filter 过滤器次要应用于前台向后盾传递数据是的过滤操作。
一、使浏览器不缓存页面的过滤器
import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* 用于的使 Browser 不缓存页面的过滤器
*/
public class ForceNoCacheFilter implements Filter {public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException
{((HttpServletResponse) response).setHeader("Cache-Control","no-cache");
((HttpServletResponse) response).setHeader("Pragma","no-cache");
((HttpServletResponse) response).setDateHeader ("Expires", -1);
filterChain.doFilter(request, response);
}
public void destroy()
{ }
public void init(FilterConfig filterConfig) throws ServletException
{}}二、检测用户是否登陆的过滤器
public class CheckLoginFilter implements Filter {
protected FilterConfig filterConfig = null;
private String redirectURL = null;
private List notCheckURLList = new ArrayList();
private String sessionKey = null;
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
HttpSession session = 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);
}
public void destroy()
{notCheckURLList.clear();
}
private boolean checkRequestURIIntNotFilterList(HttpServletRequest request)
{String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());
return notCheckURLList.contains(uri);
}
public void init(FilterConfig filterConfig) throws ServletException
{
this.filterConfig = filterConfig;
redirectURL = filterConfig.getInitParameter("redirectURL");
sessionKey = filterConfig.getInitParameter("checkSessionKey");
String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");
if(notCheckURLListStr != null)
{StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");
notCheckURLList.clear();
while(st.hasMoreTokens())
{notCheckURLList.add(st.nextToken());
}
}
}
}三、字符编码的过滤器
import javax.servlet.*;
import java.io.IOException;
/**
* 用于设置 HTTP 申请字符编码的过滤器，通过过滤器参数 encoding 指明应用何种字符编码, 用于解决 Html Form 申请参数的中文问题
*/
public class CharacterEncodingFilter
implements Filter
{
protected FilterConfig filterConfig = null;
protected String encoding = "";
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException
{if(encoding != null)
servletRequest.setCharacterEncoding(encoding);
filterChain.doFilter(servletRequest, servletResponse);
}
public void destroy()
{
filterConfig = null;
encoding = null;
}
public void init(FilterConfig filterConfig) throws ServletException
{
this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");
}
}四、记录用户的拜访操作器
package com.qwserv.itm.pfl.log.svr;
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 java.text.SimpleDateFormat;
import javax.servlet.http.HttpServletRequest;
import com.qwserv.itm.api.pfl.sm.vo.Person;
import java.sql.*;
import com.qwserv.itm.api.ServiceAccess;
import com.qwserv.itm.util.toolkit.DebugUtil;
public class ObserveFilter implements Filter {protected static DebugUtil log = DebugUtil.getInstances("pfl-log", ObserveFilter.class);
public void destroy() {}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
ServletException {
// 记录用户的拜访操作
HttpServletRequest request1 = (HttpServletRequest)request;
StringBuffer url = request1.getRequestURL();
// 对 url 进行过滤，如果是 js/css/image 则不进行解决
if (judgeFile(url.toString())){String operTime = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").
format(new java.util.Date());
String hostIp = request.getRemoteAddr();
String sessionId = request1.getRequestedSessionId();
String userId = "";
Person person = (Person)request1.getSession().getAttribute("userObj");
if (null != person && null != person.getUser()){userId = person.getUser().getId();}
String queryString = request1.getQueryString();
if (null != queryString) {url.append('?');
url.append(queryString);
}
// 保留到数据库中
saveToDb(userId,hostIp,sessionId,url.toString(),operTime,"");
}
// Pass control on to the next filter
chain.doFilter(request, response);
}
public void init(FilterConfig filterConfig) throws ServletException { }
public Boolean judgeFile(String url){if (url.endsWith(".gif") || url.endsWith(".jpg") || url.endsWith(".png")
|| url.endsWith(".bmp") || url.endsWith(".css") || url.endsWith(".js")
|| url.endsWith(".jsx")){return false;} else {return true;}
}
public int saveToDb(String userId, String hostIp,String sessionId,String url,
String operTime,String desc){
// 将报表工作数据保留到数据库中
Connection conn = null;
Statement st = null;
try {
// 结构 sql 表达式，将数据插入数据库
conn = ServiceAccess.getSystemSupportService().getDefaultConnection();
st = conn.createStatement();
String sql = "insert into LOG_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 = "insert into LOG_OBSERVE_HISTORY(Id,USERID,URL,Detail,SessionID,HostName,StartDate) values(LOG_OBSERVE_SEQ.nextval,'"+
userId + "','" + url + "','" + desc + "','" + sessionId
+ "','" + hostIp + "',TO_DATE('" + operTime
+ "','YYYY-MM-DD HH24:MI:SS'))";
}
st.executeUpdate(sql);
}
catch (Exception e) {e.printStackTrace();
log.error("--------------------The url String is:" + url + "-------------------------------");
return 1;
// 示意操作失败
}
finally {if (null != st)
{
try{st.close();
}
catch(Exception e)
{e.printStackTrace();
}
st = null;
}
if (conn != null) {
try {conn.close();
}
catch (Exception e) {e.printStackTrace();
}
conn = null;
}
}
return 0;
// 示意操作胜利
}
}<filter>
<filter-name>ObserveFilter</filter-name>
<filter-class>com.qwserv.itm.pfl.log.svr.ObserveFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>ObserveFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>五.Filter 避免用户拜访一些未被受权的资源
package com.drp.util.filter;
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 AuthFilter implements Filter {public void destroy() { }
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
FilterChain filterChain) throws IOException, ServletException {
//1,doFilter 办法的第一个参数为 ServletRequest 对象。此对象给过滤器提供了对进入的信息（包含表单数据、cookie 和 HTTP 申请头）的齐全拜访。第二个参数为 ServletResponse，通常在简略的过滤器中疏忽此参数。最初一个参数为 FilterChain，此参数用来调用 servlet 或 JSP 页。HttpServletRequest request = (HttpServletRequest)servletRequest;
//;// 如果解决 HTTP 申请，并且须要拜访诸如 getHeader 或 getCookies 等在 ServletRequest 中无奈失去的办法，就要把此 request 对象结构成 HttpServletRequest
HttpServletResponse response = (HttpServletResponse)servletResponse。String currentURL = request.getRequestURI();
// 获得根目录所对应的绝对路径:
String targetURL = currentURL.substring(currentURL.indexOf("/", 1), currentURL.length());
// 截取到以后文件名用于比拟
HttpSession session = request.getSession(false);
if (!"/login.jsp".equals(targetURL)) {
// 判断当前页是否是重定向当前的登录页面页面，如果是就不做 session 的判断，防止出现死循环
if (session == null || session.getAttribute("user") == null) {
//* 用户登录当前需手动增加 session
System.out.println("request.getContextPath()=" + request.getContextPath());
response.sendRedirect(request.getContextPath() + "/login.jsp");
// 如果 session 为空示意用户没有登录就重定向到 login.jsp 页面
return;
}
}
// 退出 filter 链持续向下执行
filterChain.doFilter(request, response);
//. 调用 FilterChain 对象的 doFilter 办法。Filter 接口的 doFilter 办法取一个 FilterChain 对象作为它的一个参数。在调用此对象的 doFilter 办法时，激活下一个相干的过滤器。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。}
public void init(FilterConfig filterConfig) throws ServletException {}}
<filter>
<filter-name>AuthFilter</filter-name>
<filter-class>com.drp.util.filter.AuthFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>AuthFilter</filter-name>
<url-pattern>*.jsp</url-pattern>// 示意对所有 jsp 文件无效
</filter-mapping>