In this example we shall show you how to log a method call. We have implemented the LogMethodCall Class, with a simple method to log its messages. The basic steps of the example are described below:
- The
call(String arg1, Object arg2)method of the class takes a String argument and an Object argument and returns a boolean value. - The method creates a FileHandler to write logs to a specific file.
- It creates a new Logger instance and adds the handler to the logger, with
addHandler(Handler handler)API method. - It also adds a logging Level to the logger with
setLevel(Level newLevel)API method. - The method invokes the
entering(String sourceClass, String sourceMethod, Object[] params)API method of the logger, to log an entry to this method. It also invokes theexiting(String sourceClass, String sourceMethod, Object result)API method to log returning from the method. They both take as parameters the class and the method names, so whenever the method is invoked by another method or class, the FileHandler will write to the log file, its invocation entries and return values,
as described in the code snippet below.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | package com.javacodegeeks.snippets.core;import java.util.logging.FileHandler;import java.util.logging.Level;import java.util.logging.Logger;public class LogMethodCall { public static void main(String[] args) throws Exception { LogMethodCall call = new LogMethodCall(); call.method("arg1", new String("arg2")); } public boolean method(String arg1, Object arg2) throws Exception { boolean append = false; FileHandler handler = new FileHandler("default.log", append); Logger logger = Logger.getLogger("com.javacodegeeks.snippets.core"); logger.setLevel(Level.FINEST); logger.addHandler(handler); logger.entering(this.getClass().getName(), "method", new Object[]{arg1, arg2}); boolean result = true; logger.exiting(this.getClass().getName(), "method", new Boolean(result)); return result; }} |
default.log
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | <?xml version="1.0" encoding="windows-1252" standalone="no"?><!DOCTYPE log SYSTEM "logger.dtd"><log><record> <date>2011-11-19T15:50:10</date> <millis>1321710610361</millis> <sequence>0</sequence> <logger>com.javacodegeeks.snippets.core</logger> <level>FINER</level> <class>com.javacodegeeks.snippets.core.LogMethodCall</class> <method>method</method> <thread>10</thread> <message>ENTRY arg1 arg2</message></record><record> <date>2011-11-19T15:50:10</date> <millis>1321710610364</millis> <sequence>1</sequence> <logger>com.javacodegeeks.snippets.core</logger> <level>FINER</level> <class>com.javacodegeeks.snippets.core.LogMethodCall</class> <method>method</method> <thread>10</thread> <message>RETURN true</message></record></log> |
This was an example of how to log a method call in Java.
