使用Filter现实统一全站编码；Listener监听器

于 2021-12-26 16:17:52 发布
阅读量1.2k 收藏 2
点赞数 1
文章标签： 服务器 html java
版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。
本文链接：https://blog.youkuaiyun.com/qq_55680233/article/details/122156137
版权
本文详细介绍了如何使用Filter实现全站编码的统一，从创建form.jsp页面到编写CharacterServlet，再到创建CharacterFilter过滤器，以及配置映射信息。同时，文章还探讨了Listener监听器的使用，包括创建MyListener类，实现多个监听器接口，并在web.xml中配置，以及测试监听超时和域对象属性变更的示例。

摘要生成于 C知道 ，由 DeepSeek-R1 满血版支持， 前往体验 >

一：使用Filter现实统一全站编码
1.编写一个form.jsp页面，该页面用于提交用户是表单信息
form.jsp:

<%@ page language="java" contentType="text/html; charset=utf-8"
	pageEncoding="utf-8" import="java.util.*"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<center>
	<h3>用户登录</h3>
</center>
<body style="text-align: center;">
	<a href="<%=request.getContextPath()%>/CharacterServlet?name=传智播客&password=123456">单击超链接登录</a>
	<form action="<%=request.getContextPath()%>/CharacterServlet"
		method="post">
		<table border="1" width="600px" cellpadding="0" cellspacing="0"
			align="center">
			<tr>
				<td height="30" align="center">用户名：</td>
				<td>&nbsp;<input type="text" name="name" />
				</td>
			</tr>
			<tr>
				<td height="30" align="center">密 &nbsp; 码：</td>
				<td>&nbsp;<input type="password" name="password" />
				</td>
			</tr>
			<tr>
				<td height="30" colspan="2" align="center">
				<input type="submit" value="登录" />
				 &nbsp;&nbsp;&nbsp;&nbsp;
				<input type="reset" value="重置" />
			    </td>
			</tr>
		</table>
	</form>
</body>

2.创建Servlet
编写一个CharacterServlet类，该类用于获取用户输入的的请求参数，并将参数输出到控制台

package cn.itcast.chapter08.filter;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
public class CharacterServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		System.out.println(request.getParameter("name"));
		System.out.println(request.getParameter("password"));
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}

3.创建过滤器
在chapter08项目的 cn itcast chapter08.fiter包中，编写一个 CharacterFilter 类用于拦载用户的请求问。实现统一全站编码的功能。只是针对请求的方式不同，科次乱码的方式也不柜同。 可以通过 HitpServletRequestWrapDer 类对HitpServletRequest类进行包装，通过重与get Parameter()的方式来设置GET方式提交参数的编码，
CharacterFilter.java

package cn.itcast.chapter08.filter;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class CharacterFilter implements Filter {
	public void init(FilterConfig filterConfig) throws ServletException {
	}
	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) resp;
		// 拦截所有的请求 解决全站中文乱码
		// 指定 request 和 response 的编码
		request.setCharacterEncoding("utf-8"); // 只对消息体有效
		response.setContentType("text/html;charset=utf-8");
		// 对request进行包装
		CharacterRequest characterRequest = new CharacterRequest(request);
		chain.doFilter(characterRequest, response);
	}
	public void destroy() {
	}
}
// 继承 默认包装类HttpServletRequestWrapper
class CharacterRequest extends HttpServletRequestWrapper {
	private HttpServletRequest request;
	public CharacterRequest(HttpServletRequest request) {
		super(request);
		this.request = request;
	}
	// 子类继承父类一定会覆写一些方法，此处用于重写getParamter()方法
	public String getParameter(String name) {
		// 调用被包装对象的getParameter()方法，获得请求参数
		String value = super.getParameter(name);
		if (value == null)
			return null;
		// 判断请求方式
		String method = super.getMethod();
		if ("get".equalsIgnoreCase(method)) {
			try {
					value = new String(value.getBytes("iso-8859-1"), "utf-8");
			} catch (UnsupportedEncodingException e) {
				throw new RuntimeException(e);
			}
		}
		// 解决乱码后返回结果
		return value;
	}
}

