Delphi的Indy10全接触之UDP篇.doc

Delphi2009的Indy全接触之UDP篇首先新建服务端。如下图所示建立工程：代码如下：unitServerUnit;interfaceusesWindows,Messages,SysUtils,Variants,Classes,Graphics,Controls,Forms,Dialogs,IdBaseComponent,IdComponent,IdUDPBase,IdUDPServer,StdCtrls,IdSocketHandle,IdGlobal;typeTServerForm=class(TForm)Label1:TLabel;Edit1:TEdit;Label2:TLabel;Edit2:TEdit;Label3:TLabel;Edit3:TEdit;IdUDPServer1:TIdUDPServer;procedureIdUDPServer1UDPRead(AThread:TIdUDPListenerThread;AData:TBytes;ABinding:TIdSocketHandle);procedureFormCreate(Sender:TObject);privatePrivatedeclarationspublicPublicdeclarationsend;varServerForm:TServerForm;implementation$R*.dfm/窗体创建部分procedureTServerForm.FormCreate(Sender:TObject);beginIdUDPServer1.DefaultPort:=3030;IdUDPServer1.Active:=True;Edit1.ReadOnly:=True;Edit2.ReadOnly:=True;Edit3.ReadOnly:=True;end;/数据接收部分procedureTServerForm.IdUDPServer1UDPRead(AThread:TIdUDPListenerThread;AData:TBytes;ABinding:TIdSocketHandle);beginEdit1.Text:=ABinding.PeerIP;Edit2.Text:=IntToStr(ABinding.PeERPort);Edit3.Text:=BytesToString(AData);IdUDPServer1.Send(ABinding.PeerIP,ABinding.PeerPort,TimeToStr(Time)+=Serverreceivedthemessage!);end;end.然后新建客户端如下图所示：注意：为了让客户端能实时监控服务端发回来的确定消息，使用了TTimer控件，Interval设置为250毫秒。代码如下：unitClientUnit;interfaceusesWindows,Messages,SysUtils,Variants,Classes,Graphics,Controls,Forms,Dialogs,StdCtrls,ExtCtrls,IdBaseComponent,IdComponent,IdUDPBase,IdUDPClient;typeTClientForm=class(TForm)Label1:TLabel;Edit1:TEdit;Button1:TButton;Label2:TLabel;Edit2:TEdit;IdUDPClient1:TIdUDPClient;Timer1:TTimer;procedureButton1Click(Sender:TObject);procedureFormCreate(Sender:TObject);procedureTimer1Timer(Sender:TObject);privatePrivatedeclarationspublicPublicdeclarationsend;varClientForm:TClientForm;implementation$R*.dfm/数据发送procedureTClientForm.Button1Click(Sender:TObject);beginIdUDPClient1.Broadcast(Edit1.Text,3030);Timer1.Enabled:=True;end;/窗体创建procedureTClientForm.FormCreate(Sender:TObject);beginTimer1.Enabled:=False;Edit2.ReadOnly:=True;end;/数据接收procedureTClientForm.Timer1Timer(Sender:TObject);beginEdit2.Text:=IdUDPClient1.ReceiveString(-1);Timer1.Enabled:=False;end;end.如此实现简单的UDP协议下局域网通讯。但是很快我又发现，上面的代码在本机虽然能够正常执行，分别位于2台电脑时会发生无法接收服务器响应的现象。究其原因可能是客户程序用户界面“冻结”的缘故。于是在服务端和客户端都加上TIdAntiFreeze以解决上面发生的现象(尤其是客户端)。服务端：客户端：事实上，上述客户端的TTimer控件是完全没有必要使用的。当我们对IdUDPClient使用Broadcast方法后，一旦与服务端通讯成功，IdUDPClient自动会得到来自服务端的返回值。如果通讯失败，在IdUDPClient.ReceiveTimeout所设定的事件后终止响应，所以我们可以吧延迟事件稍微设长一点。于是客户端代码可以简单的写成unitClientUnit;interfaceusesWindows,Messages,SysUtils,Variants,Classes,Graphics,Controls,Forms,Dialogs,StdCtrls,ExtCtrls,IdBaseComponent,IdComponent,IdUDPBase,IdUDPClient,IdAntiFreezeBase,IdAntiFreeze;typeTClientForm=class(TForm)Label1:TLabel;Edit1:TEdit;Button1:TButton;Label2:TLabel;Edit2:TEdit;IdUDPClient1:TIdUDPClient;IdAntiFreeze1:TIdAntiFreeze;procedureButton1Click(Sender:TObject);procedureFormCreate(Sender:TObject);privatePrivatedeclarationspublicPublicdeclarationsend;varClientForm:TClientForm;implementation$R*.dfm/数据发送procedureTClientForm.Button1Click(Sender:TObject);beginIdUDPClient1.Broadcast(Edit1.Text,3030);Edit2.Text:=IdUDPClient1.ReceiveString(-1);end;/窗体接收procedureTClientForm.FormCreate(Sender:TObject);beginIdUDPClient1.ReceiveTimeout:=5000;Edit2.ReadOnly:=True;end;end.如此即可完成与服务端的通讯。关于网络中查找服务器主机的问题，似乎可以使用UDP广播的方式查找。先看代码：unitClientUnit;interfaceusesWindows,Messages,SysUtils,Variants,Classes,Graphics,Controls,Forms,Dialogs,StdCtrls,ExtCtrls,IdBaseComponent,IdComponent,IdUDPBase,IdUDPClient,IdAntiFreezeBase,IdAntiFreeze;typeTClientForm=class(TForm)Label1:TLabel;Edit1:TEdit;Button1:TButton;Label2:TLabel;IdUDPClient1:TIdUDPClient;IdAntiFreeze1:TIdAntiFreeze;ListBox1:TListBox;Timer1:TTimer;procedureButton1Click(Sender:TObject);procedureFormCreate(Sender:TObject);procedureTimer1Timer(Sender:TObject);privatePrivatedeclarationsvarIpList:TStringList;publicPublicdeclarationsend;varClientForm:TClientForm;implementation$R*.dfmprocedureTClientForm.Button1Click(Sender:TObject);beginIdUDPClient1.Broadcast(Edit1.Text,3030);ListBox1.Items.Add(IdUDPClient1.ReceiveString();end;procedureTClientForm.FormCreate(Sender:TObject);beginIdUDPClient1.ReceiveTimeout:=10000;IpList:=TStringList.Create;end;procedureTClientForm.Timer1Timer(Sender:TObject);varipaddr:string;varI:Integer;beginIdUDPClient1.BroadcastEnabled:=True;IdUDPClient1.Broadcast(SearchHost,3030);ipaddr:=IdUDPClient1.ReceiveString();ifIpList.IndexOf(ipaddr)=-1thenIpList.Add(ipaddr);ListBox1.Cl