前端代码
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>使用a标签直接指向服务器上的资源</h1>
<a href="/WEB14/download/a.flv" target="_blank" rel="external nofollow" >a.flv</a><br>
<a href="/WEB14/download/a.jpg" target="_blank" rel="external nofollow" >a.jpg</a><br>
<a href="/WEB14/download/a.mp3" target="_blank" rel="external nofollow" >a.mp3</a><br>
<a href="/WEB14/download/a.mp4" target="_blank" rel="external nofollow" >a.mp4</a><br>
<a href="/WEB14/download/a.txt" target="_blank" rel="external nofollow" >a.txt</a><br>
<a href="/WEB14/download/a.zip" target="_blank" rel="external nofollow" >a.zip</a><br>
<h1>使用服务器端编码的方式实现文件下载</h1>
<a href="/WEB14/downloadServlet?filename=a.flv" target="_blank" rel="external nofollow" >a.flv</a><br>
<a href="/WEB14/downloadServlet?filename=a.jpg" target="_blank" rel="external nofollow" >a.jpg</a><br>
<a href="/WEB14/downloadServlet?filename=a.mp3" target="_blank" rel="external nofollow" >a.mp3</a><br>
<a href="/WEB14/downloadServlet?filename=a.mp4" target="_blank" rel="external nofollow" >a.mp4</a><br>
<a href="/WEB14/downloadServlet?filename=a.txt" target="_blank" rel="external nofollow" >a.txt</a><br>
<a href="/WEB14/downloadServlet?filename=a.zip" target="_blank" rel="external nofollow" >a.zip</a><br>
<a href="/WEB14/downLoadServlet2?filename=美女.jpg" target="_blank" rel="external nofollow" >美女.jpg</a><br>
</body>
</html>
后端servlet代码（当文件名出现中文是需要进行处理）
1.将获取的中文乱码名字转换指点编码
2.设置对应的浏览器编码，代码如下：
package com.itheima.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
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);
//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();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
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