4.配置映射信息

<servlet>
		<description></description>
		<display-name>CharacterServlet</display-name>
		<servlet-name>CharacterServlet</servlet-name>
		<servlet-class>cn.itcast.chapter08.filter.CharacterServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>CharacterServlet</servlet-name>
		<url-pattern>/CharacterServlet</url-pattern>
	</servlet-mapping>
	<filter>
		<filter-name>CharacterFilter</filter-name>
		<filter-class>cn.itcast.chapter08.filter.CharacterFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>CharacterFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

5.测试结果：
请添加图片描述
二Listener监听器
1.创建监听器
编写一个MyListener类，用来实现多个监听器接口
MyListener.java

package chapter11.listener;
 
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
 
/**
 * Application Lifecycle Listener implementation class mylistener
 *
 */
@WebListener
public class mylistener implements ServletContextListener, HttpSessionListener, ServletRequestListener {
 
    /**
     * Default constructor. 
     */
 
	/**
     * @see HttpSessionListener#sessionCreated(HttpSessionEvent)
     */
    public void sessionCreated(HttpSessionEvent arg0)  { 
         // TODO Auto-generated method stub
    	System.out.println("servletsession被创建了");
    }
 
	/**
     * @see ServletRequestListener#requestDestroyed(ServletRequestEvent)
     */
    public void requestDestroyed(ServletRequestEvent arg0)  { 
         // TODO Auto-generated method stub
    	System.out.println("servletrequest被销毁了");
    }
 
	/**
     * @see ServletRequestListener#requestInitialized(ServletRequestEvent)
     */
    public void requestInitialized(ServletRequestEvent arg0)  { 
         // TODO Auto-generated method stub
    	System.out.println("servletrequest被创建了");
    }
 
	/**
     * @see HttpSessionListener#sessionDestroyed(HttpSessionEvent)
     */
    public void sessionDestroyed(HttpSessionEvent arg0)  { 
         // TODO Auto-generated method stub
    	System.out.println("servletsession被销毁了");
    }
 
	/**
     * @see ServletContextListener#contextDestroyed(ServletContextEvent)
     */
    public void contextDestroyed(ServletContextEvent arg0)  { 
         // TODO Auto-generated method stub
    	System.out.println("servletcontext被销毁了");
    }
 
	/**
     * @see ServletContextListener#contextInitialized(ServletContextEvent)
     */
    public void contextInitialized(ServletContextEvent arg0)  { 
         // TODO Auto-generated method stub
    	System.out.println("servletcontext被创建了");
    }
	
}

2.添加监听器类信息
在web.xml添加

<listener>
  	<listener-class>
  		chapter11.listener.mylistener
  	</listener-class>
  </listener>

3.启动项目
请添加图片描述

4.测试
设置监听超时信息

<session-config>
  	<session-timeout>2</session-timeout>
  </session-config>

请添加图片描述

监听域对象的属性变更
1.创建测试页面
testattribute.jsp

<?xml version="1.0" encoding="UTF-8" ?>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Insert title here</title>
</head>
<body>
	<h3>这是个测试对象属性信息监听器的页面</h3>
	<%
		getServletContext().setAttribute("username", "itcast");
		getServletContext().setAttribute("username", "itheima");
		getServletContext().removeAttribute("username");
		session.setAttribute("username", "itcast");
		session.setAttribute("username", "itheima");
		session.removeAttribute("username");
		request.setAttribute("username", "itcast");
		request.setAttribute("username", "itheima");
		request.removeAttribute("username");
	%>
</body>
</html>

2.创建监听器
MyAttributeListener.java

package chapter11.listener;
 
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.ServletRequestAttributeEvent;
import javax.servlet.ServletRequestAttributeListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
 
/**
 * Application Lifecycle Listener implementation class myattributelistener
 *
 */
@WebListener
public class myattributelistener implements ServletContextAttributeListener, HttpSessionAttributeListener, ServletRequestAttributeListener {
 
