FileUpload Series: (3) file upload and download examples

The example consists of 1 servlets and 3 JSPs.

1, Fileservlet

package com.rk.web.servlet;import java.io.file;import java.io.fileinputstream;import  java.io.ioexception;import java.io.inputstream;import java.io.outputstream;import  Java.net.urlencoder;import java.util.hashmap;import java.util.list;import java.util.map;import  java.util.UUID;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.fileitemfactory;import  org.apache.commons.fileupload.disk.DiskFileItemFactory;import  org.apache.commons.fileupload.servlet.servletfileupload;/** *  processing file upload and download  * */public  Class fileservlet extends httpservlet {public void doget (HttpServletRequest  request, httpservletresponse response) Throws servletexception, ioexception {//  gets the request parameter:  distinguishes between different operation types String method = request.getparameter (" Method ");if  (" Upload ". Equals (method))  {//  upload upload (request,response);} else if  ("Downlist". Equals (method))  {//  Enter download list downlist (request,response);} else if  ("Down". Equals (method))  {//  download Down (request,response);}} /** * 1.  Upload  */private void upload (httpservletrequest request,  Httpservletresponse response) throws servletexception, ioexception {try {// 1.   Create factory Object Fileitemfactory factory = new diskfileitemfactory ();// 2.  File Upload core tool class Servletfileupload upload = new servletfileupload (Factory);//  Set size limit parameter Upload.setfilesizemax (10*1024*1024);//  single File size limit Upload.setsizemax (50*1024*1024);//  Total file size limit upload.setheaderencoding ("UTF-8");//  to Chinese file encoding processing//  judgment if  (Request )) &NBSP;{//&NBsp;3.  converts the request data to the list collection list<fileitem> list = upload.parserequest (request);//  traversal for   (Fileitem item : list) {//  judgment: Plain Text data if  (Item.isformfield ()) {//  get name string  name = item.getfieldname ();//  Gets the value string value = item.getstring (); System.out.println (value);}  //  file Form Item else {/********  file upload  ***********/// a.  get file name String name  = item.getname ();// ----deal with the name of the upload filename----// a1.  first to get a unique tag string id =  Uuid.randomuuid (). toString ();// a2.  stitching file name name = id +  "#"  + name;//  b.  Get upload directory String basepath = getservletcontext (). Getrealpath ("/upload");// c.   Create a File object to upload File file = new file (basepath,name);// d.  upload item.write (file); Item.delete ();  //  Delete the temporary file generated when the component runs}}}} catch  (exception e)  { E.printstacktrace ();}} /** * 2.  into the download list  */private void downlist (httpservletrequest request,  Httpservletresponse response) throws servletexception, ioexception {//  Realization idea: Get the file name of all files in upload directory first, then save; jump to down.jsp list//1.  Initialize map collection map< file name with unique tag,  short file name >  ; Map<string,string> filenames = new hashmap<string,string> ();//2.  get the upload directory, And all of its files under the file name String bathpath = getservletcontext (). Getrealpath ("/upload");//  directory file  File = new file (Bathpath);//  directory, all Filenames string list[] = file.list ();//  Traverse, Package if  (list != null && list.length > 0) {for  (int i=0 ;  i<list.length; i++) {//  full name string filename = list[i];//  short name string  Shortname = filename.substring (Filename.lastindexof ("#") +1);//  Package Filenames.put (fileName,  shortname);}}  3.  save to request domain reqUest.setattribute ("FileNames",  filenames);// 4.  forwarding Request.getrequestdispatcher ("/downlist.jsp") . Forward (request, response);} /** *  3.  processing Download  */private void down (httpservletrequest request,  Httpservletresponse response) throws servletexception, ioexception {//  Get the file name that the user downloaded ( Append data after URL address, get) string filename = request.getparameter ("FileName"); filename = new  string (Filename.getbytes ("iso8859-1"), "UTF-8");//  get the Upload directory path First string basepath =  Getservletcontext (). Getrealpath ("/upload");//  get a file stream inputstream in = new  FileInputStream (New file (basepath,filename));//  If the file name is Chinese, URL encoding is required filename =  Urlencoder.encode (filename,  "UTF-8");//  set the download response header Response.setheader ("Content-disposition",  " Attachment;filename= " + filename);//  get response byte stream outputstream out =  Response.getoutputstream (); byte[] b = new byte[1024];int len = -1;while  ((Len = in.read (b))  != -1) {out.write (B, 0, len);}   Close Out.close (); In.close ();} Public void dopost (Httpservletrequest request, httpservletresponse response) throws  servletexception, ioexception {this.doget (Request, response);}}

2, index.jsp

<%@ page language= "java" import= "java.util.*" pageencoding= "UTF-8"%><! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >


  
 
<%@ page language= "java"  import= "java.util.*"  pageencoding= "UTF-8"%><! doctype html public  "-//w3c//dtd html 4.01 transitional//en" >


4, downlist.jsp
<%@ page language= "java"  import= "java.util.*"  pageencoding= "UTF-8"%><% @taglib  uri= "Http://java.sun.com/jsp/jstl/core"  prefix= "C"  %><! doctype html public  "-//w3c//dtd html 4.01 transitional//en" >








FileUpload Series: (3) file upload and download examples