搞搞就懂

interface ICompressAlgorithm
{
    // 檔案壓縮
    void Compress();
}

class NormalCompressAlgorithm : ICompressAlgorithm
{
    public void Compress()
    {
        Console.WriteLine("普通壓縮");
    }
}

class MidLevelCompressAlgorithm : ICompressAlgorithm
{
    public void Compress()
    {
        Console.WriteLine("中級壓縮");
    }
}

class HighLevelCompressAlgorithm : ICompressAlgorithm
{
    public void Compress()
    {
        Console.WriteLine("高級壓縮");
    }
}

class Zipper
{
    // Fields
    private ICompressAlgorithm _compressAlgorithm;


    // Constructors
    public Zipper(ICompressAlgorithm compressAlgorithm)
    {
        _compressAlgorithm = compressAlgorithm;
    }


    // Methods
    public void Compress()
    {
        if (_compressAlgorithm != null)
            _compressAlgorithm.Compress();
    }
}

static void Main(string[] args)
{
	// 檔案壓縮產品(三種)
    Zipper normalZipper;
    Zipper noAdZipper;
    Zipper enterpriseZipper;

    // 免費版: 注入普通壓縮演算法
    Console.WriteLine("Normal Zipper:");
    normalZipper = new Zipper(new NormalCompressAlgorithm());
    normalZipper.Compress();

    // 去廣告板: 注入中效壓縮演算法
    Console.WriteLine("No Ad Zipper:");
    noAdZipper = new Zipper(new MidLevelCompressAlgorithm());
    noAdZipper.Compress();

    // 企業版: 注入高效壓縮演算法
    Console.WriteLine("Enterprise Zipper:");
    enterpriseZipper = new Zipper(new HighLevelCompressAlgorithm());
    enterpriseZipper.Compress();

    Console.ReadKey();
}