//過濾器類
public class EcondingFilter implements Filter {
private String charset = null;
private ServletContext context = null;
private String path = "";
/**
* 在銷毀前將數據存入本地文件中
*/
public void destroy() {
//獲取servleContext中的屬性的那個值
String nums = (String) context.getAttribute("nums");
//創建寫入流
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銷毀");
}

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();//獲取每次訪問的action的相對路徑
<img alt="" src="http://img.blog.csdn.net/20130728233435953?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQva2tyZ3diag==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center"><img alt="" src="http://img.blog.csdn.net/20130728233445625?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQva2tyZ3diag==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center"> //判斷路徑，如果是登陸的那個action，就讓保存的context里面的那個屬性加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");

}

public void init(FilterConfig filterConfig) throws ServletException {
// TODO Auto-generated method stub
System.out.println("filter初始化");
//獲取編碼格式
charset = filterConfig.getInitParameter("encoding");
//獲取servletContext
context = filterConfig.getServletContext();
System.out.println(charset);

path = context.getRealPath("");
File file = new File("D://text.txt");
if (!file.exists()) {//判斷文件是否存在
// 如果文件不存在，就創建一個文件，保存在D盤中
file = new File("d://text.txt");
FileWriter fw = null;
BufferedWriter bw = null;
try {
fw = new FileWriter(file);
bw = new BufferedWriter(fw);
bw.write(0 + "");// 寫入初始化數據0
} 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();

}
}
}
//當每次tomcat啟動服務時，進行讀取創建的那個文件
path = "d://text.txt";
// 從本地讀取訪問的人數的文件
FileReader fr = null;
BufferedReader bf = null;
String nums = "";
try {
fr = new FileReader(path);
bf = new BufferedReader(fr);
nums = bf.readLine();
System.out.println(nums);
} catch (Exception e) {
e.printStackTrace();
} finally {

try {
if (bf != null) {
bf.close();
}
if (fr != null) {
fr.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//將獲得到的數據保存在servletContext中
context.setAttribute("nums", nums);
}

}