getContextPath、getServletPath、getRequestURI的区别

工程图见附件: 
假定你的web application 名称为news,你在浏览器中输入请求路径：  http://localhost:8080/news/main/list.jsp  则执行下面向行代码后打印出如下结果： 
1、 System.out.println(request.getContextPath()); //可返回站点的根路径。也就是项目的名字 
打印结果：/news 
   2、System.out.println(request.getServletPath()); 
打印结果：/main/list.jsp 
3、 System.out.println(request.getRequestURI()); 
打印结果：/news/main/list.jsp 
4、 System.out.println(request.getRealPath("/")); 
打印结果：F:\Tomcat 6.0\webapps\news\test 

======

应该再给个例子如何统计页面访问量，呵呵 

public class LogFilter extends HttpServlet implements Filter { 
private FilterConfig filterConfig; 

// Handle the passed-in FilterConfig 
public void init(FilterConfig filterConfig) throws ServletException { 
this.filterConfig = filterConfig; 
} 

// Process the request/response pair 
public void doFilter(ServletRequest request, ServletResponse response, 
FilterChain filterChain) { 
try { 

HttpServletRequest httpRequest = (HttpServletRequest) request; 
String uriStr = httpRequest.getServletPath(); 

if (uriStr != null && !uriStr.trim().equals("")) { 

UserInfo user = (UserInfo) httpRequest.getSession() 
.getAttribute(Constant.USERINFO_IN_SESSION); 
String userId = "anonymous", userName = "anonymous"; 
if (user != null) { 
userId = user.getUserid(); 
userName = user.getUserName(); 
} 

DhccPortalLog dpl = new DhccPortalLog(); 
dpl.setUrl(uriStr); 
dpl.setUserid(userId); 
dpl.setUsename(userName); 
java.sql.Date pubTime = new java.sql.Date( new java.util.Date().getTime() ); 
dpl.setAccessdate(pubTime); 
dpl.setIp(httpRequest.getRemoteAddr()); 

DhccPortalLogDAO dplDao = new DhccPortalLogDAO(); 
Transaction tx = dplDao.getSession().beginTransaction(); 
try { 
dplDao.save(dpl); 
tx.commit(); 
} catch (Exception e) { 
tx.rollback(); 

} finally { 
dplDao.getSession().close(); 
} 
} 

} catch (Exception sx) { 
filterConfig.getServletContext().log(sx.getMessage()); 
} finally { 
try { 
filterChain.doFilter(request, response); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
} 
} 

// Clean up resources 
public void destroy() { 
} 
} 

public class LogFilter extends HttpServlet implements Filter { 
private FilterConfig filterConfig; 

// Handle the passed-in FilterConfig 
public void init(FilterConfig filterConfig) throws ServletException { 
this.filterConfig = filterConfig; 
} 

// Process the request/response pair 
public void doFilter(ServletRequest request, ServletResponse response, 
FilterChain filterChain) { 
try { 

HttpServletRequest httpRequest = (HttpServletRequest) request; 
String uriStr = httpRequest.getServletPath(); 

if (uriStr != null && !uriStr.trim().equals("")) { 

UserInfo user = (UserInfo) httpRequest.getSession() 
.getAttribute(Constant.USERINFO_IN_SESSION); 
String userId = "anonymous", userName = "anonymous"; 
if (user != null) { 
userId = user.getUserid(); 
userName = user.getUserName(); 
} 

DhccPortalLog dpl = new DhccPortalLog(); 
dpl.setUrl(uriStr); 
dpl.setUserid(userId); 
dpl.setUsename(userName); 
java.sql.Date pubTime = new java.sql.Date( new java.util.Date().getTime() ); 
dpl.setAccessdate(pubTime); 
dpl.setIp(httpRequest.getRemoteAddr()); 

DhccPortalLogDAO dplDao = new DhccPortalLogDAO(); 
Transaction tx = dplDao.getSession().beginTransaction(); 
try { 
dplDao.save(dpl); 
tx.commit(); 
} catch (Exception e) { 
tx.rollback(); 

} finally { 
dplDao.getSession().close(); 
} 
} 

} catch (Exception sx) { 
filterConfig.getServletContext().log(sx.getMessage()); 
} finally { 
try { 
filterChain.doFilter(request, response); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
} 
} 

// Clean up resources 
public void destroy() { 
} 
}