关于一个支持多线程下载的Servlet

王朝java/jsp·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

Servelet:

package com.syit.scmis.common;

import java.io.IOException;

import javax.servlet.Servlet;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

* @version 1.0

* @author

*/

public class GetFile

extends HttpServlet

implements Servlet {

/**

* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

*/

public void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

doPost(req,resp);

}

/**

* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

*/

public void doPost(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

req.setCharacterEncoding("GBK");

String spath=req.getParameter("path");

if (spath.equals("")){

java.io.PrintWriter out=resp.getWriter();

out.println("Current directory is invalidate!");

}

else{

if (spath.indexOf("/download")==0){

req.setAttribute("parent",spath.substring(1));

spath=getServletContext().getRealPath(spath);

DownloadFile f=new DownloadFile();

if (f.getFileEx(spath,req,resp)==1){

req.getRequestDispatcher("/download.jsp").forward(req,resp);

}

}else{

java.io.PrintWriter out=resp.getWriter();

out.println("Current directory is invalidate!");

}

}

}

}

主要的工作Java类:

/*

* 创建日期 2004-10-13

*

*/

package com.syit.scmis.common;

import java.io.*;

import java.util.*;

import javax.servlet.http.*;

/**

*

* @author Fuqiming

* @version 1.0

*

*/

public class DownloadFile {

public int getFileEx(String strpath,HttpServletRequest req,HttpServletResponse resp) throws IOException{

File f=new File(strpath);

if (f.isDirectory()){

req.setAttribute("list",getFile(strpath));

return 1;

}

else if (f.isFile()){

downFile(strpath,req,resp);

return 0;

}else {

throw new IOException("path is invalidate");

}

}

public ArrayList getFile(String strpath){

ArrayList array=new ArrayList();

File f=new File(strpath);

File[] fs=f.listFiles();

for (int i=0;i<fs.length;i++){

array.add(fs[i]);

}

return array;

}

public void downFile(String s,HttpServletRequest req,HttpServletResponse resp) throws IOException{

if (s==null){

throw new IOException("File name is must nt null");

}

File file =new File(s);

if (!file.isFile()){

throw new IOException("File is not exist");

}

System.out.println(req.getRemoteAddr()+"请求下载:"+s);

long l=file.length();

long p=0;

resp.reset();

resp.setHeader("Accept-Ranges", "bytes");

if (req.getHeader("Range") != null)

{

resp.setStatus(javax.servlet.http.HttpServletResponse.SC_PARTIAL_CONTENT);

String sclient=req.getHeader("Range");

sclient=sclient.substring("bytes=".length());

if (sclient.charAt(sclient.length()-1)=='-') sclient=sclient.substring(0,sclient.length()-1);

p = Long.parseLong(sclient);

}

resp.setHeader("Content-Length", new Long(l - p).toString());

if (p != 0)

{

resp.setHeader("Content-Range","bytes " + new Long(p).toString() + "-" + new Long(l -1).toString() + "/" + new Long(l).toString());

}

resp.setContentType("application/octet-stream");

resp.setHeader("Content-Disposition",

"attachment;filename="+new String(file.getName().getBytes(),"iso-8859-1"));

long k =0;

int ibuffer=65536;

byte[] bytes=new byte[ibuffer];

FileInputStream fileinputstream = new FileInputStream(file);

try{

if (p!=0) fileinputstream.skip(p);

while (k<l){

int j=fileinputstream.read(bytes,0,ibuffer);

resp.getOutputStream().write(bytes,0,j);

resp.getOutputStream().flush();

k +=j;

}

System.out.println(req.getRemoteAddr()+"请求下载:"+s+"下载完毕");

}

catch(Exception e){

System.err.println("传输"+s+"失败,位置:"+k);

System.err.println(e.getMessage());

}

finally{

fileinputstream.close();

}

}

}

 
 
 
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