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   /*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  package org.apache.catalina.valves;
  
  
  import static org.jboss.web.CatalinaMessages.MESSAGES;
  
  import java.io.File;
  import java.util.Date;
  import java.util.List;
  
  

Implementation of the Valve interface that generates a web server access log with the detailed line contents matching a configurable pattern. The syntax of the available patterns is similar to that supported by the Apache mod_log_config module. As an additional feature, automatic rollover of log files when the date changes is also supported.

Patterns for the logged message may include constant text or any of the following replacement strings, for which the corresponding information from the specified Response is substituted:

  • %a - Remote IP address
  • %A - Local IP address
  • %b - Bytes sent, excluding HTTP headers, or '-' if no bytes were sent
  • %B - Bytes sent, excluding HTTP headers
  • %h - Remote host name
  • %H - Request protocol
  • %l - Remote logical username from identd (always returns '-')
  • %m - Request method
  • %p - Local port
  • %q - Query string (prepended with a '?' if it exists, otherwise an empty string
  • %r - First line of the request
  • %s - HTTP status code of the response
  • %S - User session ID
  • %t - Date and time, in Common Log Format format
  • %u - Remote user that was authenticated
  • %U - Requested URL path
  • %v - Local server name
  • %D - Time taken to process the request, in millis
  • %T - Time taken to process the request, in seconds
  • %I - current Request thread name (can compare later with stacktraces)

In addition, the caller can specify one of the following aliases for commonly utilized patterns:

  • common - %h %l %u %t "%r" %s %b
  • combined - %h %l %u %t "%r" %s %b "%{Referer}i" "%{User-Agent}i"

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}o for outgoing response 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

Conditional logging is also supported. This can be done with the condition property. If the value returned from ServletRequest.getAttribute(condition) yields a non-null value. The logging will be skipped.

Author(s):
Craig R. McClanahan
Jason Brittain
Remy Maucherat
Takayuki Kaneko
Peter Rossbach
Version:
$Revision: 1237 $ $Date: 2009-11-03 02:55:48 +0100 (Tue, 03 Nov 2009) $
 
 
 public class AccessLogValve
     extends ValveBase
     implements Lifecycle {
 
     // ----------------------------------------------------- Instance Variables
 

    
The as-of date for the currently open log file, or a zero-length string if there is no open log file.
 
     private String dateStamp = "";


    
The directory in which log files are created.
 
     private String directory = "logs";


    
The descriptive information about this implementation.
 
     protected static final String info =
         "org.apache.catalina.valves.AccessLogValve/2.1";


    
The lifecycle event support for this component.
 
     protected LifecycleSupport lifecycle = new LifecycleSupport(this);


    
The set of month abbreviations for log messages.
 
     protected static final String months[] =
     { "Jan""Feb""Mar""Apr""May""Jun",
       "Jul""Aug""Sep""Oct""Nov""Dec" };


    
enabled this component
 
     protected boolean enabled = true;

    
The pattern used to format our access log lines.
 
     protected String pattern = null;


    
The prefix that is added to log file filenames.
 
     protected String prefix = "access_log.";


    
Should we rotate our log file? Default is true (like old behavior)
 
     protected boolean rotatable = true;


    
Buffered logging.
 
     private boolean buffered = true;


    
Has this component been started yet?
 
     protected boolean started = false;


    
The suffix that is added to log file filenames.
 
     protected String suffix = "";


    
The PrintWriter to which we are currently logging, if any.
 
     protected PrintWriter writer = null;


    
A date formatter to format a Date into a date in the format "yyyy-MM-dd".
 
     protected SimpleDateFormat fileDateFormatter = null;


    
A date formatter to format Dates into a day string in the format "dd".
 
     private SimpleDateFormat dayFormatter = null;


    
A date formatter to format a Date into a month string in the format "MM".
 
     private SimpleDateFormat monthFormatter = null;


    
A date formatter to format a Date into a year string in the format "yyyy".
 
     private SimpleDateFormat yearFormatter = null;


    
A date formatter to format a Date into a time in the format "kk:mm:ss" (kk is a 24-hour representation of the hour).
 
     private SimpleDateFormat timeFormatter = null;


    
The system timezone.
 
     private TimeZone timezone = null;

    
    
The time zone offset relative to GMT in text form when daylight saving is not in operation.
 
     private String timeZoneNoDST = null;


    
The time zone offset relative to GMT in text form when daylight saving is in operation.
 
     private String timeZoneDST = null;
    
    
    
