用SendMessage用于进程间通信使用自定义消息，String含在Struct里，接收方却得到null？急
用SendMessage用于进程间通信使用自定义消息，String含在Struct里，接收方却得到null？
在网上找了一下可以用“结构体封装string字段”，但是我试过，接收方可以收到消息，得到的String却是null，不知道为什么？如果要传其它数据类型，如byte，int之类的应该怎么传送？
发送方：
public const int WM_USER = 0x500;
public const int RF_CMD = WM_USER + 13;
public struct RFDataStruct
{
public int rfLength;
public string rfData;
}
byte rfCmd = 0;
[DllImport("user32.dll")]
public static extern bool SendMessage(IntPtr hWnd, int Msg, int wParam, ref RFDataStruct lparam);
private void buttonSend_Click(object sender, EventArgs e)
{
Process[] vProcesses = Process.GetProcessesByName("PorcessReceiveUserDefinedMessageDemo"); // 查询目标进程
if (vProcesses.Length <= 0)
vProcesses = Process.GetProcessesByName("PorcessReceiveUserDefinedMessageDemo.vshost"); //Debug调试进程
if (vProcesses.Length <= 0)
{
MessageBox.Show("目标进程没有找到！");
return;
}
if (comboBoxRF.Text == comboBoxRF.Items[0].ToString()) rfCmd = 0;
else if (comboBoxRF.Text == comboBoxRF.Items[1].ToString()) rfCmd = 1;
else if (comboBoxRF.Text == comboBoxRF.Items[2].ToString()) rfCmd = 2; //SelectedText不行,始终为空
else rfCmd = 3;
string rfCmdString = rfCmd.ToString("X2");
RFDataStruct rfMessage = new RFDataStruct();
rfMessage.rfData = rfCmdString;
rfMessage.rfLength = rfMessage.rfData.Length;
foreach (Process vProcess in vProcesses)
{
bool returnValue3 = SendMessage(vProcess.MainWindowHandle, RF_CMD, 1, ref rfMessage);
}
}
public const int WM_USER = 0x500;
public const int RF_CMD = WM_USER + 13;
public struct RFDataStruct
{
public string rfData;
public int rfLength;
}
protected override void DefWndProc(ref Message m)
{
switch (m.Msg)
{
case RF_CMD:
RFDataStruct rfDataStruct = new RFDataStruct();
Type type = rfDataStruct.GetType();
rfDataStruct = (RFDataStruct)m.GetLParam(type);
string rfCmd = rfDataStruct.rfData;
//string rfCmd = Marshal.PtrToStringBSTR(m.LParam);
textBox1.Text = rfCmd;
break;
default:
base.DefWndProc(ref m);
break;
}
//base.WndProc(ref m);
}
//自定义的消息
public const int USER = 0x500;
public const int MYMESSAGE = USER + 1;
public Form2()
{
InitializeComponent();
}
IntPtr HD;
public Form2(IntPtr hd)
{
InitializeComponent();
HD = hd;
}
private void button1_Click(object sender, EventArgs e)
{
IntPtr ptr = FindWindow(null, "Form1");//获取接收消息的窗体句柄
//消息构建
My_lParam m = new My_lParam();
m.s = textBox1.Text;
m.i = m.s.Length;
SendMessage(ptr, MYMESSAGE, 1, ref m);//发送消息
}
public struct My_lParam
{
public int i;
public string s;
}
//消息发送API
[DllImport("User32.dll", EntryPoint = "SendMessage")]
private static extern int SendMessage(
IntPtr hWnd, // 信息发往的窗口的句柄
int Msg, // 消息ID
int wParam, // 参数1
ref My_lParam lParam
);
[DllImport("User32.dll", EntryPoint = "FindWindow")]
private extern static IntPtr FindWindow(string lpClassName, string lpWindowName);
public const int USER = 0x500;
public const int MYMESSAGE = USER + 1;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Form2 f = new Form2(this.Handle);
f.Show();
}
///重写窗体的消息处理函数DefWndProc，从中加入自己定义消息 MYMESSAGE 的检测的处理入口
protected override void DefWndProc(ref Message m)
{
switch (m.Msg)
{
//接收自定义消息MYMESSAGE，并显示其参数
case MYMESSAGE:
Form2.My_lParam ml = new Form2.My_lParam();
Type t = ml.GetType();
ml = (Form2.My_lParam)m.GetLParam(t);
label1.Text = ml.s;
//SendCustomMessage.SENDDATASTRUCT myData = new SendCustomMessage.SENDDATASTRUCT();//这是创建自定义信息的结构
//Type mytype = myData.GetType();
//myData = (SendCustomMessage.SENDDATASTRUCT)m.GetLParam(mytype);//这里获取的就是作为LParam参数发送来的信息的结构
//textBox1.Text = myData.lpData; //显示收到的自定义信息
break;
default:
base.DefWndProc(ref m);
break;
}
}
