request和response的知识

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1response.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);}}