一:拦截器 :是在面向切面编程的就是在你的service或者一个方法,前调用一个方法,或者在方法后调用一个方法比如动态代理就是拦截器的简单实现,
在你调用方 法前打印出字符串(或者做其它业务逻辑的操作),也可以在你调用方法后打印出字符串,甚至在你抛出异常的时候做业务逻辑的操作。
1.Struts2拦截器是在访问某个Action或Action的某个方法,字段之前或之后实施拦截,并且Struts2拦截器是可插拔的,拦截器是AOP的一种实现。package com.lzw.struts.Interceptor; import com.opensymphony.xwork2.ActionInvocation; import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor; public class MyInterceptor extends MethodFilterInterceptor { private static final long serialVersionUID = -6410044851077844880L; /** * 在struts.xml <param name="lzw">struts</param> */ private String lzw; public String getLzw() { return lzw; } public void setLzw(String lzw) { this.lzw = lzw; } @Override public void destroy() { System.out.println("destroy!"); } @Override public void init() { System.out.println("init!"); } @Override protected String doIntercept(ActionInvocation invocation) throws Exception { System.out.println("MyInterceptor-start"); System.out.println(lzw); String result = invocation.invoke(); System.out.println("MyInterceptor-end"); return result; } }
package com.lzw.struts.Interceptor; import com.opensymphony.xwork2.ActionInvocation; import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor; public class FirstInterceptor extends MethodFilterInterceptor { private static final long serialVersionUID = 1L; @Override protected String doIntercept(ActionInvocation invocation) throws Exception { System.out.println("FirstInterceptor-Start"); String result = invocation.invoke(); System.out.println("FirstInterceptor-End"); return result; } }struts.xml
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" "http://struts.apache.org/dtds/struts-2.3.dtd"> <struts> <!--开发模式开关,本地可以设为true帮助调试问题,部署到服务器上设为false--> <constant name="struts.devMode" value="false"/> <!--务必配上该属性,否则会导致AOP注入异常--> <constant name="struts.objectFactory.spring.autoWire.alwaysRespect" value="true"/> <constant name="struts.i18n.encoding" value="UTF-8" /> <constant name="struts.multipart.maxSize" value="1000000000"/> <package name="strutsLzw" extends="struts-default" namespace="/"> <interceptors> <interceptor name="lzwInterceptorA" class="com.lzw.struts.Interceptor.MyInterceptor"> <param name="lzw">struts</param> </interceptor> <interceptor name="lzwInterceptorB" class="com.lzw.struts.Interceptor.FirstInterceptor"> </interceptor> <!-- 定义自己的拦截器栈 --> <interceptor-stack name="myStack"> <interceptor-ref name="lzwInterceptorA"></interceptor-ref> <interceptor-ref name="lzwInterceptorB"></interceptor-ref> <interceptor-ref name="defaultStack"></interceptor-ref> </interceptor-stack> </interceptors> <!-- 全局的每个action都会拦截 --> <default-interceptor-ref name="myStack"></default-interceptor-ref> <!-- 增加method="lzwTest" 执行LoginAction的lzwTest方法 否则执行execute方法 --> <action name="login" class="com.lzw.struts.action.LoginAction" method="lzwTest"> <result name="success">/result.jsp</result> <result name="failer">/error.jsp</result> <result name="input">/error.jsp</result> </action> </package> </struts>或者:
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" "http://struts.apache.org/dtds/struts-2.3.dtd"> <struts> <package name="strutsLzw" extends="struts-default"> <interceptors> <interceptor name="lzwInterceptor" class="com.lzw.struts.Interceptor.MyInterceptor"> <param name="lzw">struts</param> </interceptor> </interceptors> <!-- 增加method="lzwTest" 执行LoginAction的lzwTest方法 否则执行execute方法 --> <action name="login" class="com.lzw.struts.action.LoginAction" method="lzwTest"> <result name="success">/result.jsp</result> <result name="failer">/error.jsp</result> <result name="input">/error.jsp</result> <interceptor-ref name="lzwInterceptor"></interceptor-ref> <!--增加defaultStack 否则 验证拦截器不执行,也就是 validate 方法不执行--> <interceptor-ref name="defaultStack"></interceptor-ref> </action> </package> </struts>web.xml中加入:
<filter> <filter-name>struts2</filter-name> <!-- 已经过时了<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> --> <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class> <init-param> <param-name>actionPackages</param-name> <param-value>com.lzw.struts.action</param-value> </init-param> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
