J2EE Servlet 学习笔记

<?xml version="1.0" encoding="ISO-8859-1"?><web-app xmlns="http://java.sun.com/xml/ns/javaee"   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"   version="2.5">       <servlet><servlet-name>HelloWorldServlet</servlet-name><servlet-class>org.laotou99.abc.servlet.HelloWorldServlet</servlet-class>   </servlet>         <servlet-mapping><servlet-name>HelloWorldServlet</servlet-name><url-pattern>/helloworld</url-pattern>   </servlet-mapping>      <servlet><servlet-name>WelcomeServlet</servlet-name><servlet-class>org.laotou99.abc.servlet.WelcomeServlet</servlet-class><init-param><param-name>greeting</param-name><param-value>Welcome you</param-value></init-param>   </servlet>      <servlet-mapping><servlet-name>WelcomeServlet</servlet-name><url-pattern>/welcome</url-pattern>   </servlet-mapping>      <servlet><servlet-name>OutputInfoServlet</servlet-name><servlet-class>org.laotou99.abc.servlet.OutputInfoServlet</servlet-class>   </servlet>      <servlet-mapping><servlet-name>OutputInfoServlet</servlet-name><url-pattern>/info</url-pattern>   </servlet-mapping>      <servlet><servlet-name>LoginServlet</servlet-name><servlet-class>org.laotou99.abc.servlet.LoginServlet</servlet-class>   </servlet>      <servlet-mapping><servlet-name>LoginServlet</servlet-name><url-pattern>/login</url-pattern>   </servlet-mapping>      <servlet><servlet-name>CounterServlet</servlet-name><servlet-class>org.laotou99.abc.servlet.CounterServlet</servlet-class>   </servlet>          <servlet-mapping><servlet-name>CounterServlet</servlet-name><url-pattern>/product.html</url-pattern>   </servlet-mapping>       <servlet><servlet-name>PortalServlet</servlet-name><servlet-class>org.laotou99.abc.servlet.PortalServlet</servlet-class>   </servlet>      <servlet-mapping><servlet-name>PortalServlet</servlet-name><url-pattern>/portal</url-pattern>   </servlet-mapping>      <servlet><servlet-name>LoginServlet2</servlet-name><servlet-class>org.laotou99.abc.servlet.LoginServlet2</servlet-class>   </servlet>      <servlet-mapping><servlet-name>LoginServlet2</servlet-name><url-pattern>/login2</url-pattern>   </servlet-mapping>          </web-app>

package org.laotou99.abc.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//javac -d ..\WEB-INF\classes LoginServlet.javapublic class LoginServlet extends HttpServlet{public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{resp.setContentType("text/html;charset=gb2312");String name = req.getParameter("username");String pwd =  req.getParameter("password");if(name!=null && pwd!=null && name.equals("gjj") && pwd.equals("123")){resp.sendRedirect("success.html");}else{resp.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,"服务器忙，请稍后再试");}}public void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{doGet(req,resp);}}

package org.laotou99.abc.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;//javac -d ..\WEB-INF\classes LoginServlet2.javapublic class LoginServlet2 extends HttpServlet{public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{resp.setContentType("text/html;charset=gb2312");PrintWriter out = resp.getWriter();out.println("<form method=post action=portal>");out.println("<table>");out.println("<tr>");out.println("<td>请输入用户名</td>");out.println("<td><input type=text name=username></td>");out.println("</tr>");out.println("<tr>");out.println("<td>请输入密码</td>");out.println("<td><input type=password name=password></td>");out.println("</tr>");out.println("<tr>");out.println("<td><input type=reset value=重置></td>");out.println("<td><input type=submit value=登入></td>");out.println("</tr>");out.println("</table>");out.println("</form>");out.close();}public void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{doGet(req,resp);}}

