Parse tomcat logs and insert them into a hashmap. Matches log entries that match a date timestamp regex and concatenates any subsequent detail log entries into a single line until it reaches the next entry starting with a date.

TomcatLogViewService.java

public class LogService {
	private static HashMap<Integer, String> esbLogCache = new HashMap<Integer, String>();
	private static String logDateRegex = "^[a-zA-Z]{3} (\\d)+, (\\d){4} (\\d)+:(\\d){2}:(\\d){2} (AM|PM).*";
	
	static {		
		try {
			BufferedReader br = new BufferedReader(new InputStreamReader(getEsbLog()));
			int row = 0;
			boolean firstRead = true;
			for (String line = br.readLine(); line != null; line = firstRead ? br.readLine() : line) {	
				StringBuilder sb = new StringBuilder();
				firstRead = false;
				if (line.matches(logDateRegex)) {
					sb.append(line.trim()); 
					sb.append(" ");
					int detailLines = 0;
					while ((line = br.readLine()) != null && !line.matches(logDateRegex)) {
						if(detailLines < 10) { //don't include > 10 lines, spreadsheet cells have max cell contents of 32K char
							sb.append(line.trim());
							sb.append(" ");
							detailLines++;
						} else if (detailLines == 10) {
							sb.append("...");
						} 
					}
				}
				esbLogCache.put(row++, sb.toString());
			}
		} catch (FileNotFoundException e) {
			print(e.getMessage());
		} catch (IOException e) {
			print(e.getMessage());
		}	
	}
	
	public static InputStream getEsbLog() throws FileNotFoundException {
		String root = System.getenv("COF_CATALINA_HOME");
		return new FileInputStream(new File(root + File.separator + "logs" + File.separator +"catalina.out"));
	}
	
	/**
	 * With given index range, returns list of selected log entries.    
	 * 
	 * @param start Starting index of log row number to retrieve
	 * @param end Ending index of log row number to retrieve
	 * @return
	 */
	public static List<String> retrieveLogView(int start, int end) {
		List<String> logView = new ArrayList<String>();
		int row = start;
		while(row < end) {
			logView.add(esbLogCache.get(row++));
		}
		return logView;
	}
	
	private static void print(String s) {
		System.out.println(s);
	}
}