Servlet入门与实践-优快云博客

本文链接：https://blog.youkuaiyun.com/facepp/article/details/2296319

studyservlet
servlet使用入门
servlet API 包含两个包中,即javax.servlet和javax,servlet.http.
javax.servlet包的主要的类和接口
javax.servlet
接口                  类
ServletConfig         ServletOutputStream
ServletContext         ServletInputStream
ServletResponse        GenericServlet
ServletRequest
Servlet

javax.servlet.http
接口                            类
HttpSession                      Cookie
HttpSessionAttributeListener     HttpServlet
HttpServletRequest
HttpServeltResponse

2实例(源文件见我的空间)
package my.servlet;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

@SuppressWarnings("serial")
public class LoginServlet extends HttpServlet {
    public LoginServlet() {
        try {
            jbInit();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

private static final String CONTENT_TYPE = "text/html; charset=gb2312";

    //Initialize global variables
    public void init() throws ServletException {
    }

    //Process the HTTP Get request
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        response.setContentType(CONTENT_TYPE);
       request.setCharacterEncoding("GBK");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<head><title>Servlet</title></head>");
        out.println("<body bgcolor=/"#ffffff/">");
        String UserId=request.getParameter("userid");
        String PassWord=request.getParameter("password");
        String UserName=request.getParameter("username");
        String Sex=request.getParameter("men");
        String Age=request.getParameter("age");
        out.println("<table border=0 align=center width=50%>");
        out.println("<tr><td colspan=2><center><font color=red size=6>用户注册详细信息</font></center></td></tr>");
        out.println("<tr><td>用户 ID:</td><td><font color=red face=楷体>"+UserId+"</font></td></tr>");
        out.println("<tr><td>密   码:</td><td><font color=red face=宋体>"+PassWord+"</font></td></tr>");
        out.println("<tr><td>姓   名:</td><td><font color=red face=楷体>"+UserName+"</font></td></tr>");
        out.println("<tr><td>性   别:</td><td><font color=red face=宋体>"+Sex+"</font></td></tr>");
        out.println("<tr><td>年   龄:</td><td><font color=red face=宋体>"+Age+"</font></td></tr>");
        out.println("</body>");
        out.println("</html>");
        out.close();
    }

    //Process the HTTP Post request
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        doGet(request, response);
    }

    //Clean up resources
    public void destroy() {
    }

private void jbInit() throws Exception {
}
}

web.xml
添加如下两句话
<servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>my.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/loginservlet</url-pattern>
</servlet-mapping>
使用
index.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=GB2312"%>
<%
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 'index.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">

</head>

<body bgcolor="#ffffff">
<form action="/loginservlet" method="get"> //由于LoginServlet只定义了get方法,这里的method写作get,如果写作post,则取不值
        <table border=0 align=center width=50%>
        <tr><td colspan=2><center><font color=red size=6>用户注册详细信息</font></center></td></tr>
        <tr><td>用户 ID:</td><td><input type="text" name="userid"> </td></tr>
        <tr><td>密   码:</td><td><input type="password" name="password"></td></tr>
        <tr><td>姓   名:</td><td><input type="text" name="username"></td></tr>
        <tr><td>性   别:</td><td><input type="radio" name="men" value="男" checked="checked">男 <input type="radio" name="men" value="女">女</tr>
        <tr><td>年   龄:</td><td><input type="text" name="age"></td></tr>
        <tr><td colspan="2"> <input type="submit" value="注册"></td></tr>
</table>
</form>
</body>
</html>

作业:

1编写一个线程安全的Servlet以便显示该Servlet被访问的次数.
package my.servlet;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;

@SuppressWarnings("serial")
public class LoginServlet extends HttpServlet {
int count;
private static final String CONTENT_TYPE = "text/html; charset=gb2312";
    public LoginServlet() {
        try {
            jbInit();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    //Initialize global variables
    public void init(ServletConfig config) throws ServletException {
    super.init(config);
    String initial=config.getInitParameter("initial");
    try
    {
      count=Integer.parseInt(initial);
    }
    catch(NumberFormatException e)
    {count=0;}
    System.out.println("计数器servlet已经初始化了");
    }

    //Process the HTTP Get request
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {

    count++;
         System.out.println("该servlet的doGet方法被执行了"+count+"次");
    }

    //Process the HTTP Post request
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
    doPost(request, response);
    }

    //Clean up resources
    public void destroy() {
    System.out.println("计数器servlet已经释放资源");
    }

private void jbInit() throws Exception {
}
}

2.编写一个Servlet显示客户的区域信息(包括语言和国家)