自动检查网络连接状况，如果异常自动重连

{author:cxg断网自动检查并提示，自动重连}

unit ClientTestConnected;

interface

uses  SysUtils, Classes, SqlExpr,uNetCommon;

type  TWaitThread = class(TThread)  private    { Private declarations }    fNetConnect:Boolean;    FCheckInterval: Integer;    FMsg: string;  protected    procedure ShowMsg;    procedure Execute; override;    procedure ServerOpen;    procedure ServerClose;    function ConnRemoteSvr(cn:TSQLConnection;const hostname,UserName,password:string;      const port:Integer):Boolean;  public    NetCheck1: TNetCheck;    constructor Create(const ACheckInterval: Integer);    destructor Destroy; override;

    procedure CheckNetConnect(Sender: TObject; var objWbemObject,      objWbemAsyncContext: OleVariant);    procedure CheckNetDisconnect(Sender: TObject; var objWbemObject,      objWbemAsyncContext: OleVariant);  end;

implementation

uses ClientForm;

procedure TWaitThread.ServerClose;begin  FrmMain.SQLConnection1.Close;end;

procedure TWaitThread.ServerOpen;begin  if fNetConnect then  FMsg := '正在连接...'  else FMsg :='网络异常';  Synchronize(ShowMsg);  if ConnRemoteSvr(FrmMain.SQLConnection1,'localhost','cxg','123',211) then  begin    FMsg := '网络正常';    Synchronize(ShowMsg);  end;end;

procedure TWaitThread.ShowMsg;begin  FrmMain.Label1.Caption := FMsg;end;

procedure TWaitThread.Execute;begin  try    ServerOpen;    fNetConnect :=True;  except    fNetConnect :=False;  end;

  repeat    Sleep(FCheckInterval);    if not fNetConnect then    begin      FCheckInterval := 3000;      ServerClose;      ServerOpen;    end;  until Terminated;end;

procedure TWaitThread.CheckNetConnect(Sender: TObject; var objWbemObject,  objWbemAsyncContext: OleVariant);begin  fNetConnect := True;end;

procedure TWaitThread.CheckNetDisconnect(Sender: TObject; var objWbemObject,  objWbemAsyncContext: OleVariant);begin  fNetConnect :=False;end;

function TWaitThread.ConnRemoteSvr(cn: TSQLConnection; const hostname, UserName,  password: string; const port: Integer): Boolean;begin  try  cn.Close;  cn.DriverName := 'DataSnap';  cn.LoginPrompt :=False;  Cn.ConnectionName := 'DataSnapCONNECTION';  cn.Params.Clear;  cn.Params.Add('DriverName=DataSnap');  Cn.Params.Add('HostName='+HostName);  Cn.Params.Add('Port='+inttostr(port));  Cn.Params.Add('User_Name='+UserName);  Cn.Params.Add('Password='+PassWord);  cn.Open;  Result :=True;  except    Result :=False;  end;end;

constructor TWaitThread.Create(const ACheckInterval: Integer);begin  FCheckInterval := ACheckInterval;  NetCheck1 :=TNetCheck.Create(nil);  NetCheck1.OnNetWireConnect:=CheckNetConnect;  NetCheck1.OnNetWireDisconnect:=CheckNetDisconnect;  inherited Create(False);end;

destructor TWaitThread.Destroy;begin  NetCheck1.Free;  NetCheck1 :=nil;  inherited;end;

end.