servlet的提交和动态改变有点依赖xml
我们点击控件的时候改变了里面的变量，改变了xml，servlet发现变量变了，就会刷新页面
如果xml文档没有更新，浏览器采用缓存而不则行
<form action='"+requestURI+"'method='get'> <input type='text' name='param' value='param string'> <input type='submit' value='用get方式查询"+requestURI+"'></form>
action后面接要发到文档的url，（这个代码是发到自己那里，然后自己的文档更新了，页面也动态更新）
method是我们人为控制用什么方法(get/post
后面有些变量,比如 param...我们后面可以用String param=request.getParameter("param");来获得他
package servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class FirstServlet extends HttpServlet { /** * Constructor of the object. */ public FirstServlet() { super(); } /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * The doGet method of the servlet. <br> * * This method is called when a form has its tag value method equals to get. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.execute(request,response); } /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to post. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.execute(request,response); } /** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */ public void execute(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException { this.log("则行doget方法"); response.setCharacterEncoding("UTF-8"); request.setCharacterEncoding("UTF-8"); String requestURI=request.getRequestURI(); String method=request.getMethod(); String param=request.getParameter("param"); response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">"); out.println("<HTML>"); out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>"); out.println(" <BODY>"); out.println(method+"方式访问该页面。取到的para参数是"+param+"<br/>"); out.println("<form action='"+requestURI+"'method='get'><input type='text' name='param' value='param string'><input type='submit' value='用get方式查询"+requestURI+"'></form>"); out.println("<form action='"+requestURI+"'method='post'><input type='text' name='param' value='param string'><input type='submit' value='用post方式查询"+requestURI+"'></form>"); out.println("<script>document.write('本页面最后更新时间'+document.lastModified);</script>"); out.println(" </BODY>"); out.println("</HTML>"); out.flush(); out.close(); } public void init() throws ServletException { // Put your code here } }