delphi问题集锦（6问）

1、判断机器是否网络状态
答：
uses WinInet;
procedure TForm1.Button1Click(Sender: TObject);
function GetOnlineStatus : Boolean;
var ConTypes : Integer;
begin
ConTypes := INTERNET_CONNECTION_MODEM + INTERNET_CONNECTION_LAN + INTERNET_CONNECTION_PROXY;
if (InternetGetConnectedState(@ConTypes, 0) = False)
then Result := False
else Result := True;
end;
begin
if not GetOnlineStatus then ShowMessage(''Not Connected'');
end;

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2、[DELPHI]窗体渐渐出现
答：
AnimateWindow(Handle,1000,AW_CENTER);
//在窗体创建事件中

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3、如何取得一台机器的CPU占用率　？
答：
使用下面的方法
interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

const
SystemBasicInformation = 0;
SystemPerformanceInformation = 2;
SystemTimeInformation = 3;

type
TPDWord = ^DWORD;

TSystem_Basic_Information = packed record
dwUnknown1: DWORD;
uKeMaximumIncrement: ULONG;
uPageSize: ULONG;
uMmNumberOfPhysicalPages: ULONG;
uMmLowestPhysicalPage: ULONG;
uMmHighestPhysicalPage: ULONG;
uAllocationGranularity: ULONG;
pLowestUserAddress: Pointer;
pMmHighestUserAddress: Pointer;
uKeActiveProcessors: ULONG;
bKeNumberProcessors: byte;
bUnknown2: byte;
wUnknown3: word;
end;

type
TSystem_Performance_Information = packed record
liIdleTime: LARGE_INTEGER; {LARGE_INTEGER}
dwSpare: array[0..75] of DWORD;
end;

type
TSystem_Time_Information = packed record
liKeBootTime: LARGE_INTEGER;
liKeSystemTime: LARGE_INTEGER;
liExpTimeZoneBias: LARGE_INTEGER;
uCurrentTimeZoneId: ULONG;
dwReserved: DWORD;
end;

var
NtQuerySystemInformation: function(infoClass: DWORD;
buffer: Pointer;
bufSize: DWORD;
returnSize: TPDword): DWORD; stdcall = nil;


liOldIdleTime: LARGE_INTEGER = ();
liOldSystemTime: LARGE_INTEGER = ();
SysBaseInfo: TSystem_Basic_Information;
SysPerfInfo: TSystem_Performance_Information;
SysTimeInfo: TSystem_Time_Information;
status: Longint; {long}
dbSystemTime: Double;
dbIdleTime: Double;
function GetCPUUsage:Double;
implementation
function Li2Double(x: LARGE_INTEGER): Double;
begin
Result := x.HighPart * 4.294967296E9 + x.LowPart
end;

function GetCPUUsage:Double;
var
bLoopAborted : boolean;
begin
if @NtQuerySystemInformation = nil then
NtQuerySystemInformation := GetProcAddress(GetModuleHandle(‘ntdll.dll‘),
‘NtQuerySystemInformation‘);
// get number of processors in the system
status := NtQuerySystemInformation(SystemBasicInformation, @SysBaseInfo, SizeOf(SysBaseInfo), nil);
if status <> 0 then Exit;
// Show some information
{with SysBaseInfo do
begin
ShowMessage(
Format(‘uKeMaximumIncrement: %d‘#13‘uPageSize: %d‘#13+
‘uMmNumberOfPhysicalPages: %d‘+#13+‘uMmLowestPhysicalPage: %d‘+#13+
‘uMmHighestPhysicalPage: %d‘+#13+‘uAllocationGranularity: %d‘#13+
‘uKeActiveProcessors: %d‘#13‘bKeNumberProcessors: %d‘,
[uKeMaximumIncrement, uPageSize, uMmNumberOfPhysicalPages,
uMmLowestPhysicalPage, uMmHighestPhysicalPage, uAllocationGranularity,
uKeActiveProcessors, bKeNumberProcessors]));
end;
}
bLoopAborted := False;
while not bLoopAborted do
begin
// get new system time
status := NtQuerySystemInformation(SystemTimeInformation, @SysTimeInfo, SizeOf(SysTimeInfo), 0);
if status <> 0 then Exit;
// get new CPU‘s idle time
status := NtQuerySystemInformation(SystemPerformanceInformation, @SysPerfInfo, SizeOf(SysPerfInfo), nil);
if status <> 0 then Exit;
// if it‘s a first call - skip it
if (liOldIdleTime.QuadPart <> 0) then
begin
// CurrentValue = NewValue - OldValue
dbIdleTime := Li2Double(SysPerfInfo.liIdleTime) - Li2Double(liOldIdleTime);
dbSystemTime := Li2Double(SysTimeInfo.liKeSystemTime) - Li2Double(liOldSystemTime);
// CurrentCpuIdle = IdleTime / SystemTime
dbIdleTime := dbIdleTime / dbSystemTime;
// CurrentCpuUsage% = 100 - (CurrentCpuIdle * 100) / NumberOfProcessors
dbIdleTime := 100.0 - dbIdleTime * 100.0 / SysBaseInfo.bKeNumberProcessors + 0.5;
// Show Percentage
//Form1.Label1.Caption := FormatFloat(‘CPU Usage: 0.0 %‘,dbIdleTime);
//Application.ProcessMessages;
// Abort if user pressed ESC or Application is terminated
Result:=dbIdleTime;
bLoopAborted:=True;
//bLoopAborted := (GetKeyState(VK_ESCAPE) and 128 = 128) or Application.Terminated;
end;
// store new CPU‘s idle and
　

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4、动态生成控件？
答：
var
TeSpeedButtonX:TTeSpeedButton;
begin
TeSpeedButtonX:=TTeSpeedButton.Create(nil);
TeSpeedButtonX.Caption:=''标题'';
TeSpeedButtonX.Name:=''按钮''+inttostr(X);
TeSpeedButtonX.Parent:=Tetoolbar2;
X:=X+1;
end;
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5、我动态创建了多个button，使用时，我怎么判断出用户点击的是哪个button呢？button的各项属性都边成最后创建的那个button的了，怎么办哦？
答1：
教你一招,先设置每个button的tag属性.然后在onclick事件中用(sender as button).tag来判断,相信我,没错的!

答2：
如果你生成的控件不是很多的话，最简单的方法就是，假如你生成控件的父控件是FORM1，利用循环判断控件是否等于FORM1.ACTIVECONTROL，我就是这么用的。ACTIVECONTROL就是记录当前被点击的控件，你也可以直接用它，不过直接只能用到CONTROL的一般属性和方法，循环判断的话就可以用到你生成控件的相关属性。

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6、窗体释放问题
答：
在Form2.OnClose事件中
Action:=caFree;