Code examples on the definition and usage of template method patterns in Java classic design patterns

This article mainly introduces the template method pattern of Java's classic design pattern, briefly explains the principle and definition of the template method pattern, and analyzes the specific usage of the java template method pattern in the form of examples. Friends in need can refer to it.

The examples in this article describe the template method pattern of Java design patterns. Share it with everyone for your reference, the details are as follows:

In our lives, many things include specific steps. If you go to a bank to handle business, the usual sequence of steps is: take a number –> fill in the form –> wait for your number to be called –> handle the business. Among these steps, some remain unchanged, such as taking a number, which must be taken by everyone, but some have to change, such as filling out forms, but depending on the business, the documents to be filled out are different. Another example is when we go out to eat, the general steps are: order -> wait -> eat -> pay. The same pattern can also be found. There are countless such things.

During project development, we may also encounter such a situation. Multiple functional modules may have similar or identical operation steps, but one link or step is different. We can extract one or Multiple common parent classes (templates) allow subclasses to implement specific methods. Let's take going to the bank to handle business as an example:

Simulated abstract class:

/**
* 模板方法模式的模板框架(以去银行办理业务为例)
* @description：
*/
public abstract class TempletBankFrame {
/* 比如：去柜台办理银行卡业务* */
public final void handleBankCard() {
/* 第一步：进入银行大厅取号* */
takeNumber();
/* 第二步：填写办理业务的相关单据* */
if(!isNeedThisMethod()){//特殊情况可以添加判断，如我之前有填写好单子，那今天就不必再填写了
writeBill();
}
/* 第三步：等待工作人员叫号* */
waitCall();
/* 第四步：办理业务* */
handleCard();
}
/* 取号步骤是不需要更改的，所以我们用private修饰* */
private void takeNumber() {
  System.out.println("办理银行业务请取号！");
}
/* 办理的业务不同，填写的内容不同，所以我们用protected修饰，让子类去处理具体业务* */
protected abstract void writeBill();
/* 等待叫号步骤也是不需要更改的，所以我们用private修饰* */
private void waitCall() {
  System.out.println("办理银行业务请取号！");
}
/* 办理的业务不同，用protected修饰，让子类去处理具体业务* */
protected abstract void handleCard();
/*定义一个钩子方法：由抽象类声明并实现，而子类会加以扩展。通常抽象类给出的实现是一个空实现，作为方法的默认实现。**/
protected abstract boolean isNeedThisMethod();
}

Concrete implementation class: For example, handling money withdrawals

/**
* 办理取钱业务
* @description：
*/
public class GetMoney extends TempletBankFrame {
@Override
protected void writeBill() {
  System.out.println("我在填写取钱的单据！");
}
@Override
protected void handleCard() {
  System.out.println("我要取500万大洋");
}
@Override
protected boolean isNeedThisMethod() {
  System.out.println("我已经填写过单子，今天就直接等待叫号了吧！");
  return true;
}
}

Specific implementation class: For example, I am going to apply for a bank card

/**
* 办理银行卡
* @description：
*/
public class TackCard extends TempletBankFrame {
@Override
protected void writeBill() {
  System.out.println("我填写的是办理银行卡单据");
}
@Override
protected void handleCard() {
  System.out.println("我在办卡，即将完成！");
}
@Override
protected boolean isNeedThisMethod() {
  return false;
}
}

Test class

/**
* 模板方法模式测试类
* @description：
*/
public class Test {
public static void main(String[] args) {
GetMoney money=new GetMoney();
money.handleBankCard();//调用模板中的办理业务方法
System.out.println("———–分隔线—————-");
TackCard card=new TackCard();
card.handleBankCard();
}
}

The final output result:

办理银行业务请取号！
我已经填写过单子，今天就直接等待叫号了吧！
办理银行业务请取号！
我要取500万大洋
———–分隔线—————-
办理银行业务请取号！
我填写的是办理银行卡单据
办理银行业务请取号！
我在办卡，即将完成！

The above is the detailed content of Code examples on the definition and usage of template method patterns in Java classic design patterns. For more information, please follow other related articles on the PHP Chinese website!