使用代码下载

1 package cn.servlet; 2  3 import java.io.FileInputStream; 4 import java.io.IOException; 5 import java.io.InputStream; 6 import java.io.OutputStream; 7 import java.net.URLEncoder; 8  9 import javax.servlet.ServletException;10 import javax.servlet.http.HttpServlet;11 import javax.servlet.http.HttpServletRequest;12 import javax.servlet.http.HttpServletResponse;13 14 public class DownServlet extends HttpServlet {15     @Override16     public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {17         System.err.println("判断用户的积分信息.....");18         //获取真实的文件19         String path = getServletContext().getRealPath("/files/cos.jar");20         //获取这个文件的io21         InputStream in = 22                 new FileInputStream(path);23         //设置响应的头信息24         //如果希望将下载的文件修改成中文名，则必须要对中文名称进行编码25         String name = "下载的文件.jar";26         name = URLEncoder.encode(name,"UTF-8");27         resp.setHeader("Content-Disposition","attachment;filename="+name);28         resp.setContentType("application/force-download");29         30         byte[] bs = new byte[1024];31         OutputStream out = 32                 resp.getOutputStream();33         int len = 0;34         while((len=in.read(bs))!=-1){35             out.write(bs,0,len);36         }37         in.close();38         out.close();39     }40 }41 42 
43     下载44     
45     Download

自己使用urlconnection实现下载

1 package cn.client; 2  3 import java.io.FileOutputStream; 4 import java.io.InputStream; 5 import java.io.OutputStream; 6 import java.net.HttpURLConnection; 7 import java.net.URL; 8 public class Client { 9     public static void main(String[] args) throws Exception {10         //1:声明url地址11         URL url = new URL("http://localhost:8080/20151116/files/cos.jar");12         HttpURLConnection con = 13                 (HttpURLConnection) url.openConnection();14         con.setRequestMethod("GET");15         con.setDoOutput(true);16         con.setDoInput(true);17         con.setConnectTimeout(3000);18         con.connect();19         20         //获取连接的状态21         int code = con.getResponseCode();22         if(code==200){23             InputStream in = 24                     con.getInputStream();25             byte[] bs = new byte[1024];26             int len = 0;27             OutputStream out = new FileOutputStream("d:/a/a.jar");28             while((len=in.read(bs))!=-1){29                 out.write(bs, 0, len);30             }31             out.close();32             in.close();33         }34         con.disconnect();35     }36 }