C#中调用API函数RegisterHotKey注册多个系统热键

要设置快捷键必须使用user32.dll下面的两个方法。
bool registerhotkey( //注册系统热键的api函数
　hwnd hwnd,
　int id,
　uint fsmodifiers,
　uint vk
);
 
bool unregisterhotkey( //删除系统热键的api函数
　hwnd hwnd,
　int id
);
 
在c#中引用命名空间system.runtime.interopservices;来加载非托管类user32.dll
using system;
using system.collections.generic;
using system.componentmodel;
using system.data;
using system.drawing;
using system.text;
using system.windows.forms;
 
namespace hotkey
{
 
    public enum keymodifiers //组合键枚举
    {
        none = 0,
        alt = 1,
        control = 2,
        shift = 4,
        windows = 8
    }
 
    public partial class form1 : form
    {
        /*
         * registerhotkey函数原型及说明：
         * bool registerhotkey(
         * hwnd hwnd,         // window to receive hot-key notification
         * int id,            // identifier of hot key
         * uint fsmodifiers, // key-modifier flags
         * uint vk            // virtual-key code);
         * 参数 id为你自己定义的一个id值
         * 对一个线程来讲其值必需在0x0000 - 0xbfff范围之内,十进制为0~49151
         * 对dll来讲其值必需在0xc000 - 0xffff 范围之内,十进制为49152~65535
         * 在同一进程内该值必须唯一参数 fsmodifiers指明与热键联合使用按键
         * 可取值为：mod_alt mod_control mod_win mod_shift参数，或数字0为无，1为alt,2为control，4为shift，8为windows
         * vk指明热键的虚拟键码
         */
 
        [system.runtime.interopservices.dllimport("user32.dll")] //申明api函数
        public static extern bool registerhotkey(
         intptr hwnd, // handle to window
         int id, // hot key identifier
         uint fsmodifiers, // key-modifier options
         keys vk // virtual-key code
        );
        [system.runtime.interopservices.dllimport("user32.dll")] //申明api函数
        public static extern bool unregisterhotkey(
         intptr hwnd, // handle to window
         int id // hot key identifier
        );
        public form1()
        {
            initializecomponent();
        }
        private void processhotkey(message m) //按下设定的键时调用该函数
        {
            intptr id = m.wparam; //intptr用于表示指针或句柄的平台特定类型
            //messagebox.show(id.tostring());
            string sid = id.tostring();
            switch (sid)
            {
                case "100":
                    messagebox.show("调用a函数");
                    break;
                case "200":
                    messagebox.show("调用b函数");
                    break;
            }
        }
        private void form1_load(object sender, eventargs e)
        {
            //handle为当前窗口的句柄,继续自control.handle,control为定义控件的基类
            //registerhotkey(handle, 100, 0, keys.a); //注册快捷键,热键为a
            //registerhotkey(handle, 100, keymodifiers.alt | keymodifiers.control, keys.b);//这时热键为alt+ctrl+b
            //registerhotkey(handle, 100, 1, keys.b); //1为alt键，热键为alt+b
            registerhotkey(handle, 100, 2,keys.a); //定义热键为alt+tab，这里实现了屏幕系统alt+tab键
            registerhotkey(handle, 200, 2, keys.b); //注册2个热键,根据id值100,200来判断需要执行哪个函数
        }
 
        private void button1_click(object sender, eventargs e) //重新设置热键
        {
            unregisterhotkey(handle, 100);//卸载快捷键
            registerhotkey(handle, 100, 2, keys.c); //注册新的快捷键，参数0表示无组合键
        }
 
        private void form1_formclosing(object sender, formclosingeventargs e) //退出程序时缷载热键
        {
            unregisterhotkey(handle, 100);//卸载第1个快捷键
            unregisterhotkey(handle, 200); //缷载第2个快捷键
        }
 
        //重写wndproc()方法，通过监视系统消息，来调用过程
        protected override void wndproc(ref message m)//监视windows消息
        {
            const int wm_hotkey = 0x0312;//如果m.msg的值为0x0312那么表示用户按下了热键
            switch (m.msg)
            {
                case wm_hotkey:
                    processhotkey(m);//按下热键时调用processhotkey()函数
                    break;
            }
            base.wndproc(ref m); //将系统消息传递自父类的wndproc
        }
    }
}