Design Patterns-Template method patterns (template methods pattern) detailed

Template Method Mode (template methods pattern) detailed

This article address: Http://blog.csdn.net/caroline_wendy

template Approach Pattern: Defines the skeleton of an algorithm in a method, and delays some steps into subclasses. \ template

Template methods allow subclasses to redefine certain steps in an algorithm without changing the structure of the algorithm.

Template methods can be hooks (hooks), a method that is declared in an abstract class, but only empty or default implementations.

The presence of hooks allows subclasses to have the ability to hook up different points of the algorithm.

Framework for abstract classes:

/**
 * @time June 18, 2014 * * *
package template_method;

/**
 * @author C.l.wang
 * * *
 /Public
abstract class AbstractClass {
	
	final void Templatemethod () {
		PrimitiveOperation1 ();
		PrimitiveOperation2 ();
		Concreteoperation ();
		Hook ();
	}
	
	abstract void PrimitiveOperation1 ();
	
	abstract void PrimitiveOperation2 ();
	
	final void Concreteoperation () {
		
	}
	
	void Hook () {}
}

Object-oriented principles:

Hollywood rule: Don't call us, we'll call you.

Specific methods:

1. Abstraction Class (abstract Class), containing template methods (template method), Abstract Operations (Abstracts operation),

specific operations (concrete operation), and hooks (hook).

/**
 * @time June 18, 2014 * * *
package template_method;

/**
 * @author C.l.wang
 * * *
 /Public
abstract class Caffeinebeverage {
	
	final void Preparerecipe () {// Template Method
		Boilwater ();
		Brew ();
		Pourincup ();
		if (customerwantscondiments ()) {
			addcondiments ();
		}
	}
	
	abstract void Brew (); Abstract
	
	void addcondiments ();
	
	void Boilwater () {//specific operation
		System.out.println ("boiling water");
	}
	
	void Pourincup () {
		System.out.println ("pouring into Cup");
	}
	
	Boolean customerwantscondiments () {//Hook return
		true;
	}
	
}

2. Specific Class (concrete Class), Inheritance (extend) abstract class (abstract class).

/** * @time June 18, 2014 * * * Package template_method;
Import Java.io.BufferedReader;
Import java.io.IOException;

Import Java.io.InputStreamReader; /** * @author C.l.wang * */public class Coffeewithhook extends Caffeinebeverage {/* (non-javadoc) * @see template _method.  Caffeinebeverage#brew () */@Override void Brew () {//TODO auto-generated Method stub System.out.println ("Dripping
	Coffee through filter "); }/* (non-javadoc) * @see Template_method. Caffeinebeverage#addcondiments () */@Override void addcondiments () {//TODO auto-generated method stub System.out
	. println ("Adding Sugar and Milk");
		
		public Boolean customerwantscondiments () {//Hook String answer = Getuserinput ();
		if (Answer.tolowercase (). StartsWith ("Y")) {return true;
		else {return false;
		
		} private String Getuserinput () {string answer = NULL;
		
		System.out.println ("Would You like milk and sugar with your coffee (y/n)"); BufferedReader in = new BufFeredreader (New InputStreamReader (system.in));
		try {answer = In.readline ();
		catch (IOException IoE) {System.out.println ("IO error trying to read your answer");
		} if (answer = null) {return "no";
	return answer;

}/** * @time June 18, 2014 * * * Package template_method;
Import Java.io.BufferedReader;
Import java.io.IOException;

Import Java.io.InputStreamReader; /** * @author C.l.wang * */public class Teawithhook extends Caffeinebeverage {/* (non-javadoc) * @see Template_me Thod.  Caffeinebeverage#brew () */@Override void Brew () {//TODO auto-generated Method Stub System.out.println ("Steeping
	The tea "); }/* (non-javadoc) * @see Template_method. Caffeinebeverage#addcondiments () */@Override void addcondiments () {//TODO auto-generated method stub System.out
	. println ("adding Lemon");
		
		public Boolean customerwantscondiments () {String answer = getuserinput (); if (Answer.tolowercase (). StartsWith ("Y")) {RETurn true;
		else {return false;
		
		} private String Getuserinput () {string answer = NULL;
		
		System.out.println ("Would you like lemon with your tea (y/n)");
		
		BufferedReader in = new BufferedReader (new InputStreamReader (system.in));
		try {answer = In.readline ();
		catch (IOException IoE) {System.out.println ("IO error trying to read your answer");
		} if (answer = null) {return "no";
	return answer;
 }
	
}

3. Test ClassContains Hooks (Hook) Operation.

/**
 * @time June 18, 2014 * * *
package template_method;

/**
 * @author C.l.wang * */Public
class Beveragetestdrive {

	/**
	 * @param args
	 * * Public
	static void Main (string[] args) {
		//TODO auto-generated method stub
		Teawithhook teahook = new TEAW Ithhook ();
		Coffeewithhook Coffeehook = new Coffeewithhook ();
		
		System.out.println ("\nmaking tea ...");
		Teahook.preparerecipe ();
		
		System.out.println ("\nmaking coffee ...");
		Coffeehook.preparerecipe ();
	}

4. Output:

Making tea ...
Boiling water
steeping the tea
pouring into cup Would your like lemon and
your tea (y/n)? 
Y
adding Lemon

making coffee ...
Boiling water
dripping Coffee through filter
pouring into Cup
Would your like milk and sugar with your Coffee (y/n)? 
N