JavaWeb---通过ServletConfig获取Servlet的初始化参数

package com.zyz;

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;
import java.util.Enumeration;

/**
 * Created by Administrator on 16-9-29.
 */
public class ConfigServlet extends HttpServlet {
    private ServletConfig config;//此成员变量用来接收ServletConfig对象

    /**
     * 当Servlet配置了初始化参数后，web容器在创建Servlet实例对象时，
     * 会自动将这些初始化参数封装在ServletConfig对象中，并在调用Servlet的
     * init方法时，将ServletConfig对象传给Servlet。进而，程序通过ServletConfig
     * 就可以得到初始化参数信息
     * @param config
     */
    @Override
    public void init(ServletConfig config){
        this.config=config;
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setHeader("Content-Type","text/html;charset=utf8");
        resp.getWriter().write("从web.xml中获取初始化参数<hr>");
        Enumeration<String> paraNames=config.getInitParameterNames();
        /**
         * getInitParameterNames得到的是是枚举类型Enumeration
         *
         */
        while (paraNames.hasMoreElements()){
            String paraName=paraNames.nextElement();
            String paraValue=config.getInitParameter(paraName);
            resp.getWriter().print(paraName+":"+paraValue+"<br>");
        }
    }
}