2019-05-31 15:13:32 2826浏览
今天千锋扣丁学堂Java培训老师给大家分享一篇关于深入了解Java中Filter过滤器的详细介绍，首先Filter也称之为过滤器，它是Servlet技术中最实用的技术，WEB开发人员通过Filter技术，对web服务器管理的所有web资源：例如Jsp,Servlet,静态图片文件或静态html文件等进行拦截，从而实现一些特殊的功能。例如实现URL级别的权限访问控制、过滤敏感词汇、压缩响应信息等一些高级功能。
public void init(FilterConfig filterConfig) throws ServletException;//初始化
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException;//拦截请求
public void destroy();//销毁
String getFilterName();//得到filter的名称。 String getInitParameter(String name);//返回在部署描述中指定名称的初始化参数的值。如果不存在返回null. Enumeration getInitParameterNames();//返回过滤器的所有初始化参数的名字的枚举集合。 public ServletContext getServletContext();//返回Servlet上下文对象的引用。
<filter> <filter-name>SessionFilter</filter-name> <filter-class>com.action.login.SessionFilter</filter-class> <init-param> <param-name>logonStrings</param-name><!-- 对登录页面不进行过滤 --> <param-value>/project/index.jsp;login.do</param-value> </init-param> <init-param> <param-name>includeStrings</param-name><!-- 只对指定过滤参数后缀进行过滤 --> <param-value>.do;.jsp</param-value> </init-param> <init-param> <param-name>redirectPath</param-name><!-- 未通过跳转到登录界面 --> <param-value>/index.jsp</param-value> </init-param> <init-param> <param-name>disabletestfilter</param-name><!-- Y:过滤无效 --> <param-value>N</param-value> </init-param> </filter> <filter-mapping> <filter-name>SessionFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
package com.action.login;
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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
/**
* 判断用户是否登录,未登录则退出系统
*/
public class SessionFilter implements Filter {
public FilterConfig config;
public void destroy() {
this.config = null;
}
public static boolean isContains(String container, String[] regx) {
boolean result = false;
for (int i = 0; i < regx.length; i++) {
if (container.indexOf(regx[i]) != -1) {
return true;
}
}
return result;
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
HttpServletRequest hrequest = (HttpServletRequest)request;
HttpServletResponseWrapper wrapper = new HttpServletResponseWrapper((HttpServletResponse) response);
String logonStrings = config.getInitParameter("logonStrings"); // 登录登陆页面
String includeStrings = config.getInitParameter("includeStrings"); // 过滤资源后缀参数
String redirectPath = hrequest.getContextPath() + config.getInitParameter("redirectPath");// 没有登陆转向页面
String disabletestfilter = config.getInitParameter("disabletestfilter");// 过滤器是否有效
if (disabletestfilter.toUpperCase().equals("Y")) { // 过滤无效
chain.doFilter(request, response);
return;
}
String[] logonList = logonStrings.split(";");
String[] includeList = includeStrings.split(";");
if (!this.isContains(hrequest.getRequestURI(), includeList)) {// 只对指定过滤参数后缀进行过滤
chain.doFilter(request, response);
return;
}
if (this.isContains(hrequest.getRequestURI(), logonList)) {// 对登录页面不进行过滤
chain.doFilter(request, response);
return;
}
String user = ( String ) hrequest.getSession().getAttribute("useronly");//判断用户是否登录
if (user == null) {
wrapper.sendRedirect(redirectPath);
return;
}else {
chain.doFilter(request, response);
return;
}
}
public void init(FilterConfig filterConfig) throws ServletException {
config = filterConfig;
}
}
<filter> <filter-name>encoding</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name><!--用来指定一个具体的字符集--> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name><!--true：无论request是否指定了字符集，都是用encoding；false：如果request已指定一个字符集，则不使用encoding--> <param-value>false</param-value> </init-param> </filter> <filter-mapping> <filter-name>encoding</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
<filter><!-- lazy loading enabled in spring --> <filter-name>OpenSessionInViewFilter</filter-name> <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class> <init-param> <param-name>sessionFactoryBeanName</param-name><!-- 可缺省。默认是从spring容器中找id为sessionFactory的bean，如果id不为sessionFactory，则需要配置如下，此处SessionFactory为spring容器中的bean。 --> <param-value>sessionFactory</param-value> </init-param> <init-param> <param-name>singleSession</param-name><!-- singleSession默认为true,若设为false则等于没用OpenSessionInView --> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>OpenSessionInViewFilter</filter-name> <url-pattern>*.do</url-pattern> </filter-mapping>
<!-- struts 2.x filter --> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>*.do</url-pattern> </filter-mapping>
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