企业级应用Filter字符过滤器

最新推荐文章于 2025-05-27 09:30:00 发布

Saiheon

最新推荐文章于 2025-05-27 09:30:00 发布

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分类专栏： j2ee 文章标签：企业应用 Servlet JavaEE Web XML

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本文介绍了一个自定义的Java Web Filter（MyFilter），该Filter用于设置请求和响应的字符编码为UTF-8，并通过web.xml进行配置。文章详细展示了Filter的实现方式，包括初始化、请求处理及销毁过程。

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package com.ch.xinriu.web;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class MyFilter implements Filter {
	
	private String characterEncoding;//编码方式，配置在web.xml中
	private boolean enabled;//是否用到此Filter

	public void destroy() {
		// TODO Auto-generated method stub
		characterEncoding = null;//销毁时清空资源
		System.out.println("Filter被销毁！");

	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		// TODO Auto-generated method stub
		System.out.println("处理请求");
		if(enabled || characterEncoding != null){ //如果启用Filter
			request.setCharacterEncoding(characterEncoding);
										//设置request的编码方式
			response.setCharacterEncoding(characterEncoding);
										//设置response的编码方式
		}
		   
		//继续将请求传递到下一个处理中（Filter或者JSP或者Servlet）   
		chain.doFilter(request, response);   
		System.out.println("处理响应"); 

	}

	public void init(FilterConfig config) throws ServletException {
		// TODO Auto-generated method stub
		characterEncoding = config.getInitParameter("characterEncoding");
		enabled = "true".equalsIgnoreCase(config.getInitParameter("enabled").trim());//启用
		System.out.println("Filter被初始化"); 

	}

}

web.xml中的代码

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.5" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

	<!-- 字符编码过滤器 -->
  <filter>
  	<filter-name>MyFilter</filter-name>
  	<filter-class>com.ch.xinriu.web.MyFilter</filter-class>
  	<init-param>
  		<param-name>characterEncoding</param-name>
  		<param-value>UTF-8</param-value>
  	</init-param>
  	<init-param>
  		<param-name>enabled</param-name>
  		<param-value>true</param-value>
  	</init-param>
  </filter>
  <filter-mapping>
  	<filter-name>MyFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  <!-- 结束字符编码过滤器 -->
  
  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <init-param>
      <param-name>debug</param-name>
      <param-value>3</param-value>
    </init-param>
    <init-param>
      <param-name>detail</param-name>
      <param-value>3</param-value>
    </init-param>
    <load-on-startup>0</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>