The current log file we are writing to. Helpful when checkExists is true.
 
     protected File currentLogFile = null;
    
    
The system time when we last updated the Date that this valve uses for log lines.
 
     private Date currentDate = null;
     
     private long currentMillis = 0;


    
Resolve hosts.
 
     private boolean resolveHosts = false;


    
Instant when the log daily rotation was last checked.
 
     private long rotationLastChecked = 0L;

    
Do we check for log file existence? Helpful if an external agent renames the log file so we can automagically recreate it.
 
     private boolean checkExists = false;
    
    
    
Are we doing conditional logging. default false.
 
     protected String condition = null;


    
Date format to place in log file name. Use at your own risk!
 
     protected String fileDateFormat = null;
    
    
Array of AccessLogElement, they will be used to make log message.
 
     protected AccessLogElement[] logElements = null;
 
     // ------------------------------------------------------------- Properties
 
    

Returns:
Returns the enabled.
 
     public boolean getEnabled() {
         return ;
     }

    

Parameters:
enabled The enabled to set.
 
     public void setEnabled(boolean enabled) {
         this. = enabled;
     }

    
Return the directory in which we create log files.
 
     public String getDirectory() {
         return ();
     }


    
Set the directory in which we create log files.

Parameters:
directory The new log file directory
 
     public void setDirectory(String directory) {
         this. = directory;
     }


    
Return descriptive information about this implementation.
 
     public String getInfo() {
         return ();
     }


    
Return the format pattern.
 
     public String getPattern() {
         return (this.);
     }


    
Set the format pattern, first translating any recognized alias.

Parameters:
pattern The new pattern
 
     public void setPattern(String pattern) {
         if (pattern == null)
             pattern = "";
         if (pattern.equals(..))
             pattern = ..;
         if (pattern.equals(..))
             pattern = ..;
         this. = pattern;
          = createLogElements();
     }


    
Check for file existence before logging.
 
     public boolean isCheckExists() {
 
         return ;
 
     }


    
Set whether to check for log file existence before logging.

Parameters:
checkExists true meaning to check for file existence.
 
     public void setCheckExists(boolean checkExists) {
 
         this. = checkExists;
 
     }
    
    
    
Return the log file prefix.
 
     public String getPrefix() {
         return ();
     }


    
Set the log file prefix.

Parameters:
prefix The new log file prefix
 
     public void setPrefix(String prefix) {
         this. = prefix;
     }


    
Should we rotate the logs
 
     public boolean isRotatable() {
         return ;
     }


    
Set the value is we should we rotate the logs

Parameters:
rotatable true is we should rotate.
 
     public void setRotatable(boolean rotatable) {
         this. = rotatable;
     }


    
Is the logging buffered
 
     public boolean isBuffered() {
         return ;
     }


    
Set the value if the logging should be buffered

Parameters:
buffered true if buffered.
 
     public void setBuffered(boolean buffered) {
         this. = buffered;
     }


    
Return the log file suffix.
 
     public String getSuffix() {
         return ();
     }


    
Set the log file suffix.

Parameters:
suffix The new log file suffix
 
     public void setSuffix(String suffix) {
         this. = suffix;
     }


    
Set the resolve hosts flag.

Parameters:
resolveHosts The new resolve hosts value
 
     public void setResolveHosts(boolean resolveHosts) {
         this. = resolveHosts;
     }


    
Get the value of the resolve hosts flag.
 
     public boolean isResolveHosts() {
         return ;
     }


    
Return whether the attribute name to look for when performing conditional loggging. If null, every request is logged.
 
     public String getCondition() {
         return ;
     }


    
Set the ServletRequest.attribute to look for to perform conditional logging. Set to null to log everything.

Parameters:
condition Set to null to log everything
 
     public void setCondition(String condition) {
         this. = condition;
     }

    
Return the date format date based log rotation.
 
     public String getFileDateFormat() {
         return ;
     }


    
Set the date format date based log rotation.
 
     public void setFileDateFormat(String fileDateFormat) {
         this. =  fileDateFormat;
     }
 
     // --------------------------------------------------------- Public Methods
 
    
Execute a periodic task, such as reloading, etc. This method will be invoked inside the classloading context of this container. Unexpected throwables will be caught and logged.
 
     public void backgroundProcess() {
         if ( && getEnabled() &&  != null && ) {
             .flush();
         }
     }    

    
Log a message summarizing the specified request and response, according to the format specified by the pattern property.

