Decorator Pattern in Java

Simple Note

(From wiki):

The decorator pattern (also known as Wrapper, an alternative naming shared with the Adapter pattern) is a design pattern that allows behavior to be added to an individual object, either statically or dynamically, without affecting the behavior of other objects from the same class.

Program

https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/DesignPattern/src/decorator

Run TestMain.java to test.

OldSiren().alarm() will only output a message in console, BeepDecorator can wrap OldSiren to add a beep.

Reference:

Decorator pattern

Grate answer at stackoverflow

Builder Pattern in Java

Simple Note

(From wiki):

the intention of the builder pattern is to find a solution to the telescoping constructor anti-pattern. The telescoping constructor anti-pattern occurs when the increase of object constructor parameter combination leads to an exponential list of constructors. Instead of using numerous constructors, the builder pattern uses another object, a builder, that receives each initialization parameter step by step and then returns the resulting constructed object at once.

Program

https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/DesignPattern/src/builder

Run TestMain.java to test.

Add base rice and lots of ingredients one by one to DonburiBuilder then build Donburi.

Reference:

Builder pattern

Grate answer at stackoverflow

Donburi

Factory Method Pattern in Java

Simple Note

(From wiki):

The essence of this pattern is to "Define an interface for creating an object, but let the classes that implement the interface decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses."

Program

https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/DesignPattern/src/factory/factorymethod

Run TestMain.java to test.

abstract class Audience has a method enjoy, will get a Player to play something then enjoy.
the abstract method getPlayer can be overridden by subclass to provide different Player as needed.

Reference:

Factory method pattern (wiki)

Abstract Factory Pattern in Java

Simple Note

(From wiki):

The abstract factory pattern provides a way to encapsulate a group of individual factories that have a common theme without specifying their concrete classes.

(From OODesign)

Offers the interface for creating a family of related object, without explicitly specifying their classes.

Program

https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/DesignPattern/src/factory/abstractfactory

Run TestMain.java to test.

A FoodStore  that sells Bread from BreadFactory in odd weeks and sells PASTA from PastaFactory in even weeks.

In my opinion, Abstract Factory Pattern is most likely 'Chained Simple Factory Pattern'.

Reference:

Abstract factory pattern

Abstract Factory

Simple Factory Pattern in Java

Simple Note

Simple Factory Pattern:
A method that can return different hardcoded subtypes.

Program

https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/DesignPattern/src/factory/simplefactory

BreadFactory that produce WonderfulBread at 3rd day of a week and produce CommonBread in other days

Can rely on the abstract class "Bread" in program, do not need to know whether it is a WonderfulBread or CommonBread

Reference:

Factory (object-oriented programming)

Simple Factory vs. Factory Method vs. Abstract Factory

JAVA Protected Modifier Testing

Simple Note

A little bit confused by protected modifier in JAVA:

Test cases:
https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/Commons/src/modifier/protectedtest

see derived class in packagea/packageb.

References

Controlling Access to Members of a Class

The protected modifier specifies that the member can only be accessed within its own package (as with package-private) and, in addition, by a subclass of its class in another package.

JMX Getting Started: Standard MBean

Simple Note

Introduction

From official site:

The JMX technology provides the tools for building distributed, Web-based, modular and dynamic solutions for managing and monitoring devices, applications, and service-driven networks. By design, this standard is suitable for adapting legacy systems, implementing new management and monitoring solutions, and plugging into those of the future. 

This article describe how to write JMX Standard MBeans.

Result

View demo on line
http://screencast.com/t/R80hAMjZcggm

Program

Test.java
The testing class to run.

TestBean.java
Test java bean, contains some operations and attribute.

TestBeanMBean.java
The interface for TestBean, according to JMX Standard MBean convention the name should be TestBeanMBean.

How to Run (Windows7/JDK6)

1. Download the bin/test  folder to some where.

2. Open cmd, go to the folder that contains the downloaded test folder.

3. Run it with "java -cp . test.Test".

4. Open jconsole.exe at your jdk/bin folder and try it.

Note:
1. If you didn't setup PATH properly (i.e. cannot execute java command any where) you can copy test folder to path_to_your_jdk_folder/bin.

2. You may need to change TMP folder to different location, please refer to the related thread on oracle community.

Reference

Standard MBean
http://docs.oracle.com/javase/tutorial/jmx/mbeans/standard.html

TMP Issue
https://community.oracle.com/thread/1176284?start=0&tstart=0

Download

Full project at github
https://github.com/benbai123/JSP_Servlet_Practice/tree/master/Practice/JAVA/JMX/MBeans/StandardMBean