public abstract interface Filter{ public abstract void init(FilterConfig paramFilterConfig) throws ServletException; public abstract void doFilter(ServletRequest paramServletRequest, ServletResponse paramServletResponse, FilterChain paramFilterChain) throws IOException, ServletException; public abstract void destroy(); }
过滤器范例:html
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; /** * @author yangcq * @description 过滤器Filter的工做原理 */ public class FilterTest implements Filter{ public void destroy() { System.out.println("----Filter销毁----"); } public void doFilter(ServletRequest request, ServletResponse response,FilterChain filterChain) throws IOException, ServletException { // 对request、response进行一些预处理 request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); System.out.println("----调用service以前执行一段代码----"); filterChain.doFilter(request, response); // 执行目标资源,放行 System.out.println("----调用service以后执行一段代码----"); } public void init(FilterConfig arg0) throws ServletException { System.out.println("----Filter初始化----"); } }
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <!--配置过滤器--> <filter> <filter-name>FilterTest</filter-name> <filter-class>com.yangcq.filter.FilterTest</filter-class> </filter> <!--映射过滤器--> <filter-mapping> <filter-name>FilterTest</filter-name> <!--“/*”表示拦截全部的请求 --> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
<filter> <filter-name>encodingFilter</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
package org.springframework.web.filter; import java.io.IOException; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.util.ClassUtils; public class CharacterEncodingFilter extends OncePerRequestFilter{ private static final boolean responseSetCharacterEncodingAvailable = ClassUtils.hasMethod( class$javax$servlet$http$HttpServletResponse, "setCharacterEncoding", new Class[] { String.class }); // 须要设置的编码方式,为了支持可配置,Spring把编码方式设置成了一个变量 private String encoding; // 是否强制使用统一编码,也是为了支持可配置 private boolean forceEncoding; // 构造器,在这里,Spring把forceEncoding的值默认设置成了false public CharacterEncodingFilter(){ this.forceEncoding = false; } // encoding/forceEncoding的setter方法 public void setEncoding(String encoding){ this.encoding = encoding; } public void setForceEncoding(boolean forceEncoding){ this.forceEncoding = forceEncoding; } // Spring经过GenericFilterBean抽象类,对Filter接口进行了整合, protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException{ if ((this.encoding != null) && (((this.forceEncoding) || (request.getCharacterEncoding() == null)))) { request.setCharacterEncoding(this.encoding); if ((this.forceEncoding) && (responseSetCharacterEncodingAvailable)) { response.setCharacterEncoding(this.encoding); } } filterChain.doFilter(request, response); } }
import java.io.IOException; import java.util.Enumeration; import javax.servlet.FilterChain; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang.StringUtils; import org.springframework.web.filter.CharacterEncodingFilter; /* * InvalidCharacterFilter:过滤request请求中的非法字符,防止脚本攻击 * InvalidCharacterFilter继承了Spring框架的CharacterEncodingFilter过滤器,固然,咱们也能够本身实现这样一个过滤器 */ public class InvalidCharacterFilter extends CharacterEncodingFilter{ // 须要过滤的非法字符 private static String[] invalidCharacter = new String[]{ "script","select","insert","document","window","function", "delete","update","prompt","alert","create","alter", "drop","iframe","link","where","replace","function","onabort", "onactivate","onafterprint","onafterupdate","onbeforeactivate", "onbeforecopy","onbeforecut","onbeforedeactivateonfocus", "onkeydown","onkeypress","onkeyup","onload", "expression","applet","layer","ilayeditfocus","onbeforepaste", "onbeforeprint","onbeforeunload","onbeforeupdate", "onblur","onbounce","oncellchange","oncontextmenu", "oncontrolselect","oncopy","oncut","ondataavailable", "ondatasetchanged","ondatasetcomplete","ondeactivate", "ondrag","ondrop","onerror","onfilterchange","onfinish","onhelp", "onlayoutcomplete","onlosecapture","onmouse","ote", "onpropertychange","onreadystatechange","onreset","onresize", "onresizeend","onresizestart","onrow","onscroll", "onselect","onstaronsubmit","onunload","IMgsrc","infarction" }; protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException{ String parameterName = null; String parameterValue = null; // 获取请求的参数 @SuppressWarnings("unchecked") Enumeration<String> allParameter = request.getParameterNames(); while(allParameter.hasMoreElements()){ parameterName = allParameter.nextElement(); parameterValue = request.getParameter(parameterName); if(null != parameterValue){ for(String str : invalidCharacter){ if (StringUtils.containsIgnoreCase(parameterValue, str)){ request.setAttribute("errorMessage", "非法字符:" + str); RequestDispatcher requestDispatcher = request.getRequestDispatcher("/error.jsp"); requestDispatcher.forward(request, response); return; } } } } super.doFilterInternal(request, response, filterChain); } }
<filter> <filter-name>InvalidCharacterFilter</filter-name> <filter-class>com.yangcq.filter.InvalidCharacterFilter</filter-class> </filter> <filter-mapping> <filter-name>InvalidCharacterFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
import java.io.IOException; import java.util.Enumeration; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import org.apache.commons.lang.StringUtils; /** * SelfDefineInvalidCharacterFilter:过滤request请求中的非法字符,防止脚本攻击 */ public class SelfDefineInvalidCharacterFilter implements Filter{ public void destroy() { } public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException { String parameterName = null; String parameterValue = null; // 获取请求的参数 @SuppressWarnings("unchecked") Enumeration<String> allParameter = request.getParameterNames(); while(allParameter.hasMoreElements()){ parameterName = allParameter.nextElement(); parameterValue = request.getParameter(parameterName); if(null != parameterValue){ for(String str : invalidCharacter){ if (StringUtils.containsIgnoreCase(parameterValue, str)){ request.setAttribute("errorMessage", "非法字符:" + str); RequestDispatcher requestDispatcher = request.getRequestDispatcher("/error.jsp"); requestDispatcher.forward(request, response); return; } } } } filterChain.doFilter(request, response); // 执行目标资源,放行 } public void init(FilterConfig filterConfig) throws ServletException { } // 须要过滤的非法字符 private static String[] invalidCharacter = new String[]{ "script","select","insert","document","window","function", "delete","update","prompt","alert","create","alter", "drop","iframe","link","where","replace","function","onabort", "onactivate","onafterprint","onafterupdate","onbeforeactivate", "onbeforecopy","onbeforecut","onbeforedeactivateonfocus", "onkeydown","onkeypress","onkeyup","onload", "expression","applet","layer","ilayeditfocus","onbeforepaste", "onbeforeprint","onbeforeunload","onbeforeupdate", "onblur","onbounce","oncellchange","oncontextmenu", "oncontrolselect","oncopy","oncut","ondataavailable", "ondatasetchanged","ondatasetcomplete","ondeactivate", "ondrag","ondrop","onerror","onfilterchange","onfinish","onhelp", "onlayoutcomplete","onlosecapture","onmouse","ote", "onpropertychange","onreadystatechange","onreset","onresize", "onresizeend","onresizestart","onrow","onscroll", "onselect","onstaronsubmit","onunload","IMgsrc","infarction" }; }
