文件路径：
download.html1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>Title</title> 6 </head> 7 <body> 8 <a href="/day13_tomcat/downloadServlet?filename=皮卡丘.jpg">图片</a> 9 <a href="/day13_tomcat/downloadServlet?filename=duanwu.mp3">音乐</a>10 <a href="/day13_tomcat/downloadServlet?filename=huli.avi">视频</a>11 </body>12 </html>
DownloadServlet类
1 package cn.itcast.web.servlet; 2 3 import cn.itcast.utils.DownloadUtils; 4 5 import javax.servlet.ServletContext; 6 import javax.servlet.ServletException; 7 import javax.servlet.ServletOutputStream; 8 import javax.servlet.annotation.WebServlet; 9 import javax.servlet.http.HttpServlet;10 import javax.servlet.http.HttpServletRequest;11 import javax.servlet.http.HttpServletResponse;12 import java.io.FileInputStream;13 import java.io.IOException;14 15 @WebServlet(urlPatterns = "/downloadServlet")16 public class DownloadServlet extends HttpServlet {17 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {18 // 1.获取请求参数，文件名称19 String filename = request.getParameter("filename");20 // 2.使用字节输入流加载文件进内存21 // 2.1找到文件服务器路径22 ServletContext context = request.getServletContext();23 String realPath = context.getRealPath("/img/" + filename);24 // 2.2用字节流关联25 FileInputStream fis = new FileInputStream(realPath);26 27 // 3.设置response的响应头28 // 3.1设置响应头类型：content-type29 String mimeType = context.getMimeType(filename);30 response.setHeader("content-type", mimeType);31 32 // 解决中文文件名问题33 // 获取user-agent请求头34 String agent = request.getHeader("user-agent");35 // 使用DownloadUtils工具类方法编码文件名36 filename = DownloadUtils.getFileName(agent, filename);37 38 // 3.2设置响应头打开方式：content-disposition39 response.setHeader("content-disposition", "attachment; filename="+filename);40 41 // 4.将输入流的数据写到输出流中42 ServletOutputStream sos = response.getOutputStream();43 byte[] b = new byte[1024 * 8];44 int len = 0;45 while((len = fis.read(b)) != -1){46 sos.write(b, 0, len);47 }48 }49 50 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {51 this.doPost(request, response);52 }53 }
DownloadUtils工具类
1 package cn.itcast.utils; 2 3 import sun.misc.BASE64Encoder; 4 import java.io.UnsupportedEncodingException; 5 import java.net.URLEncoder; 6 7 8 public class DownloadUtils { 9 10 public static String getFileName(String agent, String filename) throws UnsupportedEncodingException {11 if (agent.contains("MSIE")) {12 // IE浏览器13 filename = URLEncoder.encode(filename, "utf-8");14 filename = filename.replace("+", " ");15 } else if (agent.contains("Firefox")) {16 // 火狐浏览器17 BASE64Encoder base64Encoder = new BASE64Encoder();18 filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";19 } else {20 // 其它浏览器21 filename = URLEncoder.encode(filename, "utf-8");22 }23 return filename;24 }25 }