Java中filter用法完整代码示例
本文研究的主要是Java中filter过滤器的相关用法,具体实现代码如下。
filter过滤器主要使用于前台向后台传递数据是的过滤操作。程度很简单就不说明了,直接给几个已经写好的代码:
一、使浏览器不缓存页面的过滤器
importjavax.servlet.*; importjavax.servlet.http.HttpServletResponse; importjava.io.IOException; /** *用于的使Browser不缓存页面的过滤器 */ publicclassForceNoCacheFilterimplementsFilter{ publicvoiddoFilter(ServletRequestrequest,ServletResponseresponse,FilterChainfilterChain)throwsIOException,ServletException { ((HttpServletResponse)response).setHeader("Cache-Control","no-cache"); ((HttpServletResponse)response).setHeader("Pragma","no-cache"); ((HttpServletResponse)response).setDateHeader("Expires",-1); filterChain.doFilter(request,response); } publicvoiddestroy() { } publicvoidinit(FilterConfigfilterConfig)throwsServletException { } }
二、检测用户是否登陆的过滤器
publicclassCheckLoginFilterimplementsFilter{ protectedFilterConfigfilterConfig=null; privateStringredirectURL=null; privateListnotCheckURLList=newArrayList(); privateStringsessionKey=null; publicvoiddoFilter(ServletRequestservletRequest,ServletResponseservletResponse,FilterChainfilterChain)throwsIOException,ServletException { HttpServletRequestrequest=(HttpServletRequest)servletRequest; HttpServletResponseresponse=(HttpServletResponse)servletResponse; HttpSessionsession=request.getSession(); if(sessionKey==null) { filterChain.doFilter(request,response); return; } if((!checkRequestURIIntNotFilterList(request))&&session.getAttribute(sessionKey)==null) { response.sendRedirect(request.getContextPath()+redirectURL); return; } filterChain.doFilter(servletRequest,servletResponse); } publicvoiddestroy() { notCheckURLList.clear(); } privatebooleancheckRequestURIIntNotFilterList(HttpServletRequestrequest) { Stringuri=request.getServletPath()+(request.getPathInfo()==null?"":request.getPathInfo()); returnnotCheckURLList.contains(uri); } publicvoidinit(FilterConfigfilterConfig)throwsServletException { this.filterConfig=filterConfig; redirectURL=filterConfig.getInitParameter("redirectURL"); sessionKey=filterConfig.getInitParameter("checkSessionKey"); StringnotCheckURLListStr=filterConfig.getInitParameter("notCheckURLList"); if(notCheckURLListStr!=null) { StringTokenizerst=newStringTokenizer(notCheckURLListStr,";"); notCheckURLList.clear(); while(st.hasMoreTokens()) { notCheckURLList.add(st.nextToken()); } } } }
三、字符编码的过滤器
importjavax.servlet.*; importjava.io.IOException; /** *用于设置HTTP请求字符编码的过滤器,通过过滤器参数encoding指明使用何种字符编码,用于处理HtmlForm请求参数的中文问题 */ publicclassCharacterEncodingFilter implementsFilter { protectedFilterConfigfilterConfig=null; protectedStringencoding=""; publicvoiddoFilter(ServletRequestservletRequest,ServletResponseservletResponse,FilterChainfilterChain)throwsIOException,ServletException { if(encoding!=null) servletRequest.setCharacterEncoding(encoding); filterChain.doFilter(servletRequest,servletResponse); } publicvoiddestroy() { filterConfig=null; encoding=null; } publicvoidinit(FilterConfigfilterConfig)throwsServletException { this.filterConfig=filterConfig; this.encoding=filterConfig.getInitParameter("encoding"); } }
四、记录用户的访问操作器
packagecom.qwserv.itm.pfl.log.svr; importjava.io.IOException; importjavax.servlet.Filter; importjavax.servlet.FilterChain; importjavax.servlet.FilterConfig; importjavax.servlet.ServletException; importjavax.servlet.ServletRequest; importjavax.servlet.ServletResponse; importjava.text.SimpleDateFormat; importjavax.servlet.http.HttpServletRequest; importcom.qwserv.itm.api.pfl.sm.vo.Person; importjava.sql.*; importcom.qwserv.itm.api.ServiceAccess; importcom.qwserv.itm.util.toolkit.DebugUtil; publicclassObserveFilterimplementsFilter{ protectedstaticDebugUtillog=DebugUtil.getInstances("pfl-log",ObserveFilter.class); publicvoiddestroy(){ } publicvoiddoFilter(ServletRequestrequest,ServletResponseresponse,FilterChainchain)throwsIOException, ServletException{ //记录用户的访问操作 HttpServletRequestrequest1=(HttpServletRequest)request; StringBufferurl=request1.getRequestURL(); //对url进行过滤,如果是js/css/image则不进行处理 if(judgeFile(url.toString())){ StringoperTime=newSimpleDateFormat("yyyy-MM-ddHH:mm:ss"). format(newjava.util.Date()); StringhostIp=request.getRemoteAddr(); StringsessionId=request1.getRequestedSessionId(); StringuserId=""; Personperson=(Person)request1.getSession().getAttribute("userObj"); if(null!