Java中filter用法完整代码示例

java/149022.html">java;">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  {  }}

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());        }      }    }  }

import javax.servlet.*;import java.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Html Form请求参数的中文问题  */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");	}}

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 {		//记录用户的访问操作		HttpServletRequest request1 = (HttpServletRequest)request;		StringBuffer url = request1.getRequestURL();		//对url进行过滤，如果是js/css/image则不进行处理		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);			}			//保存到数据库中			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){		//将报表任务数据保存到数据库中		Connection conn = null;		Statement st = null;		try {			//构造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;			//表示操作失败		}		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;		//表示操作成功	}}

<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>

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。  		HttpServletRequest request = (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  		HttpServletResponse response = (HttpServletResponse)servletResponse。  		        String currentURL = request.getRequestURI();		//取得根目录所对应的绝对路径:  		String targetURL = currentURL.substring(currentURL.indexOf("/", 1), currentURL.length());		//截取到当前文件名用于比较  		HttpSession session = 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。	}	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>//表示对所有jsp文件有效</filter-mapping>