Detailed case explanation of Java 23 design patterns: template method pattern (with code)

Definition

Defines the framework of operations in an algorithm, deferring some steps to subclasses. This allows subclasses to redefine certain specific steps of the algorithm without changing the algorithm structure.

Roles

The role division of this design pattern is relatively simple

• Abstract template class

• Concrete template class

The abstract template class contains several methods: template method, concrete method, abstract method, and hook method.

• Template method

determines the implementation steps of the algorithm. This method calls specific methods, abstract methods to be implemented, and hook methods. wait. It is a template for algorithm execution.

• Concrete method

The specific method is the more stable part of the algorithm, so the specific implementation of the method is given in the abstract class.

• Abstract method

Abstract method is exactly the method mentioned in the definition that is delayed to the implementation of the subclass.

• Hook method

General template methods will provide a default implementation, and subclasses will override and rewrite this method depending on the situation.

UML

Implementation process

/**
 * Created by tiantian on 2018/7/28
 */public abstract class AbstractTemplateMethod {

    public void templateMethod() {
        implementedMethod();
        abstractMethod();
        hookMethod();        // ... more than method invoke
    }    public void anotherTemplateMethod() {        // do other things
    }    public abstract void abstractMethod();    public void hookMethod() {}    public void implementedMethod() {
        System.out.println("I have been implemented in TemplateMethod class.");
    }    // ... more than method abstract or implemented.}

/**
 * Created by tiantian on 2018/7/28
 */public class ConcreteTempleteMethod extends AbstractTemplateMethod {
    @Override
    public void abstractMethod() {
        System.out.println("Do something");
    }    @Override
    public void hookMethod() {
        System.out.println("Do something in hookMethod");
    }
}

Definition

Define the operation framework in an algorithm, and some steps Defer to subclasses. This allows subclasses to redefine certain specific steps of the algorithm without changing the algorithm structure.

Roles

The role division of this design pattern is relatively simple

• Abstract template class

• Specific template Class

The abstract template class contains several methods: template method, concrete method, abstract method, and hook method.

• Template method

determines the implementation steps of the algorithm. This method calls specific methods, abstract methods to be implemented, and hook methods. wait. It is a template for algorithm execution.

• Concrete method

The specific method is the more stable part of the algorithm, so the specific implementation of the method is given in the abstract class.

• Abstract method

Abstract method is exactly the method mentioned in the definition that is delayed to the implementation of the subclass.

• Hook method

General template methods will provide a default implementation, and subclasses will override and rewrite this method depending on the situation.

UML

Implementation process

/**
 * Created by tiantian on 2018/7/28
 */public abstract class AbstractTemplateMethod {

    public void templateMethod() {
        implementedMethod();
        abstractMethod();
        hookMethod();        // ... more than method invoke
    }    public void anotherTemplateMethod() {        // do other things
    }    public abstract void abstractMethod();    public void hookMethod() {}    public void implementedMethod() {
        System.out.println("I have been implemented in TemplateMethod class.");
    }    // ... more than method abstract or implemented.}

/**
 * Created by tiantian on 2018/7/28
 */public class ConcreteTempleteMethod extends AbstractTemplateMethod {
    @Override
    public void abstractMethod() {
        System.out.println("Do something");
    }    @Override
    public void hookMethod() {
        System.out.println("Do something in hookMethod");
    }
}

Related articles:

Java design patterns-design patterns Six principles

JAVA design pattern factory pattern (simple factory pattern factory method pattern)

Related videos:

Design Patterns

The above is the detailed content of Detailed case explanation of Java 23 design patterns: template method pattern (with code). For more information, please follow other related articles on the PHP Chinese website!