Parameters:
request Request being processed
response Response being processed
Throws:
java.io.IOException if an input/output error has occurred
javax.servlet.ServletException if a servlet error has occurred
 
     public void invoke(Request requestResponse responsethrows IOException,
             ServletException {
 
         if ( && getEnabled()) {                
             // Pass this request on to the next valve in our pipeline
             long t1 = System.currentTimeMillis();
     
             getNext().invoke(requestresponse);
     
             long t2 = System.currentTimeMillis();
             long time = t2 - t1;
     
             if ( == null ||  != null
                     && null != request.getRequest().getAttribute()) {
                 return;
             }
     
             Date date = getDate();
             StringBuilder result = new StringBuilder();
     
             for (int i = 0; i < .i++) {
                 [i].addElement(resultdaterequestresponsetime);
             }
     
             log(result.toString());
         } else
             getNext().invoke(requestresponse);       
     }

    
    
Rename the existing log file to something else. Then open the old log file name up once again. Intended to be called by a JMX agent.

Parameters:
newFileName The file name to move the log file entry to
Returns:
true if a file was rotated with no error
 
     public synchronized boolean rotate(String newFileName) {
 
         if ( != null) {
             File holder = ;
             close();
             try {
                 holder.renameTo(new File(newFileName));
             } catch (Throwable e) {
                 ..errorRotatingAccessLog(e);
             }
 
             /* Make sure date is correct */
              = new Date(System.currentTimeMillis());
              = .format();
 
             open();
             return true;
         } else {
             return false;
         }
 
     }
 
     // -------------------------------------------------------- Private Methods
 

    
Close the currently open log file (if any)
 
     private synchronized void close() {
         if ( == null) {
             return;
         }
         .flush();
         .close();
          = null;
          = "";
          = null;
     }


    
Log the specified message to the log file, switching files if the date has changed since the previous log call.

Parameters:
message Message to be logged
 
     public void log(String message) {
         if () {
             // Only do a logfile switch check once a second, max.
             long systime = System.currentTimeMillis();
             if ((systime - ) > 1000) {
 
                 // We need a new currentDate
                  = new Date(systime);
                  = systime;
 
                 // Check for a change of date
                 String tsDate = .format();
 
                 // If the date has changed, switch log files
                 if (!.equals(tsDate)) {
                     synchronized (this) {
                         if (!.equals(tsDate)) {
                             close();
                              = tsDate;
                             open();
                         }
                     }
                 }
             }
         }
         
         /* In case something external rotated the file instead */
         if () {
             synchronized (this) {
                 if ( != null && !.exists()) {
                     try {
                         close();
                     } catch (Throwable e) {
                         ..errorClosingOldAccessLog(e);
                     }
 
                     /* Make sure date is correct */
                      = new Date(System.currentTimeMillis());
                      = .format();
 
                     open();
                 }
             }
         }
 
         // Log this message
         if ( != null) {
             .println(message);
             if (!) {
                 .flush();
             }
         }
 
     }


    
Return the month abbreviation for the specified month, which must be a two-digit String.

Parameters:
month Month number ("01" .. "12").
 
     private String lookup(String month) {
         int index;
         try {
             index = Integer.parseInt(month) - 1;
         } catch (Throwable t) {
             index = 0;  // Can not happen, in theory
         }
         return ([index]);
     }


    
Open the new log file for the date specified by dateStamp.
 
     protected synchronized void open() {
         // Create the directory if necessary
         File dir = new File();
         if (!dir.isAbsolute())
             dir = new File(System.getProperty("catalina.base"), );
         dir.mkdirs();
 
         // Open the current log file
         try {
             String pathname;
             // If no rotate - no need for dateStamp in fileName
             if () {
                 pathname = dir.getAbsolutePath() + . + 
                         +  + ;
             } else {
                 pathname = dir.getAbsolutePath() + . + 
                         + ;
             }
              = new PrintWriter(new BufferedWriter(new FileWriter(
                     pathnametrue), 128000), false);
             
              = new File(pathname);
         } catch (IOException e) {
              = null;
              = null;
         }
     }
 
    
This method returns a Date object that is accurate to within one second. If a thread calls this method to get a Date and it's been less than 1 second since a new Date was created, this method simply gives out the same Date again so that the system doesn't spend time creating Date objects unnecessarily.

