ServletConfig对象.

• 是什么

  ServletConfig是javax.servlet.包下的一个接口，ServletConfig它是Servlet的一个配置对象；

  ServletConfig是由tomcat容器创建，通过init方法传入给Servlet；

• ServletConfig对象如何获取?

  在GenericServlet里面定义了：

public ServletConfig getServletConfig() {
    return this.config;
}

• 常用方法

getInitParameter(String parameterName); //根据参数名称获取指定的参数值
getInitParameterNames(); //获取所有的参数名称

  在web.xml文件中配置一下：

<servlet>
        <servlet-name>ServletConfigServlet</servlet-name>
        <servlet-class>com.by.servlet.ServletConfigServlet</servlet-class>
        <init-param>
            <param-name>username</param-name>
            <param-value>Tom</param-value>
        </init-param>
        <init-param>
            <param-name>password</param-name>
            <param-value>123</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletConfigServlet</servlet-name>
        <url-pattern>/servletConfigServlet</url-pattern>
    </servlet-mapping>

 在ServletConfigServlet这个类中调用一下：

/*
 * Copyright (c) 2020, 2023,  All rights reserved.
 *
 */
package com.by.servlet;

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

/**
 * <p>Project: JavaWeb-Servlet - ServletConfigServlet</p>
 * <p>Powered by scl On 2023-12-26 15:52:05</p>
 * <p>描述：<p>
 *
 * @author 孙臣龙 [1846080280@qq.com]
 * @version 1.0
 * @since 17
 */
public class ServletConfigServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletConfig servletConfig = getServletConfig();
        String username = servletConfig.getInitParameter("username");
        String password = servletConfig.getInitParameter("password");
        System.out.println(username+password);
    }
}

结果展示：