单列模式

 

主窗体代码如下:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SingleModel
...{
    public partial class Form1 : Form
    ...{
        public Form1()
        ...{
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        ...{
            frmSingle.Instances.Show();
        }
    }
} 

 

SingleModel.cs代码如下:

 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SingleModel
...{
    public partial class frmSingle : Form
    ...{
        //原来的公有构造方法
        //public frmSingle()
        //{
        //    InitializeComponent();
        //}

        //定义static frmSingle instances
        private static frmSingle instances;

        //更改成私有构造方法
        private frmSingle()
        ...{
            InitializeComponent();
        }

        /**//// <summary>
        /// 开放属性，以得到此窗体
        /// </summary>
        public static frmSingle Instances
        ...{
            get
            ...{
                if (instances == null)
                    instances = new frmSingle();
                else
                    instances.Activate();
                return instances;

            }
        }

        /**//// <summary>
        /// 声明instances为null
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void frmSingle_FormClosing(object sender, FormClosingEventArgs e)
        ...{
            instances = null;
        }



    }
}

 

源工程位置:http://download.youkuaiyun.com/source/369010