,response); } }
上面使用到的ip+时间戳的类IpTimeStamp对文件进行重命名：http://www.cnblogs.com/shenliang123/archive/2012/04/19/2456645.html