命令模式实例计算器

矫情吗；* 2023-10-06 10:21 42阅读 0赞

使用命令模式岩石和简单的计算器功能,并允许执行UNDO和REDO

UML图  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE1NzE5NjEz_size_16_color_FFFFFF_t_70]  
代码

package 命令模式;
    
    public class Caculator {
        
    private int total;
     
    public Caculator() {
        
    	
    	this.total = 0;
    }
     
    public void Operation(char op,int num)
    {
        switch(op)
    	{
        case '+':total+=num;break;
    	case '-':total-=num;break;
    	case '*':total*=num;break;
    	case '/':total/=num;break;
    }
    System.out.println(op+" "+num+"="+total);
     
    }
    }

package 命令模式;
    
    public class CalCommand extends Command {
        
     
    	public CalCommand(Caculator cal, char op, int num) {
        
    		super(cal, op, num);
    		
    	}
     
    	@Override
    	public void Execute() {
        
    	cal.Operation(op, num);
    	}
     
    	@Override
    	public void UnExecute() {
        
    		cal.Operation(undo(op), num);
     
    	}
    	private char undo(char op)
    	{
        char undo=' ';
    	switch(op)
    	{
        case '+':undo='-';break;
    	case '-':undo='+'; break;
    	case '*':undo='/';break;
    	case '/': undo='*'; break;
    	}
    	return undo;
    	}
     
    }

package 命令模式;
    
    public abstract class Command {
        
    	protected Caculator cal;
    	protected char op;;
    	protected int num;
    	
    public Command(Caculator cal, char op, int num) {
        
    		
    		this.cal = cal;
    		this.op = op;
    		this.num = num;
    	}
    public abstract void Execute();
    public abstract void UnExecute();
    }

package 命令模式;
    
    import java.util.ArrayList;
     
    public class User {
        
    private ArrayList<Command>commands=new ArrayList<Command>();
    private int count=0;
    public void Compute(Command command)
    {
        command.Execute();
    count++;
    commands.add(command);
     
    }
    public void Redo(int levels)
    {
        for(int i=0;i<levels;i++)
    {
        if(count<commands.size())
    	{
        count++;
    	commands.get(count-1).Execute();
     
    }
    }
    }
    public void Undo(int levels)
    {
        for(int i=0;i<levels;i++)
    	if(count>0)
    	{
        
    		commands.get(count-1).UnExecute();
    	count--;
    	}
    }
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE1NzE5NjEz_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200604125300467.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE1NzE5NjEz,size_16,color_FFFFFF,t_70