Design Pattern - Template Method（Java）

清疚 2022-05-18 10:11 108阅读 0赞

分享一个大牛的人工智能教程。零基础！通俗易懂！风趣幽默！希望你也加入到人工智能的队伍中来！请点击[http://www.captainbed.net][http_www.captainbed.net]

# Definition #

Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.

# Participants #

The classes and/or objects participating in this pattern are:

*  **AbstractClass** **(DataObject)**
    
     *  Defines abstract *primitive operations* that concrete subclasses define to implement steps of an algorithm
     *  Implements a template method defining the skeleton of an algorithm. The template method calls primitive operations as well as operations defined in AbstractClass or those of other objects
 *  **ConcreteClass** **(CustomerDataObject)**
    
     *  Implements the primitive operations or carry out subclass-specific steps of the algorithm

# Sample Code in Java #

This structural code demonstrates the Template Method which provides a skeleton calling sequence of methods. One or more steps can be deferred to subclasses which implement these steps without changing the overall calling sequence.

package chimomo.learning.java.designpattern.templatemethod.sample;
    
    /**
     * The 'AbstractClass' abstract class
     *
     * @author Chimomo
     */
    abstract class AbstractClass {
    
        /**
         * Primitive operation 1
         */
        public abstract void primitiveOperation1();
    
        /**
         * Primitive operation 2
         */
        public abstract void primitiveOperation2();
    
        /**
         * Template method
         */
        void templateMethod() {
            this.primitiveOperation1();
            this.primitiveOperation2();
            System.out.println();
        }
    
    }

package chimomo.learning.java.designpattern.templatemethod.sample;
    
    /**
     * A 'ConcreteClass' class
     *
     * @author Chimomo
     */
    class ConcreteClassA extends AbstractClass {
    
        /**
         * Primitive operation 1
         */
        @Override
        public void primitiveOperation1() {
            System.out.println("ConcreteClassA.primitiveOperation1()");
        }
    
        /**
         * Primitive operation 2
         */
        @Override
        public void primitiveOperation2() {
            System.out.println("ConcreteClassA.primitiveOperation2()");
        }
    
    }

package chimomo.learning.java.designpattern.templatemethod.sample;
    
    /**
     * A 'ConcreteClass' class
     *
     * @author Chimomo
     */
    class ConcreteClassB extends AbstractClass {
    
        /**
         * Primitive operation 1
         */
        @Override
        public void primitiveOperation1() {
            System.out.println("ConcreteClassB.primitiveOperation1()");
        }
    
        /**
         * Primitive operation 2
         */
        @Override
        public void primitiveOperation2() {
            System.out.println("ConcreteClassB.primitiveOperation2()");
        }
    
    }

package chimomo.learning.java.designpattern.templatemethod.sample;
    
    /**
     * Startup class for Sample Template Method design pattern
     *
     * @author Chimomo
     */
    class Program {
    
        /**
         * Entry point into console application
         *
         * @param args The arguments
         */
        public static void main(String[] args) {
            AbstractClass aA = new ConcreteClassA();
            aA.templateMethod();
    
            AbstractClass aB = new ConcreteClassB();
            aB.templateMethod();
        }
    
    }
    
    /* ------ Running Results ------
    ConcreteClassA.primitiveOperation1()
    ConcreteClassA.primitiveOperation2()
    
    ConcreteClassB.primitiveOperation1()
    ConcreteClassB.primitiveOperation2()
    
    
    */

[http_www.captainbed.net]: http://www.captainbed.net/troubleshooter