Servlet 06响应头信息

最新推荐文章于 2022-08-02 14:40:37 发布

转载最新推荐文章于 2022-08-02 14:40:37 发布 · 368 阅读

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本文介绍了如何使用Java Servlet实现动态响应Excel文件、JPEG图片的方法，并展示了如何设置HTTP响应头实现网页定时刷新。

响应头信息：

协议，状态码，header......

setHeader设置响应头信息

设置内容类型，如word，excel，txt等等

1.构建excel电子表格

代码如下：

[html] view plain copy

print ?

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("application/vnd.ms-excel");
PrintWriter out = response.getWriter();
out.println("\tQ1\tQ2\tQ3\tQ4\tTotal");
out.println("Apples\t78\t87\t92\t29\t=SUM(B2:E2)");
out.println("Oranges\t77\t86\t93\t30\t=SUM(B3:E3)");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}

public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
			response.setContentType("application/vnd.ms-excel");
	    PrintWriter out = response.getWriter();
		  out.println("\tQ1\tQ2\tQ3\tQ4\tTotal");
		  out.println("Apples\t78\t87\t92\t29\t=SUM(B2:E2)");
		  out.println("Oranges\t77\t86\t93\t30\t=SUM(B3:E3)");
		
	}

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

2.动态生成jpeg图片

代码内容如下：

[html] view plain copy

print ?

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//响应动态图片
response.setContentType("image/jpeg"); //设置响应头响应内容类型为图片
/*this.getClass().getClassLoader().getResourceAsStream()路径采用相对路径直接可以从工程的path路径去找。
* 这里name是资源的类路径，它是相对与“/”根路径下的位置。getResource得到的是一个URL对象来定位资源，
* 而getResourceAsStream取得该资源输入流的引用保证程序可以从正确的位置抽取数据
* */
InputStream in = this.getClass().getClassLoader().getResourceAsStream("girl.jpeg"); //获得输入流图片
int len = in.available(); //统计字节长度
byte[] buffer = new byte[len];
in.read(buffer); //读取字符节
OutputStream out = response.getOutputStream(); //输出流
out.write(buffer); //向输出流中写入字节信息
out.flush();
out.close();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}

          public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		  //响应动态图片
		  response.setContentType("image/jpeg");                                               //设置响应头响应内容类型为图片

                   /*this.getClass().getClassLoader().getResourceAsStream()路径采用相对路径直接可以从工程的path路径去找。
		   * 这里name是资源的类路径，它是相对与“/”根路径下的位置。getResource得到的是一个URL对象来定位资源，
		   * 而getResourceAsStream取得该资源输入流的引用保证程序可以从正确的位置抽取数据
		   * */
		  InputStream in = this.getClass().getClassLoader().getResourceAsStream("girl.jpeg");  //获得输入流图片
		  int len = in.available();                                                            //统计字节长度
		  byte[] buffer = new byte[len];
		  in.read(buffer);                                                                     //读取字符节
		  OutputStream out = response.getOutputStream();                                       //输出流
		  out.write(buffer);                                                                   //向输出流中写入字节信息
		  out.flush();
		  out.close();
	}

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

3.定时刷新页面

代码内容如下：

[html] view plain copy

print ?

//3.定时刷新页面
response.setHeader("refresh", "1");//每隔1秒刷新一次
response.setContentType("text/html;charset=gbk");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML>");
out.println("<html>");
out.println("<head><title>Refresh Servlet</title></head>");
out.println("<body>");
out.print("当前刷新时间为：");
out.print(new Date().toLocaleString());
out.println("</body>");
out.println("</html>");

                 //3.定时刷新页面
		  response.setHeader("refresh", "1");//每隔1秒刷新一次
		  response.setContentType("text/html;charset=gbk");
		  PrintWriter out = response.getWriter();
		  out.println("<!DOCTYPE HTML>");
		  out.println("<html>");
		  out.println("<head><title>Refresh Servlet</title></head>");
		  out.println("<body>");
		  out.print("当前刷新时间为：");
		  out.print(new Date().toLocaleString());
		  out.println("</body>");
		  out.println("</html>");

比如一个直播NBA视频，当前时间两队的比分的显示。