Filter之过滤器.docx
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Filter之过滤器.docx
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Filter之过滤器
四个有用的Java过滤器
java代码
一、使浏览器不缓存页面的过滤器
packagecom.sist;
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);
}
}
二、检测用户是否登陆的过滤器
packagecom.sist;
importjavax.servlet.*;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importjavax.servlet.http.HttpSession;
importjava.util.List;
importjava.util.ArrayList;
importjava.util.StringTokenizer;
importjava.io.IOException;
/**
*用于检测用户是否登陆的过滤器,如果未登录,则重定向到指的登录页面
*配置参数checkSessionKey需检查的在Session中保存的关键字
*redirectURL如果用户未登录,则重定向到指定的页面,URL不包括ContextPath
*notCheckURLList不做检查的URL列表,以分号分开,并且URL中不包括ContextPath
*/
publicclassCheckLoginFilterimplementsFilter{
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{
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
packagecom.sist;
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
*/
publicclassCharacterEncodingFilterimplementsFilter{
protectedStringencoding="";
publicvoiddoFilter(ServletRequestservletRequest,
ServletResponseservletResponse,FilterChainfilterChain)
throwsIOException,ServletException{
if(encoding!
=null)
servletRequest.setCharacterEncoding(encoding);
filterChain.doFilter(servletRequest,servletResponse);
}
publicvoiddestroy(){
encoding=null;
}
publicvoidinit(FilterConfigfilterConfig)throwsServletException{
this.encoding=filterConfig.getInitParameter("encoding");
}
}
四、资源保护过滤器
packagecatalog.view.util;
importjavax.servlet.Filter;
importjavax.servlet.FilterConfig;
importjavax.servlet.ServletRequest;
importjavax.servlet.ServletResponse;
importjavax.servlet.FilterChain;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServletRequest;
importjava.io.IOException;
importjava.util.Iterator;
importjava.util.Set;
importjava.util.HashSet;
//
importmons.logging.Log;
importmons.logging.LogFactory;
/**
*ThisFilterclasshandlethesecurityoftheapplication.
*
*Itshouldbeconfiguredinsidetheweb.xml.
*
*@authorDerekY.Shen
*/
publicclassSecurityFilterimplementsFilter{
//theloginpageuri
privatestaticfinalStringLOGIN_PAGE_URI="login.jsf";
//theloggerobject
privateLoglogger=LogFactory.getLog(this.getClass());
//asetofrestrictedresources
privateSetrestrictedResources;
/**
*InitializestheFilter.
*/
publicvoidinit(FilterConfigfilterConfig)throwsServletException{
this.restrictedResources=newHashSet();
this.restrictedResources.add("/createProduct.jsf");
this.restrictedResources.add("/editProduct.jsf");
this.restrictedResources.add("/productList.jsf");
}
/**
*StandarddoFilterobject.
*/
publicvoiddoFilter(ServletRequestreq,ServletResponseres,FilterChainchain)
throwsIOException,ServletException{
this.logger.debug("doFilter");
StringcontextPath=((HttpServletRequest)req).getContextPath();
StringrequestUri=((HttpServletRequest)req).getRequestURI();
this.logger.debug("contextPath="+contextPath);
this.logger.debug("requestUri="+requestUri);
if(this.contains(requestUri,contextPath)&&!
this.authorize((HttpServletRequest)req)){
this.logger.debug("authorizationfailed");
((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req,res);
}
else{
this.logger.debug("authorizationsucceeded");
chain.doFilter(req,res);
}
}
publicvoiddestroy(){}
privatebooleancontains(Stringvalue,StringcontextPath){
Iteratorite=this.restrictedResources.iterator();
while(ite.hasNext()){
StringrestrictedResource=(String)ite.next();
if((contextPath+restrictedResource).equalsIgnoreCase(value)){
returntrue;
}
}
returnfalse;
}
privatebooleanauthorize(HttpServletRequestreq){
//处理用户登录
/*UserBeanuser=(UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);
if(user!
=null&&user.getLoggedIn()){
//userloggedin
returntrue;
}
else{
returnfalse;
}*/
}
}
Servlet过滤器大全
四、资源保护过滤器
packagecatalog.view.util;
importjavax.servlet.Filter;
importjavax.servlet.FilterConfig;
importjavax.servlet.ServletRequest;
importjavax.servlet.ServletResponse;
importjavax.servlet.FilterChain;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServletRequest;
importjava.io.IOException;
importjava.util.Iterator;
importjava.util.Set;
importjava.util.HashSet;
//
importmons.logging.Log;
importmons.logging.LogFactory;
/***//**
*ThisFilterclasshandlethesecurityoftheapplication.
*
*Itshouldbeconfiguredinsidetheweb.xml.
*
*@authorDerekY.Shen
*/
publicclassSecurityFilterimplementsFilter{
//theloginpageuri
privatestaticfinalStringLOGIN_PAGE_URI="login.jsf";
//theloggerobject
privateLoglogger=LogFactory.getLog(this.getClass());
//asetofrestrictedresources
privateSetrestrictedResources;
/***//**
*InitializestheFilter.
*/
publicvoidinit(FilterConfigfilterConfig)throwsServletException{
this.restrictedResources=newHashSet();
this.restrictedResources.add("/createProduct.jsf");
this.restrictedResources.add("/editProduct.jsf");
this.restrictedResources.add("/productList.jsf");
}
/***//**
*StandarddoFilterobject.
*/
publicvoiddoFilter(ServletRequestreq,ServletResponseres,FilterChainchain)
throwsIOException,ServletException{
this.logger.debug("doFilter");
StringcontextPath=((HttpServletRequest)req).getContextPath();
StringrequestUri=((HttpServletRequest)req).getRequestURI();
this.logger.debug("contextPath="+contextPath);
this.logger.debug("requestUri="+requestUri);
if(this.contains(requestUri,contextPath)&&!
this.authorize((HttpServletRequest)req)){
this.logger.debug("authorizationfailed");
((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req,res);
}
else{
this.logger.debug("authorizationsucceeded");
chain.doFilter(req,res);
}
}
publicvoiddestroy(){}
privatebooleancontains(Stringvalue,StringcontextPath){
Iteratorite=this.restrictedResources.iterator();
while(ite.hasNext()){
StringrestrictedResource=(String)ite.next();
if((contextPath+restrictedResource).equalsIgnoreCase(value)){
returntrue;
}
}
returnfalse;
}
privatebooleanauthorize(HttpServletRequestreq){
//处理用户登录
/**//*UserBeanuser=(UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);
if(user!
=null&&user.getLoggedIn()){
//userloggedin
returntrue;
}
else{
returnfalse;
}*/
}
}
五利用Filter限制用户浏览权限
在一个系统中通常有多个权限的用户。
不同权限用户的可以浏览不同的页面。
使用Filter进行判断不仅省下了代码量,而且如果要更改的话只需要在Filter文件里动下就可以。
以下是Filter文件代码:
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;
publicclassRightFilterimplementsFilter{
publicvoiddestroy(){
}
publicvoiddoFilter(ServletRequestsreq,ServletResponsesres,FilterChainarg2)throwsIOException,ServletException{
//获取uri地址
HttpServletRequestrequest=(HttpServletRequest)sreq;
Stringuri=request.getRequestURI();
Stringctx=request.getContextPath();
uri=uri.substring(ctx.length());
//判断admin级别网页的浏览权限
if(uri.startsWith("/admin")){
if(request.getSession().getAttribute("admin")==null){
request.setAttribute("message","您没有这个权限");
request.getRequestDispatcher("/logi
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- Filter 过滤器