Servlet上传文件详细解析以及注意事项

1、Servlet上传文件详细解析以及注意事项本文主要介绍了 Servlet上传文件详细解析以及注意事项，分别用两个阶段来进行详细讲解。 准备阶段，下载需要的包：在Servlet中进行文件上传需要用到外部的类库，apache提供了这些类库，主要需要com mon s-fileupload.jar 禾口 com mon s-io.jar下载的步骤如下：进入 网站,在 Projects 下找至U commons 点击进入找至UComponents下的FileUpload,点击进入就可以找到下载页面如下：UocumentationThe following document

2、ation is available:* User Guidfi* Streaming API* Frequently Ased Questions阳Dtx API卩oicct RtHJortGrou can also browse the Subversion repository.* Download the binary and source distribut ons from a mirroi site here 於FileUpload 1.2.1 - 18 January 2008 Download the binary and source distribut ons from

3、a mirror site h赴赴 可以看到这里有开发指南和下载地址，如果要详细学习，慢慢看这里的资源就可以了。com mon s-io.jar 包的下载地址:/fileupload/dependencies.html把两个jar包放到WEB-INF的lib目录下。开发阶段：上传页面：index.jsp1. 2. 6.7. 8. 9. 10.base href=11.12. 文件上传 6.keywordscontent= keyword1,keyword2,keyword317.18.!-19.20.-21. 22.23. 2

4、4.25.文件别名:26.选择文件:27.28.29. 30. 31. 这里注意第 24 行，上传文件时要指定提交方法 method=post, 信息类型为 enctype=multipart/form-data上传功能 servlet:FileUpload1.packagecom.sunflower.servlet;2.3.importjava.io.File;4.importjava.io.IOException;5.importjava.util.Iterator;6.importjava.util.List;9.20.

5、5.46.47.import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import mons.fileupload.FileItem;import

6、 mons.fileupload.FileItemFactory;import mons.fileupload.FileUploadException;import mons.fileupload.disk.DiskFileItemFactory;import mons.fileupload.servlet.ServletFileUpload;public class FileUpload extends HttpServlet protected void doPost(HttpS

7、ervletRequest req, HttpServletRespons e resp)throws ServletException, IOException req.setCharacterEncoding( UTF-8 );fileControl(req, resp);/* 上传文件的处理*/private void fileControl(HttpServletRequest req, HttpServletResp onse resp) throws ServletException / 在解析请求之前先判断请求类型是否为文件上传类型 boolean isMultipart = S

8、ervletFileUpload.isMultipartContent(req);/ 文件上传处理工厂FileItemFactory factory =new DiskFileItemFactory();/ 创建文件上传处理器ServletFileUpload upload = new ServletFileUpload(factory);/ 开始解析请求信息List items = null ;try items = upload.parseRequest(req);catch (FileUploadException e) e.printStackTrace();48./ 对所有请求信息进

9、行判断49.Iterator iter = items.iterator();50.while (iter.hasNext() 51.FileItem item = (FileItem) iter.next();52./ 信息为普通的格式53.if (item.isFormField() 54.String fieldName = item.getFieldName();55.String value = item.getString();56.req.setAttribute(fieldName, value);57.58./ 信息为文件格式59.else 60.String fileNam

10、e = item.getName();61.int index = fileName.lastIndexOf( );62.fileName = fileName.substring(index +163.req.setAttribute( realFileName, fileName);64.65./ 将文件写入66./String path = req.getContextPath();67./String directory = uploadFile;68./String basePath = req.getScheme() + :/ + req.getServerName() + : +

11、 req.getServerPort() + path + / + directory;69.String basePath = req.getRealPath(/uploadFile );70.File file = newFile(basePath, fileName);71.try 72.item.write(file);73.74.catch (Exception e) 75.e.printStackTrace();9.80.try 81.req.getRequestDispatcher(/uploadsuccess.jsp ).forward(req, resp)

12、;82.83.catch (IOException e) 84.e.printStackTrace();85.86.这里要注意第6668行，将文件上传到 Web项目的uploadFile文件夹中，如果用这种方法得到的路径是 http:/localhost:8080/upload/uploadFile,而创建 File 类用的路径是绝对路径，这样就会出问题，所以这里要用的是得到真实路径的方法 HttpServletRequest.getRealPath().以上是最简单的文件上传，如果要加入上传的限制可以在 DiskFileItemFactory 和 ServletFileUpload 中进行限制 :在 34 行后加入：1. / 创建临时文件目录2. File tempFile =new File(req.getRealPath( /temp );3. / 设置缓存大小4. (DiskFileItemFactory) factory).setSizeThreshold(1024 *1024 );5. / 设置临时文件存放地点6. (DiskFileItemFactory) factory).setRepository(tempFile)