文件上传

使用apache的一个开源项目之一：commons-fileupload
很简单的一个使用，其实就是他里面文档中的例子。
本人只是写了个Servlet更具体化它而已。

Servlet:

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

import javax.servlet.RequestDispatcher;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * 
 * @author huanglq
 * 
 */
public class Upload extends HttpServlet {

	private static final long serialVersionUID = 1L;
	//private String uploadPath = "/usr/upload/"; // 上传文件的目录
	private String tempPath = "/usr/upload/tmp/"; // 临时文件目录(上传文件的目的地)
	public static final long MAX_SIZE = 1024*100;

	public Upload() {
		super();
	}

	public void destroy() {
	}

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

		doPost(request, response);
	}

	@SuppressWarnings(value={"unchecked"})
	public void doPost(HttpServletRequest request, HttpServletResponse response)
		throws ServletException, IOException {

		try {
			/*
			//这是以前的方法，现在已经过时了
			DiskFileUpload fu = new DiskFileUpload();
			// 设置最大文件尺寸，这里是4MB
			fu.setSizeMax(4194304);
			// 设置缓冲区大小，这里是4kb
			fu.setSizeThreshold(4096);
			// 设置临时目录：
			fu.setRepositoryPath(tempPath);

			// 得到所有的文件：
			List fileItems = fu.parseRequest(request);
			Iterator i = fileItems.iterator();
			// 依次处理每一个文件：
			while (i.hasNext()) {
				FileItem fi = (FileItem) i.next();
				// 获得文件名，这个文件名包括路径：
				String fileName = fi.getName();
				// 在这里可以记录用户和文件信息
				// ...
				// 写入文件，暂定文件名为a.txt，可以从fileName中提取文件名：
				fi.write(new File(uploadPath + "a.txt"));
			}*/

			/*
			 * 方法1：
			 * 可以上传多个文件不能指定文件大小
			 */
			// Check that we have a file upload request
			boolean isMultipart = ServletFileUpload.isMultipartContent(request);
			System.out.println("isMultipart :"+isMultipart);
			/*
			// Create a factory for disk-based file items
			FileItemFactory factory = new DiskFileItemFactory();
		
			// Create a new file upload handler
			ServletFileUpload upload = new ServletFileUpload(factory);

			// Parse the request
			List  FileItem  items = upload.parseRequest(request);*/

			/*
			 * 方法2:能指定文件大小,超过文件的大小则抛异常
			 */
			// 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(new File(tempPath));//设置

			// Create a new file upload handler
			ServletFileUpload upload = new ServletFileUpload(factory);

			// Set overall request size constraint
			//upload.setSizeMax(1024*1024*4);// 设置最大文件尺寸，这里是4MB
			upload.setSizeMax(MAX_SIZE);// 设置最大文件尺寸，这里是100K,如果上传的文件大于100K程序就出异常
			
			// Parse the request
			List<FileItem> /* FileItem */ items = upload.parseRequest(request);
			
			// Process the uploaded items
			Iterator<FileItem> iter = items.iterator();
			while (iter.hasNext()) {
			    FileItem item = (FileItem) iter.next();
			 // Process a regular form field
			    if (item.isFormField()) {
			        String name = item.getFieldName();
			        String value = item.getString();
			        System.out.println("----------------------");
			        System.out.println("name : "+name);//name : Submit 提交
			        System.out.println("value : "+value);//value : upload 提交的action
			        System.out.println("----------------------");
			    }
			 // Process a file upload
			    boolean flag=!item.isFormField();
			    if (flag) {
			        String fieldName = item.getFieldName();
			        String fileName = item.getName();
			        String contentType = item.getContentType();
			        boolean isInMemory = item.isInMemory();
			        long sizeInBytes = item.getSize();
			        //取文件名
			        fileName=fileName.substring(fileName.lastIndexOf("\\")+1,fileName.length());
			        System.out.println("fieldName : "+fieldName);
			        System.out.println("fileName :"+fileName);
			        System.out.println("contentType : "+contentType);
			        System.out.println("isInMemory : "+isInMemory);
			        System.out.println("sizeInBytes : "+sizeInBytes);
			        System.out.println("***********");
			        
			     // Process a file upload
			        if (flag) {
			        	if(!fileName.equals("")&&!(fileName==null)){//如果fileName为null，即没有上传文件
			        		File uploadedFile = new File("/usr/upload/tmp/"+fileName);
				            item.write(uploadedFile);
			        	}
			        } else {
			            InputStream uploadedStream = item.getInputStream();
			            //File uploadedFile = new File("/usr/upload/test.txt");
			            //uploadedStream
			            uploadedStream.close();
			        }
			    }
			    /*if (item.isFormField()) {
			        processFormField(item);
			    } else {
			        processUploadedFile(item);
			    }*/
			}
			System.out.println("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
			request.setAttribute("uploadSuccess", items);
			RequestDispatcher rd=request.getRequestDispatcher("index.jsp");
			rd.forward(request, response);
			
			
		} catch (Exception e) {
			// 可以跳转出错页面
			System.out.println("ERROR");
			e.printStackTrace();
			
			request.setAttribute("uploadFail", "你上传的文件大于100k!");
			RequestDispatcher rd=request.getRequestDispatcher("index.jsp");
			rd.forward(request, response);
		}
	}

	public void init() throws ServletException {
		// Put your code here
	}

}

Jsp页面：

<%@ page language="java" pageEncoding="gbk"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    
    <title>fileUpload</title>
	<%if(!((request.getAttribute("uploadSuccess"))==null) && !request.getAttribute("uploadSuccess").equals("")){
		%>
		<script type="text/javascript">
		alert("文件上传成功！");
		</script>
		<% 		
	}
	 %>
	 <%if(!((request.getAttribute("uploadFail"))==null) && !request.getAttribute("uploadFail").equals("")){
		%>
		<script type="text/javascript">
		alert("你上传的文件大于100k!");
		</script>
		<% 		
	}
	 %>
  </head>
									
  <body>
	<form action="fileupload" method="post" enctype="multipart/form-data" name="form1">
		<input type="file" name="file">	
		<input type="file" name="file">
		<input type="submit" name="Submit" value="upload">
	</form>
  </body>
</html>

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <servlet>
    <servlet-name>Upload</servlet-name>
    <servlet-class>com.huanglq.util.Upload</servlet-class>
  </servlet>
<servlet>
    <servlet-name>Download</servlet-name>
    <servlet-class>com.huanglq.util.Download</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>Upload</servlet-name>
    <url-pattern>/fileupload</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
  <servlet-mapping>
    <servlet-name>Download</servlet-name>
    <url-pattern>/download</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>