1、依赖jar

servlet-api.jar

2、工程结构

javascript调用jsp自定义变量 jsp自动调用servlet_xml

3、java servlet实现类

package testServlet;

import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ThreeParams extends HttpServlet
{
  public void init(ServletConfig config)
    throws ServletException
  {
    System.out.println("init");
    super.init(config);
  }

  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
  {
    PrintWriter pw = resp.getWriter();
    System.out.println("Param1: " + req.getParameter("param1"));
    System.out.println("Param2: " + req.getParameter("param2"));
    System.out.println("Param3: " + req.getParameter("param3"));
    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");
    super.doPost(req, resp);
  }
}

4、在配置文件中配置servlet

<?xml version="1.0" encoding="ISO-8859-1" ?>

<web-app version="2.4"
    xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
    
    <servlet>
        <servlet-name>ThreeParams</servlet-name>
        <servlet-class>testServlet.ThreeParams</servlet-class>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>ThreeParams</servlet-name>
        <url-pattern>/testServlet/ThreeParams</url-pattern>
    </servlet-mapping>
    
</web-app>



5、在jsp中调用servlet

<%@ page language="java" contentType="text/html; charset=UTF-8"
    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" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=basePath%>">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form id="form1" name="form1" method="get"  action="testServlet/ThreeParams" >
  <table width="343" border="1">
    <tr>
      <td width="92">param1</td>
      <td width="94"><input name="param1" type="text" id="param1" /></td>
    </tr>
    <tr>
      <td>param2</td>
      <td><label><input name="param2" type="text" id="param2" /></label></td>
    </tr>
    <tr>
      <td>param3</td>
      <td><label><input name="param3" type="text" id="param3" /></label></td>
    </tr>
    <tr>
      <td> </td>
      <td><input type="submit" value="提交" /></td>
    </tr>
  </table>
</form>
</body>
</html>