Returns:
Date
 
     private Date getDate() {
         // Only create a new Date once per second, max.
         long systime = System.currentTimeMillis();
         if ((systime - ) > 1000) {
             synchronized (this) {
                 if ((systime - ) > 1000) {
                      = new Date(systime);
                      = systime;
                 }
             }
         }
         return ;
     }
 
 
     private String getTimeZone(Date date) {
         if (.inDaylightTime(date)) {
             return ;
         } else {
             return ;
         }
     }
     
     
     private String calculateTimeZoneOffset(long offset) {
         StringBuilder tz = new StringBuilder();
         if ((offset < 0)) {
             tz.append("-");
             offset = -offset;
         } else {
             tz.append("+");
         }
 
         long hourOffset = offset / (1000 * 60 * 60);
         long minuteOffset = (offset / (1000 * 60)) % 60;
 
         if (hourOffset < 10)
             tz.append("0");
         tz.append(hourOffset);
 
         if (minuteOffset < 10)
             tz.append("0");
         tz.append(minuteOffset);
 
         return tz.toString();
     }
 
 
     // ------------------------------------------------------ Lifecycle Methods
 

    
Add a lifecycle event listener to this component.

Parameters:
listener The listener to add
 
     public void addLifecycleListener(LifecycleListener listener) {
         .addLifecycleListener(listener);
     }


    
Get the lifecycle listeners associated with this lifecycle. If this Lifecycle has no listeners registered, a zero-length array is returned.
 
         return .findLifecycleListeners();
     }


    
Remove a lifecycle event listener from this component.

Parameters:
listener The listener to add
 
     public void removeLifecycleListener(LifecycleListener listener) {
         .removeLifecycleListener(listener);
     }


    
Prepare for the beginning of active use of the public methods of this component. This method should be called after configure(), and before any of the public methods of the component are utilized.

Throws:
org.apache.catalina.LifecycleException if this component detects a fatal error that prevents this component from being used
 
     public void start() throws LifecycleException {
 
         // Validate and update our current component state
         if ()
             throw new LifecycleException(.valveAlreadyStarted());
         .fireLifecycleEvent(null);
          = true;
 
         // Initialize the timeZone, Date formatters, and currentDate
          = TimeZone.getDefault();
         int offset = .getDSTSavings();
          = calculateTimeZoneOffset(.getRawOffset() + offset);
 
         if ( == null || .length() == 0)
              = "yyyy-MM-dd";
          = new SimpleDateFormat("dd");
          = new SimpleDateFormat("MM");
          = new SimpleDateFormat("yyyy");
          = new SimpleDateFormat("HH:mm:ss");
          = new Date();
         open();
     }


    
Gracefully terminate the active use of the public methods of this component. This method should be the last one called on a given instance of this component.

Throws:
org.apache.catalina.LifecycleException if this component detects a fatal error that needs to be reported
 
     public void stop() throws LifecycleException {
 
         // Validate and update our current component state
         if (!)
             throw new LifecycleException(.valveNotStarted());
         .fireLifecycleEvent(null);
          = false;
         
         close();
     }
    
    
AccessLogElement writes the partial message into the buffer.
 
     protected interface AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time);
 
     }
    
    
write thread name - %I
 
     protected class ThreadNameElement implements AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             RequestInfo info = request.getCoyoteRequest().getRequestProcessor();
             if(info != null) {
                 buf.append(info.getWorkerThreadName());
             } else {
                 buf.append("-");
             }
         }
     }
    
    
write local IP address - %A
 
     protected class LocalAddrElement implements AccessLogElement {
         
         private String value = null;
         
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             if ( == null) {
                 synchronized (this) {
                     try {
                          = InetAddress.getLocalHost().getHostAddress();
                     } catch (Throwable e) {
                          = "127.0.0.1";
                     }
                 }
             }
             buf.append();
         }
     }
    
    
write remote IP address - %a
 
     protected class RemoteAddrElement implements AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             buf.append(request.getRemoteAddr());
         }
     }
    
    
write remote host name - %h
 
     protected class HostElement implements AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             if () {
                 buf.append(request.getRemoteHost());
             } else {
                 buf.append(request.getRemoteAddr());
             }
         }
     }
    
    
write remote logical username from identd (always returns '-') - %l
 
     protected class LogicalUserNameElement implements AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             buf.append('-');
         }
     }
    
    
write request protocol - %H
 
     protected class ProtocolElement implements AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             buf.append(request.getProtocol());
         }
     }

    
write remote user that was authenticated (if any), else '-' - %u
 
     protected class UserElement implements AccessLogElement {
         public void addElement(StringBuilder bufDate dateRequest request,
                 Response responselong time) {
             if (request != null) {
                 String value = request.getRemoteUser();
                 if (value != null) {
                     buf.append(value);
                 } else {
                     buf.append('-');
                 }
             } else {
                 buf.append('-');
             }
         }
     }

    
write date and time, in Common Log Format - %t
    protected class DateAndTimeElement implements AccessLogElement {
        private Date currentDate = new Date(0);
        private String currentDateString = null;
        
