一、getInitParameter：

解釋：getInitParameter () 方法是在GenericServlet介面中定義的一個方法 ，用來呼叫初始化在 web.xml中存放的參量。

二、程式碼解釋：

①：附：原始碼！原始碼圖！

package com.laugh.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
 
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class InitServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext Context = this.getServletContext();
        
 
//呼叫初始地址
        String url = Context.getInitParameter("url");
        resp.getWriter().println(url);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

②：web.xml：附：原始碼！原始碼圖！

<?
 
xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <!--我這個頭是新的-->

    <!--設定web初始化引數-->
    <context-param>
        <param-name>url</param-name>
        <param-value>https://www.cnblogs.com/superyonng</param-value>
    </context-param>


    <!--我是提供獲得初始化路徑的方法 InitServlet-->
    <servlet>
        <servlet-name>url</servlet-name>
        <servlet-class>com.laugh.servlet.InitServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>url</servlet-name>
        <url-pattern>/url</url-pattern>
    </servlet-mapping>


</web-app>

③：輸出結果：