【javaweb:servlet】从服务端下载中文名称文件应该注意的问题！！！

package com.content;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import sun.misc.BASE64Encoder;

public class DownLoadServlet2 extends HttpServlet {

protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

//*******文件名称是中文的下载*******

//获得要下载的文件的名称
String filename = request.getParameter("filename");//????.jpg
//解决获得中文参数的乱码----下节课讲
filename = new String(filename.getBytes("ISO8859-1"),"UTF-8");//美女.jpg

//获得请求头中的User-Agent
String agent = request.getHeader("User-Agent");
//根据不同浏览器进行不同的编码
String filenameEncoder = "";
if (agent.contains("MSIE")) {
// IE浏览器
filenameEncoder = URLEncoder.encode(filename, "utf-8");
filenameEncoder = filenameEncoder.replace("+", " ");
} else if (agent.contains("Firefox")) {
// 火狐浏览器
BASE64Encoder base64Encoder = new BASE64Encoder();
filenameEncoder = "=?utf-8?B?"
+ base64Encoder.encode(filename.getBytes("utf-8")) + "?=";
} else {
// 其它浏览器
filenameEncoder = URLEncoder.encode(filename, "utf-8");
}

//要下载的这个文件的类型-----客户端通过文件的MIME类型去区分类型
response.setContentType(this.getServletContext().getMimeType(filename));
//告诉客户端该文件不是直接解析 而是以附件形式打开(下载)----filename="+filename 客户端默认对名字进行解码
response.setHeader("Content-Disposition", "attachment;filename="+filenameEncoder);
//这儿的filenameEncoder是对"美女.jpg"进行针对不同浏览器进行的编码，
//不再是"美女.jpg",因为它不识别(导致下载的文件没名称)

//获取文件的绝对路径
String path = this.getServletContext().getRealPath("download/"+filename);
//获得该文件的输入流
InputStream in = new FileInputStream(path);
//获得输出流---通过response获得的输出流 用于向客户端写内容
ServletOutputStream out = response.getOutputStream();
//文件拷贝的模板代码
int len = 0;
byte[] buffer = new byte[1024];
while((len=in.read(buffer))>0){
out.write(buffer, 0, len);
}

in.close();
//out.close();out.close()可不必写

}

protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}