我在Delphi XE2中使用Indy使用TIdTCPServer发送TCP消息时遇到一个问题。
例如： 我有2台设备，我将与设备1进行通信。 当我向设备1发送消息时，消息被发送正常。 但是在没有关闭程序的情况下，当我向设备2发送消息时，Delphi返回＆＃34;连接由同行重置＆＃34;。
以下是我的代码：
procedure TMainHost.idTCPServerNewConnect(AContext: TIdContext);
var
Client: TSimpleClient;
begin
Sleep(1000);
Client := TSimpleClient.Create();
Client.DNS := AContext.Connection.Socket.Host;
Client.Conectado := True;
Client.Port := idTCPServerNew.DefaultPort;
Client.Name := 'Central';
Client.ListLink := Clients.Count;
Client.Thread := AContext;
Client.IP := AContext.Connection.Socket.Binding.PeerIP;
AContext.Data := Client;
Clients.Add(Client);
Sleep(500);
if (MainEstrutura.current_central.IP = Client.IP) then
begin
MainEstrutura.current_central.Conectado := true;
MainEstrutura.envia_configuracao;
end;
end;
procedure TMainHost.idTCPServerNewDisconnect(AContext: TIdContext);
var
Client: TSimpleClient;
begin
{ Retrieve Client Record from Data pointer }
Client := Pointer(AContext.Data);
{ Remove Client from the Clients TList }
Clients.Remove(Client);
{ Free the Client object }
FreeAndNil(Client);
AContext.Data := nil;
end;
将消息发送到设备：
procedure TMainHost.DirectTCPMessage(IP: String; TheMessage: String);
var
Client: TSimpleClient;
i: Integer;
List: TList;
Msg: String;
begin
Msg := Trim(TheMessage);
for i := 0 to Clients.Count - 1 do
begin
Client := TSimpleClient(Clients.Items[i]);
if TIdContext(Client.Thread).Connection.Socket.Binding.PeerIP = IP then
begin
TIdContext(Client.Thread).Connection.Socket.WriteLn(Msg);
end;
end;
end;
我有另一个问题。
当我在tidtcpserver组件上设置active：= False时，应用程序崩溃。 谢谢！
答案 0 :(得分：4)
您的Clients列表未受多线程访问保护。 TIdTCPServer是一个多线程组件，每个客户端都在自己的工作线程中运行。你需要考虑到这一点。我建议您完全删除Clients列表并使用TIdTCPServer.Contexts属性。否则，您需要保护Clients列表，例如将其更改为TThreadList，或者至少使用TCriticalSection（TThreadList内部Client.DNS包裹它）。
我看到的另一个问题是，您将Client.DNS字段设置为错误值，这可能会影响您的通信，具体取决于您使用procedure TMainHost.idTCPServerNewConnect(AContext: TIdContext);
var
Client: TSimpleClient;
begin
Client := TSimpleClient.Create();
Client.IP := AContext.Binding.PeerIP;
Client.DNS := GStack.HostByAddress(Client.IP, AContext.Binding.IPVersion);
Client.Conectado := True;
Client.Port := AContext.Binding.Port;
Client.Name := 'Central';
Client.Thread := AContext;
AContext.Data := Client;
// this may or may not need to be Synchronized, depending on what it actually does...
