Servlet实现文件下载
1.JSP页：
<%--
Document : DownloadFile
Created on : 2009-10-11, 21:24:22
Author : lucifer
--%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<form method="post" action="DownLoadFileServlet">
密码：<input type="text" name="password"><br>
<input type="submit" value="submit">
</form>
</body>
</html>
2.Servlet(DownLoadFileServlet):
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
/**
*
* @author lucifer
*/
public class DownLoadFileServlet extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String password = request.getParameter("password");
String filepath = "C:\\Users\\lucifer\\Desktop\\aa.pdf";
if((!checkPassword(password))||password == null){
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=UTF-8");
out.println("<head><title>错误信息</title></head>");
out.println("<h1 align = 'center'>您输入的密码不正确!</h1><hr>");
}
else{
long totalsize = 0;
File f = new File(filepath);
long filelength = f.length();
byte[] b = new byte[1024];
DataInputStream dis = new DataInputStream(new FileInputStream(f));
response.setHeader("Content-dispostion", "attachment;filename=" + filepath);
response.setContentType("application/pdf");
String filesize = Long.toString(filelength);
response.setHeader("Content-Length", filesize);
ServletOutputStream servletOut = response.getOutputStream();
while(totalsize < filelength){
totalsize += 1024;
if(totalsize > filelength){
byte[] leftpart = new byte[1024 - (int)(totalsize - filelength)];
dis.readFully(leftpart);
servletOut.write(leftpart);
}
else{
dis.readFully(b);
servletOut.write(b);
}
}
servletOut.close();
}
}
private boolean checkPassword(String s){
String[] passwords = {"lucifer","lxh"};
boolean flag = false;
for(int i = 0;i < passwords.length;i++){
if(s.equals(passwords[i])){
flag = true;
break;
}
}
return flag;
}
public void init(ServletConfig cfg)
throws ServletException{
super.init(cfg);
}
public void destroy(){
super.destroy();
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
public String getServletInfo() {
return "Short description";
}
}
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