昨天的一些代码笔记

最新推荐文章于 2025-02-02 18:29:02 发布

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本文介绍了两个Servlet示例：一是通过ServletConfig获取初始化参数并列举所有参数名称；二是通过ServletContext获取上下文初始化参数，并设置HTTP响应头实现页面跳转与自动刷新。

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package cn.itcast.khl.setvlet2;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/Demo4")
public class Demo4 extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		//先获取ServletConfig对象
		ServletConfig config=this.getServletConfig();
		//获取配置文件中的servlet名称
		/*String name=config.getServletName();*/
		//获取初始化参数
		/*String username=config.getInitParameter("username");
		String password=config.getInitParameter("password");
		System.out.println(name+":"+username+":"+password);*/
		
		//获取初始化参数名集合的枚举
		Enumeration e=config.getInitParameterNames();
		while(e.hasMoreElements())
		{
			String name=e.nextElement();
			System.out.println(config.getInitParameter(name));
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		doGet(request, response);
	}

}

package cn.itcast.khl.setvlet2;

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

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/ContextDemo")
public class ContextDemo extends HttpServlet 
{	
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		ServletContext context=getServletContext();
		String encoding=context.getInitParameter("encoding");
		System.out.println("编码："+encoding);
		
		Enumeration e=context.getInitParameterNames();
		while(e.hasMoreElements())
		{
			String name=e.nextElement();
			System.out.println(name+":"+context.getInitParameter(name));
		}
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		doGet(request, response);
	}

}

package cn.itcast.khl.http;

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

@WebServlet("/Demo1")
public class HttpDemo1 extends HttpServlet 
{
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
	    //重定向
		response.setContentType("text/html;charset=utf-8");
		//response.getWriter().write("借钱");
		//告诉服务器你没钱
		response.setStatus(302);
		//告诉我其他可借钱的地址
		response.setHeader("location", "/day09/1.html");
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		doGet(request, response);
	}

}

//控制自动刷新
package cn.itcast.khl.http;

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

@WebServlet("/RefreshDemo")
public class RefreshDemo extends HttpServlet 
{
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		response.setContentType("text/html;charset=utf-8");
		response.getWriter().write("被访问了。。。");
		//页面5秒后跳转
		response.setHeader("refresh", "5;url=/day09/1.html");
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		doGet(request,response);
	}

}