JspServlet实现文件上传与下载.doc

1. Jsp/Servlet:实现文件上传与下载 标签： uploadfilerandomservletdownloadjsp 2012-05-14 11:18 315人阅读 评论(0) 收藏 举报 This doc shows how to upload and download files with Jsp& Servlet technology.author: ZJ07-3-7Blog:url/url1客户端上传文件客户端通过一个Jsp 页面，上传文件到服务器，该Jsp页面必须含有File类表单，并且表单必须设置enctype=multipart/form-data。提交表单 时通过内置对象request，request.getInputStream();方法获得一个输入流。在上传文件时，会有附加信息，如下所示：-7d71042a40328Content-Disposition: form-data; name=fileforload; filename=C:Documents and SettingsZJ桌面book.txtContent-Type: text/plain/此处为文件内容-7d71042a40328Content-Disposition: form-data; name=submitcommit-7d71042a40328-附加信息大小为297字节（不确定这个值，测试得到），可通过request.getContentLength()297来判断是否上传了文件还是提交空字符串。2测试fileupload.jsp负责提交文件，accept.jsp负责实现上传功能。fileupload.jspThis page for FileUploadChoose the file for uploading:accept.jspThis page for response 297) InputStream in = request.getInputStream();File f =newFile(d:/temp,test.txt);FileOutputStream o =newFileOutputStream(f);byteb =newbyte1024;intn;while(n = in.read(b) != -1) o.write(b, 0, n);o.close();in.close();out.print(File upload success!);elseout.print(No file!);catch(IOException e) out.print(upload error.);e.printStackTrace();%服务器端得到的上传文件I like.txt，取名为test.txt-7d75b1540328Content-Disposition: form-data; name=fileforload; filename=C:Documents and SettingsZJ桌面I like.txtContent-Type: text/plain我喜欢驾驭着代码在风驰电掣中创造完美;我喜欢操纵着代码在随心所欲中体验生活;我喜欢用心情代码编制我小小的与众不同;每一段新的代码在我手中延生对我来说就象观看刹那花开的感动;我不需要焦点.因为我就是焦点!-7d75b1540328Content-Disposition: form-data; name=submitcommit-7d75b1540328-3去除附加信息按照HTTP协议，文件表单提交的信息中，前4行和后5行是表单本身的信息，中间部分才是上传的文件的内容。下例对上传的文件进行处理，获取文件名，并去除附加信息。4测试fileupload.jsp不变，accept.jsp修改如下：The real file297)/write the upload content to the temp file.InputStream in=request.getInputStream();byteb=newbyte1024;intn;while(n=in.read(b)!=-1)o.write(b,0,n);o.close();in.close();/read the temp file.RandomAccessFile random=newRandomAccessFile(temp,r);/read Line2 to find the name of the upload second=1;String secondLine=null;while(second=2)secondLine=random.readLine();second+;/get the last location of the dir position=secondLine.lastIndexOf();/get the name of the upload file.String fileName=secondLine.substring(position+1,secondLine.length()-1);/relocate to the head of file.random.seek(0);/get the location of the char.Enter in Line4.longforthEndPosition=0;intforth=1;while(n=random.readByte()!=-1&(forth=0)&(j=6)mark-;random.seek(mark);n=random.readByte();if(n=n)endPosition=random.getFilePointer();j+;/locate to the begin of content.Count for 4 liness end position.random.seek(forthEndPosition);longstartPoint=random.getFilePointer();/read the real content and write it to the realFile.while(startPoint（注：如果文件名是中文，会出现乱码。）5文件下载Jsp内置对象response调用方法getOutputStream（）可以获取一个指向客户的输出流，服务器将文件写入这个流，然后可下载此文件。6测试download.jsp显示下载选项，LoadFile.java（Servlet）负责下载文件。download.jspdownload pageDownload:test.zipLoadFile.javapackagecom.zj.sample;importjava.io.File;importjava.io.FileInputStream;importjava.io.IOException;importjava.io.OutputStream;importjavax.servlet.ServletException;importjavax.servlet.http.HttpServlet;importjavax.servlet.http.HttpServletRequest;importjavax.servlet.http.HttpServletResponse;publicclassLoadFileextendsHttpServlet publicvoiddoGet(HttpServletRequest request, HttpServletResponse response)throwsIOException, ServletException OutputStream o = response.getOutputStream();byteb =newbyte1024;/ the file to download.File fileLoad =newFile(d:/temp,test.rar);/ the dialogbox of download file.response.setHeader(Content-disposition,attachment;filename=+test.rar);/ set the MIME type.response.setContentType(application/x-tar);/ get the file length.longfileLength = fileLoad.length();String length = String.valueOf(fileLength);response.setHeader(Content_Length, length);/ download the file.FileInputStream in =newFileInputStream(fileLoad);intn = 0;while(n = in.read(b) != -1) o.write(b, 0, n);publicvoiddoPost(HttpServletRequest request, HttpServletResponse response)