if (MainEstrutura.current_central.IP = Client.IP) then
begin
MainEstrutura.current_central.Conectado := true;
MainEstrutura.envia_configuracao;
end;
end;
procedure TMainHost.idTCPServerNewDisconnect(AContext: TIdContext);
var
Client: TSimpleClient;
begin
{ Retrieve Client Record from Data pointer }
Client := TSimpleClient(AContext.Data);
{ Free the Client object }
FreeAndNil(Client);
AContext.Data := nil;
end;
的内容。
请改为尝试：
procedure TMainHost.DirectTCPMessage(IP: String; TheMessage: String);
var
List: TIdContextList; // or TList in an earlier version that did not have TIdContextList yet
Context: TIdContext;
i: Integer;
Msg: String;
begin
Msg := Trim(TheMessage);
List := idTCPServerNew.Contexts.LockList;
try
for i := 0 to List.Count - 1 do
begin
Context := Context(List[i]);
if TSimpleClient(Context.Data).IP = IP then
begin
try
Context.Connection.IOHandler.WriteLn(Msg);
except
end;
Break;
end;
end;
finally
idTCPServerNew.Contexts.UnlockList;
end;
end;
OnExecute话虽如此，如果您的服务器从CommandsHandlers事件或OnExecute集合内部发送任何数据，那么这种从其线程外部向客户端发送消息的方法并不安全，如您冒着重叠数据的风险，这会破坏与该客户的通信。更安全的方法是对传出数据进行排队，让procedure TMainHost.idTCPServerNewConnect(AContext: TIdContext);
var
Client: TSimpleClient;
begin
Client := TSimpleClient.Create();
...
Client.Queue := TIdThreadSafeStringList.Create; // <-- add this
...
end;
procedure TMainHost.idTCPServerNewExecute(AContext: TIdContext);
var
List: TStringList;
I: Integer;
begin
Client := TSimpleClient(AContext.Data);
...
List := Client.Queue.Lock;
try
while List.Count > 0 do
begin
AContext.Connection.IOHandler.WriteLn(List[0]);
List.Delete(0);
end;
finally
Client.Queue.Unlock;
end;
...
end;
事件在安全的情况下发送数据，例如：
procedure TMainHost.DirectTCPMessage(IP: String; TheMessage: String);
var
List: TIdContextList; // or TList in an earlier version that did not have TIdContextList yet
Context: TIdContext;
i: Integer;
Msg: String;
begin
Msg := Trim(TheMessage);
List := idTCPServerNew.Contexts.LockList;
try
for i := 0 to List.Count - 1 do
begin
Context := Context(List[i]);
if TSimpleClient(Context.Data).IP = IP then
begin
TSimpleClient(Context.Data).Queue.Add(Msg);
Break;
end;
end;
finally
idTCPServerNew.Contexts.UnlockList;
end;
end;
TSimpleClient 更新：如果说，我建议从TIdServerContext派生ContextsClass并将其分配给服务器的TIdContext.Data属性，那么您不需要再次使用type
TSimpleClient = class(TIdServerContext)
public
Queue: TIdThreadSafeStringList;
...
// or TThreadList in an earlier version that did not have TIdContextThreadList yet
constructor Create(AConnection: TIdTCPConnection; AYarn: TIdYarn; AList: TIdContextThreadList = nil); override;
destructor Destroy; override;
end;
constructor TSimpleClient.Create(AConnection: TIdTCPConnection; AYarn: TIdYarn; AList: TIdContextThreadList = nil);
begin
inherited;
Queue := TIdThreadSafeStringList.Create;
...
end;
destructor TSimpleClient.Destroy;
begin
...
Queue.Free;
inherited;
end;
procedure TMainHost.FormCreate(Sener: TObject);
begin
// this must be assigned before the server is activated
idTCPServerNew.ContextClass := TSimpleClient;
end;
procedure TMainHost.idTCPServerNewConnect(AContext: TIdContext);
var
Client: TSimpleClient;
...
begin
Client := AContext as TSimpleClient;
// use Client as needed...
end;
procedure TMainHost.idTCPServerNewExecute(AContext: TIdContext);
var
Client: TSimpleClient;
...
begin
Client := AContext as TSimpleClient;
// use Client as needed...
end;
procedure TMainHost.DirectTCPMessage(IP: String; TheMessage: String);
var
List: TIdContextList; // or TList in an earlier version that did not have TIdContextList yet
Client: TSimpleClient;
i: Integer;
Msg: String;
begin
Msg := Trim(TheMessage);
List := idTCPServerNew.Contexts.LockList;
try
for i := 0 to List.Count - 1 do
begin
Client := TIdContext(Context(List[i])) as TSimpleClient;
if Client.IP = IP then
begin
Client.Queue.Add(Msg);
Break;
end;
end;
finally
idTCPServerNew.Contexts.UnlockList;
end;
end;
属性：
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