C#中的工厂模型而不使用默认构造函数

Question

我一直在使用工厂模型创建子表单以添加到MDI表单.这是我一直在使用的代码:

    /// <summary>
    /// This uses the Factory Model to create the child node and then add it to the MDI Parent (this)
    /// </summary>
    /// <param name="childName">String class name of the child, i.e. RentalEase.PropertyGrid must extend Form or SingleInstance</param>
    /// <param name="singleInstance">bool If this class is to be a single instance and restricted to only on instance. Must extend SingleInstance</param>
    public void createChild(string childName, bool singleInstance) {
        if (singleInstance) {
            try {
                BaseAndSingleInstanceForm f = BaseAndSingleInstanceForm.getInstanceByType(this, Type.GetType(childName));
                    f.MdiParent = this;
                    f.Show();
                    f.BringToFront();
                    this.Refresh();
            } catch (Exception ex) {
                MessageBox.Show("Could not create child: " + ex.ToString());
            }
        } else {
            try {
                object o = Activator.CreateInstance(Type.GetType(childName));
                if (o is Form) {
                    Form f = (Form)o;
                    f.MdiParent = this;
                    f.Show();
                    f.BringToFront();
                    this.Refresh();
                } else {
                    throw new ArgumentException("Invalid Class");
                }
            } catch (Exception ex) {
                MessageBox.Show("Could not create child: " + ex.ToString());
            }
        }
    }

但是,出现了一种情况,我必须将一个整数参数添加到特定表单的构造函数中.我怎样才能改变它并使其反映出来,同时仍然保持模式的当前易用性(或几乎).

Answer 1

您可以Object[]向方法添加一个参数,该参数将表示要实例化的对象的构造函数的参数.然后,当您调用时,Activator.CreateInstance您可以传入该数组,并Activator尽力在您指定的类型上找到与Object数组中的类型匹配的构造函数.

这是我的意思的简化示例:

using System;

class Program
{
    static void Main()
    {
        Foo foo = (Foo)create("Foo", new Object[] { });
        Bar bar = (Bar)create("Bar", new Object[] { "hello bar" });
        Baz baz = (Baz)create("Baz", new Object[] { 2, "hello baz" });
    }

    static Object create(String typeName, Object[] parameters)
    {
        return Activator.CreateInstance(Type.GetType(typeName), parameters);
    }   
}

class Foo
{
    public Foo() { }
}

class Bar
{
    public Bar(String param1) { }
}

class Baz
{
    public Baz(Int32 param1, String param2) { }
}

我们有三种类型都有不同的构造函数 - 如果调用者负责发送类型名称,那么他们也将负责提供一个Objects满足非默认构造函数的数组.