jsp实现网页计数器的过程

//过滤器类
public class EcondingFilter implements Filter {
private String charset = null;
private ServletContext context = null;
private String path = "";
/**
* 在销毁前将数据存入本地文件中
*/
public void destroy() {
//获取servleContext中的属性的那个值
String nums = (String) context.getAttribute("nums");
//创建写入流
FileWriter fw = null;
BufferedWriter bw = null;
try {
fw = new FileWriter(path);
bw = new BufferedWriter(fw);
bw.write(nums);
} catch (Exception e) {
e.printStackTrace();
} finally {

try {
if (bw != null) {
bw.close();
}
if (fw != null) {
fw.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
System.out.println("filter销毁");
}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
System.out.println("doFilter前");
String path = ((HttpServletRequest)request).getServletPath();//获取每次访问的action的相对路径
//判断路径，如果是登陆的那个action，就让保存的context里面的那个属性加1
if(path.endsWith("/login.action")){
context.setAttribute("nums",Integer.parseInt(context.getAttribute("nums").toString())+1+"");
}
request.setCharacterEncoding(charset);
response.setCharacterEncoding(charset);
chain.doFilter(request, response);
System.out.println("doFilter后");

}