Parsing Apache access log in Java

Web server log which maintains a history of page requests, typically appended to the end of the file. Information about the request, including client IP address, request date/time, page requested, HTTP code, bytes served, user agent, and referrer are typically added. Given a web server log records, find the total number of successful HTTL responses (200 code) for IP addresses with successful responses. 

Examples:

Input : Sample Access Log
192.168.1.2 - - [17/Sep/2013:22:18:19 -0700] "GET /abc HTTP/1.1" 404 201
192.168.1.2 - - [17/Sep/2013:22:18:19 -0700] "GET /favicon.ico HTTP/1.1" 200 1406
192.168.1.2 - - [17/Sep/2013:22:18:27 -0700] "GET /wp/ HTTP/1.1" 200 5325
192.168.1.2 - - [17/Sep/2013:22:18:27 -0700] "GET /wp/wp-content/themes/twentytwelve/style.css?ver=3.5.1 HTTP/1.1" 200 35292
192.168.1.3 - - [17/Sep/2013:22:18:27 -0700] "GET /wp/wp-content/themes/twentytwelve/js/navigation.js?ver=1.0 HTTP/1.1" 200 863

Output :
192.168.1.3 1
192.168.1.2 3

Prerequisite : Regular Expression in Java

Implementation:

java

// Java program to count the no. of IP address
// count for successful http response 200 code.
import java.io.*;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class FindSuccessIpCount {

    public static void findSuccessIpCount(String record)
    {
        // Creating a regular expression for the records
        final String regex = "^(\\S+) (\\S+) (\\S+) " +
            "\\[([\\w:/]+\\s[+\\-]\\d{4})\\] \"(\\S+)" +
            " (\\S+)\\s*(\\S+)?\\s*\" (\\d{3}) (\\S+)";

        final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
        final Matcher matcher = pattern.matcher(record);

        // Creating a Hashmap containing string as
        // the key and integer as the value.
        HashMap<String, Integer> countIP = new HashMap<String, Integer>();
        while (matcher.find()) {

            String IP = matcher.group(1);
            String Response = matcher.group(8);
            int response = Integer.parseInt(Response);

            // Inserting the IP addresses in the
            // HashMap and maintaining the frequency
            // for each HTTP 200 code.
            if (response == 200) {
                if (countIP.containsKey(IP)) {
                    countIP.put(IP, countIP.get(IP) + 1);
                }
                else {
                    countIP.put(IP, 1);
                }
            }
        }

        // Printing the hashmap
        for (Map.Entry entry : countIP.entrySet()) {
            System.out.println(entry.getKey() + " " + entry.getValue());
        }
    }
    public static void main(String[] args)
    {
        final String log = "123.123.123.123 - - [26/Apr/2000:00:23:48 -0400] \"GET /pics/wpaper.gif HTTP/1.0\" 200 6248 \"http:// www.jafsoft.com/asctortf/\" \"Mozilla/4.05 (Macintosh; I; PPC)\"\n"
                        + "123.123.123.123 - - [26/Apr/2000:00:23:47 -0400] \"GET /asctortf/ HTTP/1.0\" 200 8130 \"http:// search.netscape.com/Computers/Data_Formats/Document/Text/RTF\" \"Mozilla/4.05 (Macintosh; I; PPC)\"\n"
                        + "123.123.123.124 - - [26/Apr/2000:00:23:48 -0400] \"GET /pics/5star2000.gif HTTP/1.0\" 200 4005 \"http:// www.jafsoft.com/asctortf/\" \"Mozilla/4.05 (Macintosh; I; PPC)\"\n"
                        + "123.123.123.123 - - [26/Apr/2000:00:23:50 -0400] \"GET /pics/5star.gif HTTP/1.0\" 404 1031 \"http:// www.jafsoft.com/asctortf/\" \"Mozilla/4.05 (Macintosh; I; PPC)\"\n"
                        + "123.123.123.126 - - [26/Apr/2000:00:23:51 -0400] \"GET /pics/a2hlogo.jpg HTTP/1.0\" 200 4282 \"http:// www.jafsoft.com/asctortf/\" \"Mozilla/4.05 (Macintosh; I; PPC)\"\n"
                        + "123.123.123.123 - - [26/Apr/2000:00:23:51 -0400] \"GET /cgi-bin/newcount?jafsof3&width=4&font=digital&noshow HTTP/1.0\" 200 36 \"http:// www.jafsoft.com/asctortf/\" \"Mozilla/4.05 (Macintosh; I; PPC)\"\n";

        findSuccessIpCount(log);
    }
}

Output

123.123.123.126 1
123.123.123.124 1
123.123.123.123 3