package org.laotou99.abc.servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//javac -d ..\WEB-INF\classes OutputInfoServlet.javapublic class OutputInfoServlet extends HttpServlet{public void doGet(HttpServletRequest req,HttpServletResponse resp)throws  ServletException, IOException{resp.setContentType("text/html;charset=gb2312");PrintWriter out = resp.getWriter();Enumeration headNames = req.getHeaderNames();out.println("<html><head>");out.println("<title>Info Page</title>");out.println("</head>");out.println("<body><center>");out.println("<table border=1 align=center>");out.println("<caption>Servlet 接收到HTTP消息报头的信息</caption>");out.println("<tr bgcolor=#999999>");out.println("<th>消息报头的名字</th>");out.println("<th>消息报头的值</th>");out.println("</tr>");while(headNames.hasMoreElements()){String name = (String)headNames.nextElement();String value = req.getHeader(name);out.println("<tr>");out.println("<td>"+ name +"</td>");out.println("<td>"+ value +"</td>");out.println("</tr>");}out.println("</table><p>");out.println("<table border=1 align=center");out.println("<caption>其他访问信息</caption>");out.println("<tr>");out.println("<td>客户端的IP地址</td>");out.println("<td>"+ req.getRemoteAddr() +"</td>");out.println("</tr>");out.println("<tr>");out.println("<td>客户端的端口号</td>");out.println("<td>"+ req.getRemotePort() +"</td>");out.println("</tr>");out.println("<tr>");out.println("<td>服务器端的IP地址</td>");out.println("<td>"+ req.getLocalAddr() +"</td>");out.println("</tr>");out.println("<tr>");out.println("<td>服务器端的端口号</td>");out.println("<td>"+ req.getLocalPort() +"</td>");out.println("</tr>");out.println("</table>");out.println("</center></body></html>");out.close();}}

package org.laotou99.abc.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.ServletContext;import javax.servlet.RequestDispatcher;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//javac -d ..\WEB-INF\classes PortalServlet.javapublic class PortalServlet extends HttpServlet{public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{resp.setContentType("text/html;charset=gb2312");PrintWriter out = resp.getWriter();out.println("<html><head><title>");out.println("登入页面");out.println("</title></head></html>");String name = req.getParameter("username");String pwd = req.getParameter("password");ServletContext context = getServletContext();if("gjj".equals(name) && "123".equals(pwd)){RequestDispatcher rd = context.getRequestDispatcher("/welcome");rd.forward(req,resp);}else{RequestDispatcher rd = context.getRequestDispatcher("/login2");rd.forward(req,resp);}out.println("</body></html>");out.close();}public void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{doGet(req,resp);}}

package org.laotou99.abc.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.Servlet;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;//javac -d . HelloWorldServlet.javapublic class HelloWorldServlet implements Servlet{private ServletConfig config;public void destroy(){}public ServletConfig getServletConfig(){return config;}public String getServletInfo(){return null;}public void init(ServletConfig config)throws ServletException{this.config = config;}public void service(ServletRequest req, ServletResponse res)throws ServletException, IOException{PrintWriter out = res.getWriter();out.println("Hello world222");out.close();}}

package org.laotou99.abc.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;//javac -d ..\WEB-INF\classes CounterServlet.javapublic class CounterServlet extends HttpServlet{public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{ServletContext context = getServletContext();Integer count = null;synchronized(context){count=(Integer)context.getAttribute("counter");if(null==count){count=new Integer(1);}else{count=new Integer(count.intValue() + 1);}context.setAttribute("counter",count);}resp.setContentType("text/html;charset=gb2312");PrintWriter out = resp.getWriter();out.println("<html><head>");out.println("<title>页面访问统计</title>");out.println("</head><body>");out.println("该页面已被访问了"+"<b>"+count+"</b>"+"次");out.println("</body></html>");out.close();}}

package org.laotou99.abc.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;//javac -d ..\WEB-INF\classes WelcomeServlet.javapublic class WelcomeServlet extends HttpServlet{private String greeting;public void init(){greeting=getInitParameter("greeting");}//C:\Tomcat6\lib\servlet-api.jarpublic void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{  //setCharacterEncoding//req.setCharacterEncoding("gb2312");String username = req.getParameter("username");String welcomeInfo=greeting + ", " +username;resp.setContentType("text/html");PrintWriter out=resp.getWriter();out.println("<html><head><title>");out.println("Welcome Page");out.println("</title></head>");out.println("<body>");out.println(welcomeInfo);out.println("</body></html>");out.close();}public void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{doGet(req,resp);}}

<html><head><title>登入页面</title></head><body><form action="login" method="post"><table><tr><td> 请输入用户名</td><td><input type="text" name="username"> </td></tr><tr><td> 请输入密码</td><td><input type="password" name="password"> </td></tr><tr><td><input type="reset" value="重置"> </td><td><input type="submit" value="登入"> </td></tr></table></form></body></html>

<html><head><title>welcome</title></head><body><form action="welcome" method="post">input username:<input type="text" name="username"><br><input type="submit" value="SUB POST"></form></body></html>
<html><head><title>登入页面</title></head><body>登入成功</body></html>