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Servlet中request.getParameter和getParameterValues getParameterNames三者区别
1.request.getParameter:获取前台表单单个元素name对应的value值
2.request.getParameterValues:获取前台表单多个标签同名name对应的所有value值
3.request.getParameterNames:获取前台表单所有标签元素name的对应的所有value值
例子如下：
先写个allparams.jsp页面
代码语言：javascript复制<%@ 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>My JSP 'allparams.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>
<form action="AllParams" method="POST" target="_blank">
<input type="checkbox" name="habit" value="read">看书
<input type="checkbox" name="habit" value="movie">电影
<input type="checkbox" name="habit" value="game">游戏
<input type="submit" name="submit" value="提交">
</form>
</body>
</html>再写个AllParams.java的servlet程序
代码语言：javascript复制package com.learnservlet.servletexample;
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;
public class AllParams extends HttpServlet {
/**
* Constructor of the object.
*/
public AllParams() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
System.out.println("1.获取前台表单单个元素name对应的value值");
String submitvalue = request.getParameter("submit");
System.out.println(submitvalue);
//相当于获取多个同名复选框的值，放在字符数组中
//相当于 String[] lparamvalues = {value1,value2,value3}
System.out.println("2.获取前台表单多个标签同名name对应的所有value值");
String[] paramvalues = request.getParameterValues("habit");
for(String i:paramvalues){
System.out.println(i);
}
System.out.println("3.获取前台表单所有标签元素name的对应的所有value值");
Enumeration paramNames = request.getParameterNames();
System.out.println(paramNames);//输出枚举对象
while(paramNames.hasMoreElements()){
String paramName = (String)paramNames.nextElement();
String[] paramValue = request.getParameterValues(paramName);
for(String j : paramValue){
System.out.println(j);
}
}
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}Web.xml代码：
代码语言：javascript复制<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
id="WebApp_ID" version="3.1">
<display-name>servletlearn</display-name>
<servlet>
<servlet-name>AllParams</servlet-name>
<servlet-class>com.learnservlet.servletexample.AllParams</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AllParams</servlet-name>
<url-pattern>/AllParams</url-pattern>
</servlet-mapping>
<!-- 默认界面 -->
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>打开游览器：地址栏输入http://localhost:8081/servletlearn/AllParams运行
测试结果如下：
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