如何鏈接OnUDPRead事件

Question

我無法將OnUDPRead事件鏈接到IdUDPServer。

代碼如下：

uses 
    System.SysUtils, IdUDPServer, IdGlobal, IdSocketHandle, Classes; 

var 
    udp: TIdUDPServer; 
    buffer: TIdBytes; 
    myBinding: TIdSocketHandle; 

procedure UDPRead (Sender: TObject; AData: TStream; ABinding: TIdSocketHandle); 
    var 
    bytes_received: integer; 
    begin 
    bytes_received:= AData.size; 
    end; 

begin 
    myBinding := udp.Bindings.Add; 
    myBinding.IP := '0.0.0.0'; 
    myBinding.Port := 5100; 

    udp.OnUDPRead := UDPRead; // Error occurs here 
    udp.Active := True; 
end. 

我收到錯誤消息：

[dcc32 Error] ACUR401_20170802_UDPServer.dpr(16): E2029 ';' expected but 'OF' found 
[dcc32 Error] ACUR401_20170802_UDPServer.dpr(28): E2009 Incompatible types: 'method pointer and regular procedure' 

我相信我的困難是，我無法將事件處理程序鏈接到程序。

Answer 1

您必須爲OnUDPRead屬性指定一個匹配的對象方法。你分配的是一個常規程序。做這樣的事情：

type 
    TMyObject = class 
    public 
    procedure UDPRead(AThread: TIdUDPListenerThread; AData: TIdBytes; 
     ABinding: TIdSocketHandle); 
    end; 

{ TMyObject } 

procedure TMyObject.UDPRead(AThread: TIdUDPListenerThread; AData: TIdBytes; 
    ABinding: TIdSocketHandle); 
var 
    Received: Integer; 
begin 
    Received := Length(AData); 
    ... 
end; 

var 
    MyObject: TMyObject; 
    MyServer: TIdUDPServer; 
    MyBinding: TIdSocketHandle; 
begin 
    MyServer := TIdUDPServer.Create(nil); 
    try 
    MyBinding := MyServer.Bindings.Add; 
    MyBinding.IP := '0.0.0.0'; 
    MyBinding.Port := 5100; 

    MyObject := TMyObject.Create; 
    try 
     MyServer.OnUDPRead := MyObject.UDPRead; 
     MyServer.Active := True; 
    finally 
     MyObject.Free; 
    end; 
    finally 
    MyServer.Free; 
    end; 
end.