request和response的知识
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- public class Demo1 extends HttpServlet {
- public void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doPost(request, response);
- }
- //在servlet中用outputstream输出中文的问题
- public void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- test4(response);
- }
- private void test4(HttpServletResponse response)
- throws IOException, UnsupportedEncodingException {
- //如果servle的代码写成这样"response.getOutputStream().write(1);",因为
- //浏览器默认的编码是gb2312,那么它会去寻找编号为1所对应的字符,结果是为"",
- //如果写成字符串"1"的话,那么这个1字符是经过getBytes之后的,所以会直接输出1
- response.getOutputStream().write(1);
- response.getOutputStream().write("1".getBytes());
- }
- private void test3(HttpServletResponse response)
- throws IOException, UnsupportedEncodingException {
- String name="中国3";
- //如果程序把text/html后面的;写成了,的话,那么浏览器会提示下载此servlet文件
- response.setHeader("Content-type", "text/html,charset=UTF-8");
- response.getOutputStream().write(name.getBytes("UTF-8"));
- }
- private void test2(HttpServletResponse response)
- throws IOException, UnsupportedEncodingException {
- String name="中国2";
- //用html技术中的meta标签来模拟http的响应头,来控制浏览器的行为
- response.getOutputStream().write("<meta http-equiv='content-type' content='text/type;charset=UTF-8'>".getBytes());
- response.getOutputStream().write(name.getBytes("UTF-8"));
- }
- private void test1(HttpServletResponse response)
- throws IOException, UnsupportedEncodingException {
- String name="中国1";
- //程序以什么码表输出了,程序就要控制浏览器以什么样的码表打开
- response.setHeader("Content-type", "text/html;charset=UTF-8");
- //response.getOutputStream().write(name.getBytes());
- response.getOutputStream().write(name.getBytes("UTF-8"));
- }
- }
- public class Demo2 extends HttpServlet {
- public void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doPost(request, response);
- }
- //通过response的wirter流输出数据
- public void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- //因为在servlet传递给浏览器的过程中是通过response进行编码后传递的,而老外默认是
- //使用iso8859-1来进行编码传递的,所以我们需要对response的编码进行设置,以控制
- //response以什么码表向浏览器写出数据
- //测试得知,在设置response的编码时最好写在上面
- //第一种方式,控制response的编码和浏览器显示的编码,因为浏览器默认是gb2312的
- //response.setCharacterEncoding("utf-8");
- //下面这句通过response设置浏览器的编码,其实默认同时也把response的编码也给设置了,所以上面的那句话也可以省略掉了
- //response.setContentType("text/html;charset=utf-8");
- //第二种方式,控制response的编码与浏览器的一致,也就是gb2312编码
- response.setCharacterEncoding("gb2312");
- String name="中国";
- PrintWriter out=response.getWriter();
- //第三种方式,不设置response的编码,使用默认的iso8859-1,然后把string转化为8859-1后进行传递
- //out.print(new String(name.getBytes(),"iso8859-1"));
- out.print(name);
- }
- }
- //文件下载
- public class Demo3 extends HttpServlet {
- public void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doPost(request, response);
- }
- public void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- String path=this.getServletContext().getRealPath("/download/小破孩.jpg");
- String filename=path.substring(path.lastIndexOf("/")+1);
- //如果下载文件是中文文件,那么文件名需要经过url编码
- response.setHeader("content-disposition", "attachment;filename="+URLEncoder.encode(filename,"utf-8"));
- InputStream is=new FileInputStream(path);
- OutputStream os=response.getOutputStream();
- int len=0;
- byte[] bs=new byte[1024];
- while((len=is.read(bs))>0){
- os.write(bs, 0, len);
- }
- os.close();
- is.close();
- }
- }
- public class Demo5 extends HttpServlet {
- public void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doPost(request, response);
- }
- public void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- //test1(response);
- //test2(response);
- test3(request,response);
- }
- //实用的跳转技术,最终的信息还是要在浏览器中显示比较好,这样的话容易排版,test2中是输出的是直接页面的源代码
- private void test3(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
- String message="<meta http-equiv='refresh' content='3;url=/testweb/index.jsp'>恭喜你,登录成功了,本浏览器将在3秒后,跳到首页,如果没有跳,<a href=\"/index.jsp\">请点击此处</a>";
- request.setAttribute("message", message);
- this.getServletContext().getRequestDispatcher("/forword.jsp").forward(request, response);
- }
- private void test2(HttpServletResponse response) throws IOException {
- //假设这是一个用于登录的Servlet
- //假设程序运行到此,用户登录成功了
- response.setContentType("text/html;charset=gb2312");
- response.setHeader("refresh", "3;url='/testweb/index.jsp'");
- response.getWriter().write("恭喜你,登录成功了,本浏览器将在3秒后,跳到首页,如果没有跳,<a href=\"/index.jsp\">请点击此处</a>");
- }
- private void test1(HttpServletResponse response) throws IOException {
- response.setHeader("refresh", "3");//每隔三秒刷新一次
- int data=new Random().nextInt(1000);
- response.getWriter().println(data);
- }
- }
- public class Demo5 extends HttpServlet {
- public void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- //使用expries缓存当前内容
- response.setDateHeader("expires", System.currentTimeMillis()+1000*3600);
- String data="bbbbbbbbbbbbbbbbbb";
- System.out.println("访问---");
- response.getWriter().write(data);
- }
- public void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doGet(request, response);
- }
- }
- /**
- * 重定向的特点:
- * 1.浏览器会向服务器发送两次请求,意味着就有两个request/response
- * 2.用重定向技术,地址栏会发生变化
- *
- *用户登录和购物车时,通常会用到重定向技术
- *
- *同时调用getOutPutStream()和getWriter()会抛出异常
- */
- public class Demo6 extends HttpServlet {
- public void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- /*sendRedirect的内部原理
- response.setStatus(302);
- response.setHeader("location", "/testweb/index.jsp");
- */
- response.sendRedirect("/testweb/index.jsp");
- }
- public void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doGet(request, response);
- }
- }
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