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if ( != date) {
                synchronized (this) {
                    if ( != date) {
                        StringBuilder current = new StringBuilder(32);
                        current.append('[');
                        current.append(.format(date)); // Day
                        current.append('/');
                        current.append(lookup(.format(date))); // Month
                        current.append('/');
                        current.append(.format(date)); // Year
                        current.append(':');
                        current.append(.format(date)); // Time
                        current.append(' ');
                        current.append(getTimeZone(date)); // Timezone
                        current.append(']');
                         = current.toString();
                         = date;
                    }
                }
            }
            buf.append();
        }
    }

    
write first line of the request (method and request URI) - %r
    protected class RequestElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if (request != null) {
                buf.append(request.getMethod());
                buf.append(' ');
                buf.append(request.getRequestURI());
                if (request.getQueryString() != null) {
                    buf.append('?');
                    buf.append(request.getQueryString());
                }
                buf.append(' ');
                buf.append(request.getProtocol());
            } else {
                buf.append("- - ");
            }
        }
    }

    
write HTTP status code of the response - %s
    protected class HttpStatusCodeElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if (response != null) {
                buf.append(response.getStatus());
            } else {
                buf.append('-');
            }
        }
    }

    
write local port on which this request was received - %p
    protected class LocalPortElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            buf.append(request.getServerPort());
        }
    }

    
write bytes sent, excluding HTTP headers - %b, %B
    protected class ByteSentElement implements AccessLogElement {
        private boolean conversion;

        
if conversion is true, write '-' instead of 0 - %b
        public ByteSentElement(boolean conversion) {
            this. = conversion;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            long length = response.getContentCountLong() ;
            if (length <= 0 && ) {
                buf.append('-');
            } else {
                buf.append(length);
            }
        }
    }

    
write request method (GET, POST, etc.) - %m
    protected class MethodElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if (request != null) {
                buf.append(request.getMethod());
            }
        }
    }

    
write time taken to process the request - %D, %T
    protected class ElapsedTimeElement implements AccessLogElement {
        private boolean millis;

        
if millis is true, write time in millis - %D if millis is false, write time in seconds - %T
        public ElapsedTimeElement(boolean millis) {
            this. = millis;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if () {
                buf.append(time);
            } else {
                // second
                buf.append(time / 1000);
                buf.append('.');
                int remains = (int) (time % 1000);
                buf.append(remains / 100);
                remains = remains % 100;
                buf.append(remains / 10);
                buf.append(remains % 10);
            }
        }
    }
    
    
write Query string (prepended with a '?' if it exists) - %q
    protected class QueryElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            String query = null;
            if (request != null)
                query = request.getQueryString();
            if (query != null) {
                buf.append('?');
                buf.append(query);
            }
        }
    }

    
write user session ID - %S
    protected class SessionIdElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if (request != null) {
                if (request.getSession(false) != null) {
                    buf.append(request.getSessionInternal(false)
                            .getIdInternal());
                } else {
                    buf.append('-');
                }
            } else {
                buf.append('-');
            }
        }
    }

    
write requested URL path - %U
    protected class RequestURIElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            if (request != null) {
                buf.append(request.getRequestURI());
            } else {
                buf.append('-');
            }
        }
    }

    
write local server name - %v
    protected class LocalServerNameElement implements AccessLogElement {
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            buf.append(request.getServerName());
        }
    }
    
    
write any string
    protected class StringElement implements AccessLogElement {
        private String str;
        public StringElement(String str) {
            this. = str;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            buf.append();
        }
    }

    
write incoming headers - %{xxx}i
    protected class HeaderElement implements AccessLogElement {
        private String header;
        public HeaderElement(String header) {
            this. = header;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            String value = request.getHeader();
            if (value == null) {
                buf.append('-');
            } else {
                buf.append(value);
            }
        }
    }

    
write a specific cookie - %{xxx}c
    protected class CookieElement implements AccessLogElement {
        private String header;
        public CookieElement(String header) {
            this. = header;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            String value = "-";
            Cookie[] c = request.getCookies();
            if (c != null) {
                for (int i = 0; i < c.lengthi++) {
                    if (.equals(c[i].getName())) {
                        value = c[i].getValue();
                        break;
                    }
                }
            }
            buf.append(value);
        }
    }

    
write a specific response header - %{xxx}o
    protected class ResponseHeaderElement implements AccessLogElement {
        private String header;
        public ResponseHeaderElement(String header) {
            this. = header;
        }
        
