C#设计模式/Command模式

原型

 1public class log
 2{
 3  public void Write(string target,string log)
 4  {
 5    //实现内容
          Console.WriteLine("Logging {0} to file {1}.",log,target);
 6  }
 7}
 8
 9log log=new log()
10  log.Write("error.log","log");

封装变化-封装用户请求的变化(需改变Write()方法）

 

public interface ILogWriter
    {
        void Write(string target,string logValue);
    }
public class DBLogWriter:ILogWriter
    {
        ILogWriter Members#region ILogWriter Members

        public void Write(string target, string logValue)
        {
            Console.WriteLine("Logging {0} to DB {1}.", logValue, target);            
        }

        #endregion        
    }
public class TxtLogWriter:ILogWriter
    {
        ILogWriter Members#region ILogWriter Members

        public void Write(string target, string logValue)
        {
            Console.WriteLine("Logging {0} to text file {1}.",logValue,target);            
        }

        #endregion
    }
 public class XmlLogWriter:ILogWriter
    {
        ILogWriter Members#region ILogWriter Members

        public void Write(string target, string logValue)
        {
            Console.WriteLine("Logging {0} to xml file {1}.", logValue, target);            
        }

        #endregion
    }   
public class Log
    {
        private ILogWriter m_log;
        public Log(ILogWriter log)
        {
            m_log = log;
        }
        public void Write(string target, string logValue)
        {
            m_log.Write(target,logValue);
        }
    }    
class Program
    {
        static void Main(string[] args)
        {
            Log lg=new Log(new DBLogWriter());
            lg.Write("DBLogWriter","DBLogValue");
            Log lg1 = new Log(new XmlLogWriter());
            lg1.Write("XmlLogWriter", "XmlLogValue");
            Log lg2 = new Log(new TxtLogWriter());
            lg2.Write("TxtLogWriter", "TxtLogValue");
            Console.ReadLine();
        }
    }