=person&&null!=person.getUser()){ userId=person.getUser().getId(); } StringqueryString=request1.getQueryString(); if(null!=queryString){ url.append('?'); url.append(queryString); } //保存到数据库中 saveToDb(userId,hostIp,sessionId,url.toString(),operTime,""); } //Passcontrolontothenextfilter chain.doFilter(request,response); } publicvoidinit(FilterConfigfilterConfig)throwsServletException{ } publicBooleanjudgeFile(Stringurl){ if(url.endsWith(".gif")||url.endsWith(".jpg")||url.endsWith(".png") ||url.endsWith(".bmp")||url.endsWith(".css")||url.endsWith(".js") ||url.endsWith(".jsx")){ returnfalse; }else{ returntrue; } } publicintsaveToDb(StringuserId,StringhostIp,StringsessionId,Stringurl, StringoperTime,Stringdesc){ //将报表任务数据保存到数据库中 Connectionconn=null; Statementst=null; try{ //构造sql表达式,将数据插入数据库 conn=ServiceAccess.getSystemSupportService().getDefaultConnection(); st=conn.createStatement(); Stringsql="insertintoLOG_OBSERVE_HISTORY(USERID,URL,Detail,SessionID,HostName,StartDate)values('"+ userId+"','"+url+"','"+desc+"','"+sessionId +"','"+hostIp+"','"+operTime+"')"; if(ServiceAccess.getSystemSupportService().getConnectionType(conn)==ServiceAccess.getSystemSupportService().JCA_TYPE_ORACLE){ sql="insertintoLOG_OBSERVE_HISTORY(Id,USERID,URL,Detail,SessionID,HostName,StartDate)values(LOG_OBSERVE_SEQ.nextval,'"+ userId+"','"+url+"','"+desc+"','"+sessionId +"','"+hostIp+"',TO_DATE('"+operTime +"','YYYY-MM-DDHH24:MI:SS'))"; } st.executeUpdate(sql); } catch(Exceptione){ e.printStackTrace(); log.error("--------------------TheurlStringis:"+url+"-------------------------------"); return1; //表示操作失败 } finally{ if(null!=st) { try{ st.close(); } catch(Exceptione) { e.printStackTrace(); } st=null; } if(conn!=null){ try{ conn.close(); } catch(Exceptione){ e.printStackTrace(); } conn=null; } } return0; //表示操作成功 } }
ObserveFilter com.qwserv.itm.pfl.log.svr.ObserveFilter ObserveFilter /*
五.Filter防止用户访问一些未被授权的资源
packagecom.drp.util.filter; importjava.io.IOException; importjavax.servlet.Filter; importjavax.servlet.FilterChain; importjavax.servlet.FilterConfig; importjavax.servlet.ServletException; importjavax.servlet.ServletRequest; importjavax.servlet.ServletResponse; importjavax.servlet.http.HttpServletRequest; importjavax.servlet.http.HttpServletResponse; importjavax.servlet.http.HttpSession; publicclassAuthFilterimplementsFilter{ publicvoiddestroy(){ } publicvoiddoFilter(ServletRequestservletRequest,ServletResponseservletResponse, FilterChainfilterChain)throwsIOException,ServletException{ //1,doFilter方法的第一个参数为ServletRequest对象。此对象给过滤器提供了对进入的信息(包括表单数据、cookie和HTTP请求头)的完全访问。第二个参数为ServletResponse,通常在简单的过滤器中忽略此参数。最后一个参数为FilterChain,此参数用来调用servlet或JSP页。 HttpServletRequestrequest=(HttpServletRequest)servletRequest; //;//如果处理HTTP请求,并且需要访问诸如getHeader或getCookies等在ServletRequest中无法得到的方法,就要把此request对象构造成HttpServletRequest HttpServletResponseresponse=(HttpServletResponse)servletResponse。 StringcurrentURL=request.getRequestURI(); //取得根目录所对应的绝对路径: StringtargetURL=currentURL.substring(currentURL.indexOf("/",1),currentURL.length()); //截取到当前文件名用于比较 HttpSessionsession=request.getSession(false); if(!"/login.jsp".equals(targetURL)){ //判断当前页是否是重定向以后的登录页面页面,如果是就不做session的判断,防止出现死循环 if(session==null||session.getAttribute("user")==null){ //*用户登录以后需手动添加session System.out.println("request.getContextPath()="+request.getContextPath()); response.sendRedirect(request.getContextPath()+"/login.jsp"); //如果session为空表示用户没有登录就重定向到login.jsp页面 return; } } //加入filter链继续向下执行 filterChain.doFilter(request,response); //.调用FilterChain对象的doFilter方法。Filter接口的doFilter方法取一个FilterChain对象作为它的一个参数。在调用此对象的doFilter方法时,激活下一个相关的过滤器。如果没有另一个过滤器与servlet或JSP页面关联,则servlet或JSP页面被激活。 } publicvoidinit(FilterConfigfilterConfig)throwsServletException{ } }
html
AuthFilter com.drp.util.filter.AuthFilter AuthFilter *.jsp //表示对所有jsp文件有效
总结
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