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
           if (null != response) {
                String[] values = response.getHeaderValues();
                if(values.length > 0) {
                    for (int i = 0; i < values.lengthi++) {
                        String string = values[i];
                        buf.append(string) ;
                        if(i+1<values.length)
                            buf.append(",");
                    }
                    return ;
                }
            }
            buf.append("-");
        }
    }
    
    
write an attribute in the ServletRequest - %{xxx}r
    protected class RequestAttributeElement implements AccessLogElement {
        private String header;
        public RequestAttributeElement(String header) {
            this. = header;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            Object value = null;
            if (request != null) {
                value = request.getAttribute();
            } else {
                value = "??";
            }
            if (value != null) {
                if (value instanceof String) {
                    buf.append((Stringvalue);
                } else {
                    buf.append(value.toString());
                }
            } else {
                buf.append('-');
            }
        }
    }

    
write an attribute in the HttpSession - %{xxx}s
    protected class SessionAttributeElement implements AccessLogElement {
        private String header;
        public SessionAttributeElement(String header) {
            this. = header;
        }
        public void addElement(StringBuilder bufDate dateRequest request,
                Response responselong time) {
            Object value = null;
            if (null != request) {
                HttpSession sess = request.getSession(false);
                if (null != sess)
                    value = sess.getAttribute();
            } else {
                value = "??";
            }
            if (value != null) {
                if (value instanceof String) {
                    buf.append((Stringvalue);
                } else {
                    buf.append(value.toString());
                }
            } else {
                buf.append('-');
            }
        }
    }




    
parse pattern string and create the array of AccessLogElement
    protected AccessLogElement[] createLogElements() {
        List<AccessLogElementlist = new ArrayList<AccessLogElement>();
        boolean replace = false;
        StringBuilder buf = new StringBuilder();
        for (int i = 0; i < .length(); i++) {
            char ch = .charAt(i);
            if (replace) {
                /*
                 * For code that processes {, the behavior will be ... if I do
                 * not enounter a closing } - then I ignore the {
                 */
                if ('{' == ch) {
                    StringBuilder name = new StringBuilder();
                    int j = i + 1;
                    for (; j < .length() && '}' != .charAt(j); j++) {
                        name.append(.charAt(j));
                    }
                    if (j + 1 < .length()) {
                        /* the +1 was to account for } which we increment now */
                        j++;
                        list.add(createAccessLogElement(name.toString(),
                                .charAt(j)));
                        i = j/* Since we walked more than one character */
                    } else {
                        // D'oh - end of string - pretend we never did this
                        // and do processing the "old way"
                        list.add(createAccessLogElement(ch));
                    }
                } else {
                    list.add(createAccessLogElement(ch));
                }
                replace = false;
            } else if (ch == '%') {
                replace = true;
                list.add(new StringElement(buf.toString()));
                buf = new StringBuilder();
            } else {
                buf.append(ch);
            }
        }
        if (buf.length() > 0) {
            list.add(new StringElement(buf.toString()));
        }
        return (AccessLogElement[]) list.toArray(new AccessLogElement[0]);
    }

    
create an AccessLogElement implementation which needs header string
    private AccessLogElement createAccessLogElement(String headerchar pattern) {
        switch (pattern) {
        case 'i':
            return new HeaderElement(header);
        case 'c':
            return new CookieElement(header);
        case 'o':
            return new ResponseHeaderElement(header);
        case 'r':
            return new RequestAttributeElement(header);
        case 's':
            return new SessionAttributeElement(header);            
        default:
            return new StringElement("???");
        }
    }

    
create an AccessLogElement implementation
    private AccessLogElement createAccessLogElement(char pattern) {
        switch (pattern) {
        case 'a':
            return new RemoteAddrElement();
        case 'A':
            return new LocalAddrElement();
        case 'b':
            return new ByteSentElement(true);
        case 'B':
            return new ByteSentElement(false);
        case 'D':
            return new ElapsedTimeElement(true);
        case 'h':
            return new HostElement();
        case 'H':
            return new ProtocolElement();
        case 'l':
            return new LogicalUserNameElement();
        case 'm':
            return new MethodElement();
        case 'p':
            return new LocalPortElement();
        case 'q':