策略模式

已经很久没有写博客了，今天写一篇关于策略模式的。通过交换两个数，来示例策略模式的使用。

package nuc.wss.operation;

/**
 * 交换两个数的接口
 *
 */
public interface Change {
    public void change(long a, long b);
}

package nuc.wss.operation.impl;

import nuc.wss.operation.Change;
/**
 * 通过加减交换两个数
 *
 */
public class AddOrSub implements Change {

    @Override
    public void change(long a, long b) {
        a = a + b;
        b = a - b;
        a = a - b;
        System.out.println("AddOrSub: a = " + a + " b = " + b);
    }
}

package nuc.wss.operation.impl;

import nuc.wss.operation.Change;

/**
 * 通过位运算交换两个数
 *
 */
public class BitChange implements Change {

    @Override
    public void change(long a, long b) {
        a = a ^ b;
        b = a ^ b;
        a = a ^ b;
        System.out.println("BitChange: a = " + a + " b = " + b);
    }
}

package nuc.wss.operation.impl;

import nuc.wss.operation.Change;

/**
 * 通过运算交换两个数
 *
 */
public class OperationChange implements Change {

    @Override
    public void change(long a, long b) {
        a = b + (b = a) * 0;
        System.out.println("OperationChange: a = " + a + " b = " + b);
    }
}

package nuc.wss.operation.impl;

import nuc.wss.operation.Change;

/**
 * 通过中间变量交换两个数
 *
 */
public class TempChange implements Change {

    @Override
    public void change(long a, long b) {
        long temp = a;
        a = b;
        b = temp;
        System.out.println("TempChange: a = " + a + " b = " + b);
    }

}

import nuc.wss.operation.Change;

/**
 * 通过此类操作Change子类
 *
 */
public class Context {
    private Change operation;
    
    public Context() {
        
    }
    
    public Context(Change operation) {
        this.operation = operation;
    }
    
    public void setOperation(Change operation) {
        this.operation = operation;
    }
    
    public void operate(long a, long b) {
        operation.change(a, b);
    }
}

import nuc.wss.operation.impl.AddOrSub;
import nuc.wss.operation.impl.BitChange;
import nuc.wss.operation.impl.OperationChange;
import nuc.wss.operation.impl.TempChange;

public class Main {
    public static void main(String[] args) {
        Context context = new Context();
        
        context.setOperation(new AddOrSub());
        context.operate(3, 4);
        
        context.setOperation(new BitChange());
        context.operate(3, 4);
        
        context.setOperation(new OperationChange());
        context.operate(3, 4);
        
        context.setOperation(new TempChange());
        context.operate(3, 4);
    }
}