<filter> <filter-name>SelfDefineInvalidCharacterFilter</filter-name> <filter-class>com.yangcq.filter.SelfDefineInvalidCharacterFilter</filter-class> </filter> <filter-mapping> <filter-name>SelfDefineInvalidCharacterFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
package com.yangcq.filter; import java.io.IOException; import java.util.Enumeration; 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 FilterTest implements Filter { /* 过滤器初始化 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig) */ @Override public void init(FilterConfig filterConfig) throws ServletException { System.out.println("----过滤器初始化----"); /** * <filter> <filter-name>FilterTest</filter-name> <filter-class>com.yangcq.filter.FilterTest</filter-class> <!--配置FilterTest过滤器的初始化参数--> <init-param> <description>FilterTest</description> <param-name>name</param-name> <param-value>gacl</param-value> </init-param> <init-param> <description>配置FilterTest过滤器的初始化参数</description> <param-name>like</param-name> <param-value>java</param-value> </init-param> </filter> <filter-mapping> <filter-name>FilterDemo02</filter-name> <!--“/*”表示拦截全部的请求 --> <url-pattern>/*</url-pattern> </filter-mapping> */ //获得过滤器的名字 String filterName = filterConfig.getFilterName(); //获得在web.xml文件中配置的初始化参数 String initParam1 = filterConfig.getInitParameter("name"); String initParam2 = filterConfig.getInitParameter("like"); //返回过滤器的全部初始化参数的名字的枚举集合。 Enumeration<String> initParameterNames = filterConfig.getInitParameterNames(); System.out.println(filterName); System.out.println(initParam1); System.out.println(initParam2); while (initParameterNames.hasMoreElements()) { String paramName = (String) initParameterNames.nextElement(); System.out.println(paramName); } } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { System.out.println("FilterDemo02执行前!!!"); chain.doFilter(request, response); //让目标资源执行,放行 System.out.println("FilterDemo02执行后!!!"); } @Override public void destroy() { System.out.println("----过滤器销毁----"); } }
<filter> <description>过滤器名称</description> <filter-name>自定义的名字</filter-name> <filter-class>com.yangcq.filter.FilterTest</filter-class> <!--配置FilterTest过滤器的初始化参数--> <init-param> <description>配置过滤器的初始化参数</description> <param-name>name</param-name> <param-value>gacl</param-value> </init-param> <init-param> <description>配置FilterTest过滤器的初始化参数</description> <param-name>like</param-name> <param-value>java</param-value> </init-param> </filter><description>用于添加描述信息,该元素的内容可为空,<description>能够不配置。 <filter-name>用于为过滤器指定一个名字,该元素的内容不能为空。 <filter-class>元素用于指定过滤器的完整的限定类名。 <init-param>元素用于为过滤器指定初始化参数,它的子元素<param-name>指定参数的名字,<param-value>指定参数的值。在过滤器中, 可使用FilterConfig接口对象来访问初始化参数。若是过滤器不须要指定初始化参数,那么<init-param>元素能够不配置。 6.二、映射Filter 在web.xml文件中注册了Filter以后,还要在web.xml文件中映射Filter <!--映射过滤器--> <filter-mapping> <filter-name>FilterTest</filter-name> <!--“/*”表示拦截全部的请求 --> <url-pattern>/*</url-pattern> </filter-mapping> <filter-mapping>元素用于设置一个 Filter 所负责拦截的资源。一个Filter拦截的资源可经过两种方式来指定:Servlet 名称和资源访问的请求路径 <filter-name>子元素用于设置filter的注册名称。该值必须是在<filter>元素中声明过的过滤器的名字 <url-pattern>设置 filter 所拦截的请求路径(过滤器关联的URL样式) <servlet-name>指定过滤器所拦截的Servlet名称。 <dispatcher>指定过滤器所拦截的资源被 Servlet 容器调用的方式,能够是REQUEST,INCLUDE,FORWARD和ERROR之一,默认REQUEST。用户能够设置多个<dispatcher> 子元素用来指定 Filter 对资源的多种调用方式进行拦截。以下: <filter-mapping> <filter-name>testFilter</filter-name> <url-pattern>/index.jsp</url-pattern> <dispatcher>REQUEST</dispatcher> <dispatcher>FORWARD</dispatcher> </filter-mapping> <dispatcher> 子元素能够设置的值及其意义: REQUEST:当用户直接访问页面时,Web容器将会调用过滤器。若是目标资源是经过RequestDispatcher的include()或forward()方法访问 时,那么该过滤器就不会被调用。 INCLUDE:若是目标资源是经过RequestDispatcher的include()方法访问时,那么该过滤器将被调用。除此以外,该过滤器不会被调用。 FORWARD:若是目标资源是经过RequestDispatcher的forward()方法访问时,那么该过滤器将被调用,除此以外,该过滤器不会被调用。 ERROR:若是目标资源是经过声明式异常处理机制调用时,那么该过滤器将被调用。除此以外,过滤器不会被调用。