Http请求和响应应用

 //以下载方式打开资源
     public void test4(HttpServletResponse response) throws IOException {
         response.setHeader("content-disposition", "attachment;filename=1.bmp");
         InputStream in = this.getServletContext().getResourceAsStream("/1.bmp");
         int len = 0;
         byte buffer[] = new byte[1024];
         OutputStream out = response.getOutputStream();
         while((len=in.read(buffer))>0){
             out.write(buffer, 0, len);
         }
     }
     //设置响应头，每隔3秒刷新一次
     public void test3(HttpServletResponse response) throws IOException {
         response.setHeader("refresh", "3");//可以用在股票里
         //response.setHeader("refresh", "3:url='http://www.sina.com'");3秒之后刷新到新浪上面去
         //在论坛上，会说3秒后去哪，就是用到这个技术。
         String data = "aaaaaaaaaaaaa";//服务器从浏览器得到的数据
         response.getOutputStream().write(data.getBytes());
     }
     //通过content-type字段控制浏览器以哪种方式打开数据
     public void test2(HttpServletResponse response) throws IOException {
         response.setHeader("content-type", "image/bmp");
         InputStream in = this.getServletContext().getResourceAsStream("/1.bmp");
         int len = 0;
         byte buffer[] = new byte[1024];
         OutputStream out = response.getOutputStream();
         while((len=in.read(buffer))>0){
             out.write(buffer, 0, len);
         }
     }

     //压缩数据输出
     public void test1(HttpServletResponse response) throws IOException {
         String data="aaaaaaaaa";
         ByteArrayOutputStream bout = new ByteArrayOutputStream();
         GZIPOutputStream gout = new GZIPOutputStream(bout);
         //ByteArrayOutputStream叫底层流，GZIPOutputStream包装流，包装流会有一个缓冲的，调用包装流写数据的时候，
         //如果数据量没有把包装流的缓冲写满，他是不会往底层流里面写的，为了确保一定能够取到数据，添加gout.close();
         gout.write(data.getBytes());
         gout.close();
         byte gzip[] = bout.toByteArray();//得到压缩后的数据
         //给浏览器之后浏览器不知道是压缩数据，一定要通过设置响应头，通知浏览器数据采用的压缩格式,不然会出现错误
         response.setHeader("Content-Encoding", "gzip");
         response.setHeader("Content-Length", gzip.length+"");
         response.getOutputStream().write(gzip);
     }
 //实现断点下载，请求里面包含range头
     public static void test6() throws MalformedURLException, IOException,
             FileNotFoundException {
         //已接受aaaaa  源文件aaaaaaaaaaaaaaaaaaaaa
         URL url = new URL("http://localhost:8080/day05/a.txt");
         HttpURLConnection conn = (HttpURLConnection) url.openConnection();
         conn.setRequestProperty("Range", "bytes=5-");

         InputStream in = conn.getInputStream();

         int len=0;
         byte buffer[] = new byte[1024];
         FileOutputStream out = new FileOutputStream("c:\\a.txt",true);//追加
         while((len=in.read(buffer))>0){
             out.write(buffer, 0, len);
         }
         in.close();
         out.close();
     }