MDI子窗体修改MDI父窗体中的变量，来实现子窗体实例的只出现一次，各位高手请大家指点一下，刚学习C#

[huazaimh]

在主窗体中，我写了这样的语句，定义了一个变量

public StorageFrm frmStorage;

private void DressManageItem_Click(object sender, EventArgs e)
{
if (frmStorage == null)
{
frmStorage = new StorageFrm();
frmStorage.Show();
}
else
{
frmStorage.Activate();
frmStorage.WindowState = FormWindowState.Normal;
frmStorage.BringToFront();
}
}
这里是可以实现唯StorageFrm窗体只弹出一次，可是关闭之后，再想弹出就不可以了，我知道用全局变量应该是可以实现的，请问各位高手，有没有别的办法，不用全局变量，能不能实现？谢谢!

[lijun7788]

写一个Config类,在Config中
class Config
{
private static StorageFrm frmStorage;
public static void ShowStorageFrm(){
if(frmStorage==null)
frmStorage=new StorageFrm();
frmStorage.show();
}
}

编写StorageFrm窗体的FormeClosing事件
this.Hide();
e.Cancel=True;
让窗体不关闭，只是隐藏

[huazaimh]

up

[gengxin_914]

参考：
http://hi.baidu.com/leader_bin/blog/item/755ff14c353db3ffd72afc85.html
http://topic.csdn.net/t/20050922/16/4287256.html

[冷月孤峰]

#region 不重复打开MDI子窗体
        /// <summary>
        /// 不重复打开MDI子窗体
        /// 调用：this.OpenMDIWindow(typeof(窗体名).ToString());
        /// </summary>
        /// <param name="ChildTypeString">窗体名称(typeof(FormName).ToString())</param>
        private void OpenMDIWindow(string ChildTypeString)
        {
            Form myChild = null;
            if (!ContainMDIChild(ChildTypeString))
            {
                // Get current process assembly
                Assembly assembly = Assembly.GetExecutingAssembly();
                // Create data type using type string
                Type typForm = assembly.GetType(ChildTypeString);
                // Create object using type's "InvokeMember" method
                Object obj = typForm.InvokeMember(
                    null,
                    BindingFlags.DeclaredOnly |
                    BindingFlags.Public | BindingFlags.NonPublic |
                    BindingFlags.Instance | BindingFlags.CreateInstance,
                    null,
                    null,
                    null);
                // Show child form 
                if (obj != null)
                {
                    this.Refresh();
                    //Form frmTip = LoadTip.ShowTipForm(this, "正在加载窗体");

                    myChild = obj as Form;
                    myChild.MdiParent = this;
                    myChild.WindowState = FormWindowState.Maximized;
                    myChild.Show();
                    myChild.Focus();

                    //frmTip.Close();

                }
            }
        }

        /// <summary>
        /// Search mdi child form by specific type string
        /// </summary>
        /// <param name="ChildTypeString"></param>
        /// <returns></returns>
        private bool ContainMDIChild(string ChildTypeString)
        {
            Form myMDIChild = null;
            foreach (Form f in this.MdiChildren)
            {
                if (f.GetType().ToString() == ChildTypeString)
                {
                    // found it 
                    myMDIChild = f;
                    break;
                }
            }
            // Show the exist form
            if (myMDIChild != null)
            {
                myMDIChild.TopMost = true;
                myMDIChild.Show();
                myMDIChild.Focus();
                return true;
            }
            else
            {
                return false;
            }
        }
        #endregion 

调用：

this.OpenMDIWindow(typeof(窗体名).ToString());

[qq69524898]

期待中,帮顶一下.

[wuyq11]

private T OpenUniqueMDIChildWindow<T>(Form mdiParent) where T : Form, new()
{
foreach (Form subForm in mdiParent.MdiChildren)
{
if (subForm.GetType().Equals(typeof(T)))
{
subForm.Activate();
return subForm as T;
}
}
T newForm = new T();
newForm.MdiParent = mdiParent;
newForm.Show();
return newForm;
}
或
private Form FindChildRenForm(Type type)
{
Form frm = null;
foreach(Form f in this.MdiChildren)
{
if ( f.GetType() == type )
{
frm = f;
if ( frm.WindowState != FormWindowState.Maximized )
frm.WindowState = FormWindowState.Maximized;
frm.Activate();
break;
}
}
return frm;
}

[ZJ159]

顶

[huazaimh]

[Quote=引用 6 楼 wuyq11 的回复:]
private T OpenUniqueMDIChildWindow <T>(Form mdiParent) where T : Form, new()
{
foreach (Form subForm in mdiParent.MdiChildren)
{
if (subForm.GetType().Equals(typeof(T)))
{
subForm.Activate();
return subForm as T;
}
}
T newForm = new T();
newForm.MdiParent = mdiParent;
newForm.Show();
return newF…
[/Quote]
能行不？

[huazaimh]

private static 窗体 instance = null;
//添加一个属性
public static 窗体 Instance
{
set{
}
get{
if(instance == null){
new 窗体();
}
return instance;
}
}在窗体的构造函数中加入如下代码
instance = this;创建窗体Closed事件
private void 窗体_FormClosed(object sender, FormClosedEventArgs e)
{
instance = null;
}
使用方法:
在要调用该窗体的地方加入如下代码
窗体 myfrm = 窗体.Instance;
myfrm.Show();
myfrm.Activate();

该办法不错，挺简单的，谢谢!

[pricks]

运用单例模式。

[wlzx21]

用集合来存储所有子窗体实例(或指定一个什么标记),再运行子窗体实例时,先判断相应
实例是否在集合存在,若存在,则不在运行;在关闭子窗体,从集合中将相应实例(或标记)删除