1、通过web.xml方式

<?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">

	<servlet>
		<servlet-name>Hello07</servlet-name>
		<servlet-class>com.csdn.servlet.InitParamServlet</servlet-class>
		<init-param>
			<param-name>uname</param-name>
			<param-value>我是服务器</param-value>
		</init-param>
	</servlet>

	<servlet-mapping>
		<servlet-name>Hello07</servlet-name>
		<url-pattern>/h07</url-pattern>
	</servlet-mapping>

</web-app>

package com.csdn.servlet;
import jakarta.servlet.*;
import java.io.IOException;
public class InitParamServlet extends GenericServlet {
    private String uname;
    @Override
    public void init() throws ServletException {
        //ServletConfig - 代表当前Servlet的配置信息
        ServletConfig config = getServletConfig();
        //获取初始化参数
        uname = config.getInitParameter("uname");

    }
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println(uname);
    }
}

 2、通过@WebServlet注解方式

package com.csdn.servlet;
import jakarta.servlet.*;
import jakarta.servlet.annotation.WebInitParam;
import jakarta.servlet.annotation.WebServlet;
import java.io.IOException;
@WebServlet(urlPatterns = "/h07", initParams = {
        @WebInitParam(name = "uname", value = "我是服务器")
})
public class InitParamServlet extends GenericServlet {

    private String uname;

    @Override
    public void init() throws ServletException {
        //ServletConfig - 代表当前Servlet的配置信息
        ServletConfig config = getServletConfig();
        //获取初始化参数
        uname = config.getInitParameter("uname");
    }

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println(uname);
    }
}