一、ServletConfig

作用

• ServletConfig对象代表的是当前Servlet的配置信息
• ServletConfig对象在初始化期间将信息传递给 servlet

常用方法

package com.itheima.web.servlet;

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

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

//演示ServletConfig对象的方法
public class DServlet implements Servlet {

	public DServlet() {
	}

	@Override
	public void init(ServletConfig config) throws ServletException {

		// 获得ServletContext对象
		ServletContext servletContext = config.getServletContext();
		System.out.println(servletContext);

		// 获得初始化参数值
		String username = config.getInitParameter("username");
		System.out.println(username);

		// 获得web.xml文件中配置的Servlet名称
		String servletName = config.getServletName();
		System.out.println(servletName);

		// 获得所有的初始化参数的名称
		Enumeration<String> initParameterNames = config.getInitParameterNames();
		while (initParameterNames.hasMoreElements()) {
			String name = (String) initParameterNames.nextElement();
			String value = config.getInitParameter(name);
			System.out.println(name+"\t"+value);
		}

	}

	@Override
	public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
	}

	@Override
	public void destroy() {
	}

	@Override
	public ServletConfig getServletConfig() {
		return null;
	}

	@Override
	public String getServletInfo() {
		return null;
	}

}

二、ServletContext