Servlet的配置

今天接触了Servlet，Servlet 是一个 java程序，是在服务器上运行以处理客户端请求并做出响应的程序Servlet是早期最初始的一个版本，慢慢形成jsp.介绍一下Servlet的配置。

案例：web项目WebRoot/WEB-INF/web.xml下

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5"     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">    <!-- 注册servlet -->  <servlet>      <servlet-name>HelloServlet</servlet-name>      <servlet-class>servlet.HelloServlet</servlet-class>      <!-- 初始化参数:由当前servlet管理 -->      <init-param>          <param-name>name</param-name>          <param-value>小明</param-value>      </init-param>  </servlet>    <servlet>    <description>This is the description of my J2EE component</description>    <display-name>This is the display name of my J2EE component</display-name>    <servlet-name>query</servlet-name>    <servlet-class>servlet.query</servlet-class>  </servlet>    <servlet-mapping>    <servlet-name>query</servlet-name>    <url-pattern>/servlet/query</url-pattern>  </servlet-mapping>  <!-- 映射servlet -->  <servlet-mapping>      <servlet-name>HelloServlet</servlet-name>      <url-pattern>/HelloServlet</url-pattern>  </servlet-mapping>      <!-- 上下文参数:由web容器管理 -->  <context-param>      <param-name>name</param-name>      <param-value>admin</param-value>  </context-param>    <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

JAVA代码：

package servlet;import java.io.IOException;import java.io.PRintWriter;import javax.faces.application.Application;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.Httpsession;import com.sun.corba.se.impl.interceptors.PINoOpHandlerImpl;public class HelloServlet extends HttpServlet {        /**     * servlet生命周期     *  1/实例化servlet（web容器实现）     *    使用功能     *    1、初始化工作;此方法只执行一次；在第一次访问sersvlet的时候执行(执行init（）方法体现)     *    2、真正处理客户端请求(执行service()方法)     *    输出响应信息     *    3、关闭web容器；只执行一次；在web容器关闭的售后执行销毁servlet（执行destory()方法）     */        /* (non-Javadoc)     * 重写父类初始化方法     * @see javax.servlet.GenericServlet#init()     */    @Override    public void init() throws ServletException {        // TODO Auto-generated method stub        System.out.println("servlet第一个执行的方法!!!");                //得到servlet初始化        System.out.println("初始化参数："+this.getServletConfig().getInitParameter("name"));                //获取上下文参数        System.out.println("上下文参数:"+this.getServletContext().getInitParameter("name"));    }    /* (non-Javadoc)     * 以GET提交方式提交的请求调用该方法     * 默认不指定提交方式的时候执行该方法     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)     */    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub                            }    /* (non-Javadoc)     * 以POST提交方式提交的请求调用该方法     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)     */    @Override    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        /**         * 处理客户端的请求         */        System.out.println("执行service方法处理请求");                //接收参数        String username = request.getParameter("username");        String passWord = request.getParameter("password");                if(username.equals("admin") && password.equals("123456")){            //相当于jsp页面的session            HttpSession session = request.getSession();                        Application app = (Application) getServletContext();                        request.setAttribute("username", username);            //跳转到成功页面            request.getRequestDispatcher("/success.jsp").forward(request, response);        }                /**         * 响应客户端请求         */        //告诉客户端怎么解释返回的内容        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        out.print("<HTML>");        out.print("<head><title>HelloServlet</title></head>");        out.print("<body>HelloServlet第一个servlet诞生了!!!</body>");        out.print("</HTML>");        out.close();    }        /* (non-Javadoc)     * servlet(销毁方法)     * @see javax.servlet.GenericServlet#destroy()     */    @Override    public void destroy() {        // TODO Auto-generated method stub        System.out.println("销毁servlet!!!");    }            }

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 query extends HttpServlet {    /**     * Constructor of the object.     */    public query() {        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 {        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.print("    This is ");        out.print(this.getClass());        out.println(", using the GET method");        out.println("  </BODY>");        out.println("</HTML>");        out.flush();        out.close();    }    /**     * 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 {        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.print("    This is ");        out.print(this.getClass());        out.println(", using the POST method");        out.println("  </BODY>");        out.println("</HTML>");        out.flush();        out.close();    }    /**     * Initialization of the servlet. <br>     *     * @throws ServletException if an error occurs     */    public void init() throws ServletException {        // Put your code here    }}

JSP代码：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>登录</title>    <meta http-equiv="pragma" content="no-cache">    <meta http-equiv="cache-control" content="no-cache">    <meta http-equiv="expires" content="0">        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">    <meta http-equiv="description" content="This is my page">    <!--    <link rel="stylesheet" type="text/CSS" href="styles.css">    -->  </head>    <body>    <form action="HelloServlet" method="post">        username:<input type="text" name="username" /><br/>        password:<input type="password" name="password" /><br/>        <input type="submit" />    </form>  </body></html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'success.jsp' starting page</title>        <meta http-equiv="pragma" content="no-cache">    <meta http-equiv="cache-control" content="no-cache">    <meta http-equiv="expires" content="0">        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">    <meta http-equiv="description" content="This is my page">    <!--    <link rel="stylesheet" type="text/css" href="styles.css">    -->  </head>    <body>       ${username } 登录成功<br>  </body></html>