    /**
     * Default constructor. 
     */
    public myattributelistener() {
        // TODO Auto-generated constructor stub
    }
 
	/**
     * @see ServletContextAttributeListener#attributeAdded(ServletContextAttributeEvent)
     */
    public void attributeAdded(ServletContextAttributeEvent sae)  { 
         // TODO Auto-generated method stub
    	String name = sae.getName();
    	System.out.println("servletcontext添加属性:"+ name + "="+sae.getServletContext().getAttribute(name));
    }
 
	/**
     * @see ServletContextAttributeListener#attributeRemoved(ServletContextAttributeEvent)
     */
    public void attributeRemoved(ServletContextAttributeEvent sae)  { 
         // TODO Auto-generated method stub
    	String name = sae.getName();
    	System.out.println("servletcontext移除属性:"+name);
    }
 
	/**
     * @see ServletRequestAttributeListener#attributeRemoved(ServletRequestAttributeEvent)
     */
    public void attributeRemoved(ServletRequestAttributeEvent sra)  { 
         // TODO Auto-generated method stub
    	String name = sra.getName();
    	System.out.println("servletrequest移除属性"+name);
    }
 
	/**
     * @see ServletRequestAttributeListener#attributeAdded(ServletRequestAttributeEvent)
     */
    public void attributeAdded(ServletRequestAttributeEvent sra)  { 
         // TODO Auto-generated method stub
    	String name = sra.getName();
    	System.out.println("servletrequest添加属性:"+ name + "="+sra.getServletRequest().getAttribute(name));
    }
 
	/**
     * @see ServletRequestAttributeListener#attributeReplaced(ServletRequestAttributeEvent)
     */
    public void attributeReplaced(ServletRequestAttributeEvent sra)  { 
         // TODO Auto-generated method stub
    	String name = sra.getName();
    	System.out.println("servletrequest替换属性:"+ name + "="+sra.getServletRequest().getAttribute(name));
    	}
 
	/**
     * @see HttpSessionAttributeListener#attributeAdded(HttpSessionBindingEvent)
     */
    public void attributeAdded(HttpSessionBindingEvent hbe)  { 
         // TODO Auto-generated method stub
    	String name = hbe.getName();
    	System.out.println("httpsession添加属性:"+ name + "="+hbe.getSession().getAttribute(name));
    	
    }
 
	/**
     * @see HttpSessionAttributeListener#attributeRemoved(HttpSessionBindingEvent)
     */
    public void attributeRemoved(HttpSessionBindingEvent hbe)  { 
         // TODO Auto-generated method stub
    	String name = hbe.getName();
    	System.out.println("httpsession移除属性:"+name);
    }
 
	/**
     * @see HttpSessionAttributeListener#attributeReplaced(HttpSessionBindingEvent)
     */
    public void attributeReplaced(HttpSessionBindingEvent hbe)  { 
         // TODO Auto-generated method stub
    	String name = hbe.getName();
    	System.out.println("httpsession替换属性:"+ name + "="+hbe.getSession().getAttribute(name));
    }
 
	/**
     * @see ServletContextAttributeListener#attributeReplaced(ServletContextAttributeEvent)
     */
    public void attributeReplaced(ServletContextAttributeEvent sea)  { 
         // TODO Auto-generated method stub
    	String name = sea.getName();
    	System.out.println("servletcontext替换属性:"+ name + "="+sea.getServletContext().getAttribute(name));
    }
	
}

3.添加监听信息（web.xml）

<listener>
  	<listener-class>
  		chapter11.listener.myattributelistener
  	</listener-class>
  </listener>

4.启动项目
请添加图片描述

念、y
关注
评论
添加红包

请填写红包祝福语或标题

个

红包个数最小为10个

元

红包金额最低5元

当前余额3.43元 前往充值 >
需支付：10.00元
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付元
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明：

1.余额是钱包充值的虚拟货币，按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载，可以购买VIP、付费专栏及课程。

余额充值