需要两个jar包：
commons-fileupload.jar
Commons IO的jar包（本文使用commons-io-2.4.jar）
利用Servlet来实现文件上传。
package web.servlet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.File; import java.util.Iterator; import java.util.List; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; /** * Servlet implementation class UploadServlet */ @WebServlet("/UploadServlet") public class UploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; private String uploadPath = "D:\temp"; // 上传文件的目录 private String tempPath = "d:\temp\buffer\"; // 临时文件目录 File tempPathFile; public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { try { // Create a factory for disk-based file items DiskFileItemFactory factory = new DiskFileItemFactory(); // Set factory constraints factory.setSizeThreshold(4096); // 设置缓冲区大小，这里是4kb factory.setRepository(tempPathFile);// 设置缓冲区目录 // Create a new file upload handler ServletFileUpload upload = new ServletFileUpload(factory); // Set overall request size constraint upload.setSizeMax(4194304); // 设置最大文件尺寸，这里是4MB List<FileItem> items = upload.parseRequest(request);// 得到所有的文件 Iterator<FileItem> i = items.iterator(); while (i.hasNext()) { FileItem fi = (FileItem) i.next(); String fileName = fi.getName(); if (fileName != null) { File fullFile = new File(fi.getName()); File savedFile = new File(uploadPath, fullFile.getName()); fi.write(savedFile); } } System.out.print("upload succeed"); } catch (Exception e) { // 可以跳转出错页面 e.printStackTrace(); } } public void init() throws ServletException { File uploadFile = new File(uploadPath); if (!uploadFile.exists()) { uploadFile.mkdirs(); } File tempPathFile = new File(tempPath); if (!tempPathFile.exists()) { tempPathFile.mkdirs(); } } }
jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 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=GB18030"> <title>File upload</title> </head> <body> <!-- // action="fileupload"对应web.xml中<servlet-mapping>中<url-pattern>的设置. --> <form name="myform" action="UploadServlet" method="post" enctype="multipart/form-data"> File:<br> <input type="file" name="myfile"><br> <br> <input type="submit" name="submit" value="Commit"> </form> </body> </html>
这样就能简单实现一个文件上传功能了，当然这是最最最基本的，继续研究中。