<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log" suffix=".txt"
               pattern="%h %l %u %t &quot;%r&quot; %s %b" />

* %a - Remote IP address // 这是记录访问者的IP，在日志里是127.0.0.1
* %A - Local IP address // 这是记录本地服务器的IP，在日志里是192.168.254.108
* %b - Bytes sent, excluding HTTP headers, or '-' if zero // 发送信息的字节数，不包括http头，如果字节数为0的话，显示为-
* %B - Bytes sent, excluding HTTP headers // 发送信息的字节数，不包括http头。
* %h - Remote host name (or IP address if resolveHosts is false) //服务器的名称。如果resolveHosts为false的话，这里就是IP地址了，例如我的日志里是10.217.14.16
* %H - Request protocol //访问者的协议，这里是HTTP/1.0
* %l - Remote logical username from identd (always returns '-') // 官方解释：Remote logical username from identd (可能这样翻译：记录浏览者进行身份验证时提供的名字)(always returns '-')
* %m - Request method (GET, POST, etc.) // 访问的方式，是GET还是POST
* %p - Local port on which this request was received // 本地接收访问的端口
* %q - Query string (prepended with a '?' if it exists) // 比如你访问的是aaa.jsp?bbb=ccc，那么这里就显示?bbb=ccc，就是querystring的意思
* %r - First line of the request (method and request URI) // First line of the request (method and request URI) 请求的方法和URL
* %s - HTTP status code of the response // http的响应状态码
* %S - User session ID // 用户的session ID,这个session ID大家可以另外查一下详细的解释，反正每次都会生成不同的session ID
* %t - Date and time, in Common Log Format // 请求时间
* %u - Remote user that was authenticated (if any), else '-' // 得到了验证的访问者，否则就是"-"
* %U - Requested URL path // 访问的URL地址，我这里是/rightmainima/leftbott4.swf
* %v - Local server name // 服务器名称，可能就是你url里面写的那个吧，我这里是localhost
* %D - Time taken to process the request, in millis // 请求消耗的时间，以毫秒记
* %T - Time taken to process the request, in seconds //请求消耗的时间，以秒记
There is also support to write information from the cookie, incoming header, the Session or something else in the ServletRequest.
It is modeled after the apache syntax:
* %{xxx}i for incoming headers
* %{xxx}c for a specific cookie
* %{xxx}r xxx is an attribute in the ServletRequest
* %{xxx}s xxx is an attribute in the HttpSession

140.205.201.39 - - [31/Aug/2017:17:06:52 +0800] "GET /clusters.jsf HTTP/1.1" 404 -
60.191.38.77 - - [31/Aug/2017:17:11:35 +0800] "GET / HTTP/1.1" 404 -
61.232.253.54 - - [31/Aug/2017:19:04:53 +0800] "GET / HTTP/1.1" 404 -
100.116.151.190 - - [31/Aug/2017:20:45:17 +0800] "GET /CloudPayment/bill/querySelfPayList.do HTTP/1.0" 200 60
100.116.41.2 - - [31/Aug/2017:20:45:34 +0800] "GET /CloudPayment/user/pay.do HTTP/1.0" 200 1422
100.116.151.145 - - [31/Aug/2017:20:46:22 +0800] "GET /CloudPayment/user/pay.do HTTP/1.0" 200 1422
100.116.41.41 - - [31/Aug/2017:20:46:42 +0800] "GET /CloudPayment/user/pay.do HTTP/1.0" 200 1422
100.116.151.181 - - [31/Aug/2017:20:47:21 +0800] "GET /CloudPayment/user/pay.do HTTP/1.0" 200 1422
100.116.151.181 - - [31/Aug/2017:20:47:22 +0800] "GET /CloudPayment/user/pay.do HTTP/1.0" 200 1422

package com.xiaoxiliu
import java.io.IOException;
import java.util.Enumeration;
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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public final class PostDataDumperFilter implements Filter {
  Logger logger = LoggerFactory.getLogger(getClass());
  private FilterConfig filterConfig = null;
  public void destroy() {
    this.filterConfig = null;
  }
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
      throws IOException, ServletException {
    if (filterConfig == null)
      return;
    Enumeration<String> names = request.getParameterNames();
    StringBuilder output = new StringBuilder();
    while (names.hasMoreElements()) {
      String name = (String) names.nextElement();
      output.append(name).append("=");
      String values[] = request.getParameterValues(name);
      for (int i = 0; i < values.length; i++) {
        if (i > 0) {
          output.append("' ");
        }
        output.append(values[i]);
      }
      if (names.hasMoreElements())
        output.append("&");
    }
    request.setAttribute("postdata", output);
    logger.debug("postdata: " + output);
    chain.doFilter(request, response);
  }
  public void init(FilterConfig filterConfig) throws ServletException {
    this.filterConfig = filterConfig;
  }
}