常用的web服务器有： 1、IIS,出自微软 2、Apache,linux，C语言写的 3、tomcat是Apache项目中的一个，java写的
servlet是服务器上运行的程序其主要功能在于交互式地浏览和修改数据，生成动态Web内容。
先记录下功能代码吧，关于servlet的原理，等之后学习更深入了，再补充一下。
生命周期public class TestLiftCycleServlet extends HttpServlet { /** * 实例化 */ public TestLiftCycleServlet() { System.out.PRintln("constructor"); } /** * 处理请求 多次使用 */ @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("doGet"); } /** * 初始化 只执行一次 */ @Override public void init(ServletConfig config) throws ServletException { System.out.println("init"); } /** * 退出服务时调用 */ @Override public void destroy() { System.out.println("destroy"); }}显示一个点击跳转的功能package com.hq.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/HelloWorld")public class HelloWorld extends HttpServlet { private static final long serialVersionUID = 1L; public HelloWorld() { super(); } @Override protected void service(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException { super.service(arg0, arg1); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.getWriter().write("<a href='http://www.baidu.com'>go</a>"); PrintWriter out = response.getWriter(); out.print(" 这个一个百度跳转 "); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response);//和get使用同一套处理方法 }}获取onSubmit指定参数值package com.hq.servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ThreeParams extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { PrintWriter pw = resp.getWriter(); pw.println("获取到的参数 <br/>"); pw.println(req.getParameter("param1")); pw.println("<br/>"); pw.println(req.getParameter("param2")); pw.println("<br/>"); pw.println(req.getParameter("param3")); pw.println("<br/>"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("post"); doGet(req, resp); }}获取全部提交参数package com.hq.servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ReadAllParamsServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html;charset=gb2312"); PrintWriter pw = resp.getWriter(); pw.println("获取到的所有参数 <br/>"); Enumeration paramsName = req.getParameterNames(); while(paramsName.hasMoreElements()){ String paramName = (String)paramsName.nextElement(); String[] paramValues = req.getParameterValues(paramName); if(paramValues.length==1){ String paramValue = paramValues[0]; if (paramValue.length()==0) { pw.println("no value"); }else { pw.print(paramValue); } }else{ for (int i = 0; i < paramValues.length; i++) { pw.println(paramValues[i]); } } } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("post"); doGet(req, resp); }}获取cookie值package com.hq.servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class CookieDemo extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //模拟设置cookie for(int i = 0; i<3;i++){ Cookie cookie = new Cookie("session-Cookie-"+i,"Cookie-Value_S"+i); resp.addCookie(cookie); cookie= new Cookie("Persistent-Cookie-"+i, " hello"); cookie.setMaxAge(3600);//时效性 resp.addCookie(cookie); } //设置网页的字符编码格式为gb2312 resp.setContentType("text/html;charset=gb2312"); PrintWriter pw = resp.getWriter(); //2 获取cookie pw.println("获取到cookie"); Cookie[] cookies = req.getCookies(); if(cookies!=null){ Cookie cookie = null; for(int i = 0; i < cookies.length; i++){ cookie= cookies[i]; pw.println("name:"+cookie.getName()+" value:"+cookie.getValue()); } } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("post"); doGet(req, resp); }}关于Session/** * * session是存在服务器端的，cookie是存在客户端的。 * session可与浏览器关联，每个窗口有独一无二的sessionId.session就是服务端的一个内存，能存储任何内容。键值对 * session是针对窗口的。不像cookie拥有路径访问问题，同一个application下的servlet/jsp可以共享一个session。需要同一个客户端窗口 * * 如果浏览器支持cookie,创建session时会把sessionId保存在cookie里，保持不变。否则sessionId每次都说新生成的 * * session实现： cookie实现、url重写实现 * * * cookie(临时的，写在文件里)实现：sessionId存在临时cookie里 * 使用url重写的方式实现session，response。encodeURL()，转码，url后面添加sessionId * *http://blog.csdn.net/robbyo/article/details/17733743 */public class SessionDemo extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //获取当前的session,若无，就创建一个session HttpSession mySession = req.getSession(true); resp.setContentType("text/html"); PrintWriter out= resp.getWriter(); String heading; Integer accessCount = (Integer)mySession.getAttribute("accessCount"); if(accessCount==null){ accessCount = new Integer(0); heading="welcome,new comer"; }else{ heading="welcome back"; accessCount = new Integer(accessCount.intValue()+1); } mySession.setAttribute("accessCount", accessCount); out.println("<H3>show info saved in session</H3>"+accessCount); out.println("<H3>create Information</H3>"); out.println(" new Session:"+mySession.isNew()); out.println("session id:"+mySession.getId()+ ",create time:"+mySession.getCreationTime() //最近一次访问的时间，session是有过期时间的 +",last access time:"+mySession.getLastAccessedTime()); out.println("<H3>Request Information</H3>"); out.println("Session ID from Request: " //上次使用的session + req.getRequestedSessionId()); out.println("<BR>Session ID via Cookie: " //方式1：通过cookie + req.isRequestedSessionIdFromCookie()); out.println("<BR>Session ID via rewritten URL: " //方式2：通过重写url + req.isRequestedSessionIdFromURL()); out.println("<BR>Valid Session ID: " //session是否有效 + req.isRequestedSessionIdValid()); //添加了一个刷新,浏览器不使用cookie，就在url里面添加session out.println("<a href="+"SessionDemo"+">simple url </a>"); //经测试，360不行，Chrome可以.response.encodeURL的功能是url后添加session。 String urlWithSession = resp.encodeURL("SessionDemo"); out.println("<a href='"+urlWithSession+"'>url with session</a>"); out.close(); // close output stream } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("post"); doGet(req, resp); }}application/** * application里面的值是共享的 * @author dell * */public class TestServletContext extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html;charset=gb2312"); PrintWriter out = resp.getWriter(); //获取application ServletContext application = this.getServletContext(); //设置application里的内容 Integer accessCount = (Integer)application.getAttribute("accessCount"); if(accessCount==null){ accessCount = new Integer(0); }else{ accessCount = new Integer(accessCount.intValue()+1); } application.setAttribute("accessCount", accessCount); //获取application里的内容 out.println("get count:"+accessCount); }}新闻热点
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