package com.lzw.struts.action; import com.opensymphony.xwork2.ActionSupport; public class LoginAction extends ActionSupport{ private static final long serialVersionUID = 1L; private String username; private String password; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @Override public String execute() throws Exception { System.out.println("=====execute====="); if ("hello".equals(this.getUsername().trim()) && "world".equals(this.getPassword().trim())) { return "success"; } else { this.addFieldError("username", "username or password error"); return "failer"; } } @Override public void validate() { System.out.println("=====validate====="); if (null == this.getUsername() || "".equals(this.getUsername().trim())) { this.addFieldError("username", "username required"); } if (null == this.getPassword() || "".equals(this.getPassword().trim())) { this.addFieldError("password", "password required"); } } public String lzwTest() { System.out.println("======Test===="); return SUCCESS; } }
<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP 'login.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <form action="login.action" method="post"> username:<input type="text" name="username"><br> password:<input type="password" name="password"><br> <input type="submit" value="submit"> </form> </body> </html>
init! 2013-10-31 13:51:15 org.apache.coyote.AbstractProtocol start 信息: Starting ProtocolHandler ["http-apr-8080"] 2013-10-31 13:51:15 org.apache.coyote.AbstractProtocol start 信息: Starting ProtocolHandler ["ajp-apr-8009"] 2013-10-31 13:51:15 org.apache.catalina.startup.Catalina start 信息: Server startup in 1699 ms MyInterceptor-start struts FirstInterceptor-Start =====validate===== ======Test==== FirstInterceptor-End MyInterceptor-end二: 过滤器:是在java web中,你传入的request,response提前过滤掉一些信息,或者提前设置一些参数,
package com.lzw.filter.demo; 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.HttpSession; public class UserAccessFilter implements Filter{ @Override public void destroy() { System.out.println("destroy!"); } @Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest)req; HttpServletResponse response = (HttpServletResponse)res; HttpSession session = request.getSession(); if(session.getAttribute("user")== null && request.getRequestURI().indexOf("login.jsp")==-1 ){ response.sendRedirect("login.jsp"); return ; } chain.doFilter(req, res); } @Override public void init(FilterConfig config) throws ServletException { //ApplicationFilterConfig[name=UserFilter, filterClass=com.lzw.filter.demo.UserAccessFilter] System.out.println(config.toString()); } }
<filter> <filter-name>UserFilter</filter-name> <filter-class>com.lzw.filter.demo.UserAccessFilter</filter-class> </filter> <filter-mapping> <filter-name>UserFilter</filter-name> <url-pattern>/jsp/*</url-pattern> </filter-mapping>
package com.lzw.filter.demo; import javax.servlet.ServletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; public class InitDataListener implements ServletContextListener { private static ServletContext servletContext; public static ServletContext getServletContext() { return servletContext; } @Override public void contextInitialized(ServletContextEvent contextEvent) { servletContext = contextEvent.getServletContext(); //final ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(servletContext); System.out.println("服务器启动完毕!"); System.out.println(servletContext); } @Override public void contextDestroyed(ServletContextEvent sce) {} }web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <listener> <listener-class>com.lzw.filter.demo.InitDataListener</listener-class> </listener> </web-app>
信息: Starting service Catalina 2013-10-31 15:13:55 org.apache.catalina.core.StandardEngine startInternal 信息: Starting Servlet Engine: Apache Tomcat/7.0.42 服务器启动完毕! org.apache.catalina.core.ApplicationContextFacade@7966340c 2013-10-31 15:13:56 org.apache.coyote.AbstractProtocol start 信息: Starting ProtocolHandler ["http-apr-8080"] 2013-10-31 15:13:56 org.apache.coyote.AbstractProtocol start 信息: Starting ProtocolHandler ["ajp-apr-8009"] 2013-10-31 15:13:56 org.apache.catalina.startup.Catalina start 信息: Server startup in 402 ms