用java编写一个策略模式
时间: 2023-08-25 14:07:42 浏览: 48
策略模式是一种行为设计模式,它定义了一系列算法,并将每个算法封装起来,使它们可以互换。这种模式使得算法可以独立于使用它的客户端而变化。
下面是一个使用 Java 编写的策略模式示例:
首先,我们需要定义一个接口,它包含了所有算法必须实现的方法:
```java
public interface Strategy {
public int doOperation(int num1, int num2);
}
```
然后,我们定义一些具体的算法实现:
```java
public class OperationAdd implements Strategy {
@Override
public int doOperation(int num1, int num2) {
return num1 + num2;
}
}
public class OperationSubtract implements Strategy {
@Override
public int doOperation(int num1, int num2) {
return num1 - num2;
}
}
public class OperationMultiply implements Strategy {
@Override
public int doOperation(int num1, int num2) {
return num1 * num2;
}
}
```
接下来,我们需要创建一个 Context 类,它将使用具体的策略来执行算法:
```java
public class Context {
private Strategy strategy;
public Context(Strategy strategy){
this.strategy = strategy;
}
public int executeStrategy(int num1, int num2){
return strategy.doOperation(num1, num2);
}
}
```
最后,我们可以使用 Context 类来执行不同的算法:
```java
public class Main {
public static void main(String[] args) {
Context context = new Context(new OperationAdd());
System.out.println("10 + 5 = " + context.executeStrategy(10, 5));
context = new Context(new OperationSubtract());
System.out.println("10 - 5 = " + context.executeStrategy(10, 5));
context = new Context(new OperationMultiply());
System.out.println("10 * 5 = " + context.executeStrategy(10, 5));
}
}
```
输出结果为:
```
10 + 5 = 15
10 - 5 = 5
10 * 5 = 50
```