Servlet配置初始值，并获取初始值

	<!--配置Servlet的初始化参数  -->
  	<init-param>
  	 	<!-- 初始化参数的名 -->
  		<param-name>username</param-name>
  		 <!-- 初始化参数的名的值 --> 
  		<param-value>root</param-value>
  	</init-param>
  	
  	<init-param>
  		<param-name>password</param-name>
  		<param-value>123456</param-value>
  	</init-param>

	@Override
	public void init(ServletConfig config) throws ServletException {
		System.out.println("init");
		
			String userName = config.getInitParameter("username");//对单个初始值进行获取
		String passWord = config.getInitParameter("password");
		System.out.println("账号："+userName);
		System.out.println("密码："+passWord);
		
		Enumeration<String> names = config.getInitParameterNames();  //获取所有的name属性的名字，并且返回一个集合
		
		while (names.hasMoreElements()) {  //遍历这个集合的所有的name名字
			String name = (String) names.nextElement();
			String value = config.getInitParameter(name); //通过遍历对单个初始值进行获取
			System.out.println("name:"+name+",value:"+value);
		}
		
	}

<?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>JavaWeb_HelloWord</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list> 
  
  <!--配置servlet  -->
  <servlet>
  	<!--Servlet 注册的名字  -->
  	<servlet-name>helloServlet</servlet-name>
  	<!--Servlet 的全类名  -->
  	<servlet-class>com.zhenghui.HelloServlet</servlet-class>
  	
  	<!--配置Servlet的初始化参数  -->
  	<init-param>
  	 	<!-- 初始化参数的名 -->
  		<param-name>username</param-name>
  		 <!-- 初始化参数的名的值 --> 
  		<param-value>root</param-value>
  	</init-param>
  	
  	<init-param>
  		<param-name>password</param-name>
  		<param-value>123456</param-value>
  	</init-param>
  </servlet>
  
   
 <!--映射servlet  -->
  <servlet-mapping> 
    <!--需要和某一个Servlet的servlet-name子节点的文本节点一致  -->
  	<servlet-name>helloServlet</servlet-name>
  	<!--映射具体的访问路径：/代表当前WEB应用的根目录-->
  	<url-pattern>/hello</url-pattern>
  </servlet-mapping>  

</web-app>

package com.zhenghui;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class HelloServlet implements Servlet{

	@Override
	public void destroy() {
		System.out.println("destroy");
	}

	@Override
	public ServletConfig getServletConfig() {
		System.out.println("getServletConfig");
		return null;
	}

	@Override
	public String getServletInfo() {
		System.out.println("getServletInfo");
		return null;
	}

	@Override
	public void init(ServletConfig config) throws ServletException {
		System.out.println("init");
		
		String userName = config.getInitParameter("username");
		String passWord = config.getInitParameter("password");
		System.out.println("账号："+userName);
		System.out.println("密码："+passWord);
		
		Enumeration<String> names = config.getInitParameterNames();
		while (names.hasMoreElements()) {
			String name = (String) names.nextElement();
			String value = config.getInitParameter(name);
			System.out.println("name:"+name+",value:"+value);
		}
		
	}

	@Override
	public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
		System.out.println("service");
	}
	
	public HelloServlet() {
		System.out.println("This is a HelloServlet");
	}

}