1.使用超鏈接下載
缺點：當下載瀏覽器能夠識別的格式就會直接打開，比如圖片，txt等文件。
2.使用程序下載（設置兩個頭Content-Type 和Content-Disposition ）
下載時要設置的頭：
(1)設置 Content-Type 有兩種方法，分別是下面
response.addHeader("Content-Type","image/jpeg"); //用於已經知道文件MIME情況下
response.setContentType(this.getServletContext().getMimeType("文件名")); //這種清開靈是在未知文件類型的情況下 比如動態獲取某文件夾下的所有文件的時候
(2) 設置 Content-Disposition,並且將中文文件名要進行URL編碼
response.addHeader("Content-disposition", "attachment;filename="+URLEncoder.encode(fileName,"utf-8"));(3) ie6瀏覽器在URL編碼時特殊字符轉換有問題，推薦不要在超鏈接中將中文直接發給瀏覽器，而是先進行URL編碼，將編碼好的內容發給瀏覽器，從而能防止ie6自己 進行URL編碼時的錯漏，這種情況多出現在將文件路徑作爲參數傳遞。
單個下載例子，直接訪問sevlet
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Download extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType(this.getServletContext().getMimeType("美人.jpg"));//設置mime
response.addHeader("Content-disposition", "attachment;filename="+URLEncoder.encode("美人.jpg","utf-8"));//中文加編碼
FileInputStream fin = new FileInputStream(this.getServletContext().getRealPath("1.jpg"));
int i = 0;
while((i = fin.read())!=-1){
response.getOutputStream().write(i);
}
fin.close();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
jsp文件
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@page import="java.io.File"%>
<%@page import="java.net.URLEncoder"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<%
Queue<File> queue = new LinkedList();
String path = "c://music";
File rootFile = new File(path);
queue.offer(rootFile);
while(queue.size()>0){
File file = queue.poll();
//如果是一個文件夾，遍歷這個文件夾，將子目錄加入到隊列中
File [] fs = file.listFiles();
for(File f : fs){
if(f.isDirectory())queue.offer(f);
else{
%>
<a href="${pageContext.request.contextPath }/servlet/DownLoadList?path=<%=URLEncoder.encode(f.getAbsolutePath(),"utf-8") %>"><%=f.getName() %></a><br>
<%
}
}
}
%>
</body>
</html>
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DownLoadList extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = request.getParameter("path");
path = new String(path.getBytes("iso8859-1"),"utf-8");
String fileName = path.substring(path.lastIndexOf("\\")+1);
response.setContentType(this.getServletContext().getMimeType(fileName));
response.addHeader("Content-disposition", "attachment;filename="+URLEncoder.encode(fileName,"utf-8"));
FileInputStream fin = new FileInputStream(path);
int i = 0;
while((i = fin.read())!=-1){
response.getOutputStream().write(i);
}
fin.close();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}