Delphi盒子-问答悬赏

疯狂的狼：  SAFEARRAY的主要目的是用于automation中的数组型参数的传递。因为在网络环境中，数组是不能直接传递的，而必须将其包装成SafeArray。实质上SafeArray就是将通常的数组增加一个描述符，说明其维数、长度、边界、元 素类型等信息。SafeArray也并不单独使用，而是将其再包装到VARIANT类型的变量中，然后才作为参数传送出去。在VARIANT的vt成员的 值如果包含VT_ARRAY|...,那么它所封装的就是一个SafeArray，它的parray成员即是指向SafeArray的指针。 SafeArray中元素的类型可以是VARIANT能封装的任何类型，包括VARIANT类型本身。
Delphi中com组件或外部调用需要传递一个对象或者数组，这个时候可以考虑使用SafeArray。比如三层架构中通常需要将使用的ClientDataSet数据集传出，那么就可以将DataSet转换为SafeArray，再由其他模块转换接收。

===============================================================================
代码块：

pSafeArray是一个结构体，其定义在ActiveX单元中，相关定义如下：
PSafeArray = ^TSafeArray;

{$EXTERNALSYM tagSAFEARRAY}

tagSAFEARRAY = record

    cDims: Word;//数组的维数

    fFeatures: Word;//用来描述数组如何分配和如何被释放的标志

    cbElements: Longint;//数组元素的大小

    cLocks: Longint;//一个计数器，用来跟踪该数组被锁定的次数

    pvData: Pointer;//指向数据缓冲的指针

    rgsabound: array[0..0] of TSafeArrayBound;//描述数组每维的数组结构，该数组的大小是可变的

end;

TSafeArray = tagSAFEARRAY;

{$EXTERNALSYM SAFEARRAY}

SAFEARRAY = TSafeArray;

===============================================================================

一维数组的传递：

//一维数组传递

procedure TForm1.ArrayToSafeArray(DataArray: array of string);

var

VarBound: TVarArrayBound;

psa: PSafeArray;

i: Integer;

AV1: OleVariant;

begin

//初始化OleValue

VariantInit(OleValue);

VarBound.LowBound := 0;

VarBound.ElementCount := High(DataArray) + 1;
psa := SafeArrayCreate(VT_BSTR, 1, VarBound);//创建SafeArray对象

//将数组元素放到SafeArray中

for i := Low(DataArray) to High(DataArray) do

begin

    AV1 := DataArray[i];

    SafeArrayPutElement(psa, i, TVarData(AV1).VPointer^);

end;

//封装到Varaint变量中

TVarData(OleValue).VType := VT_ARRAY or VT_BSTR;

TVarData(OleValue).VArray := pVarArray(psa);

end;
读取一维safeArray的步骤：

//使用SafeArrayGetLBound、SafeArrayGetUBound方法获取safeArray数组上下限

function TForm1.SafeArrayToText(OleValue: OleVariant): string;

var

RVarData: TVarData;

RBound: TVarArrayBound;

j, UCount: Integer;

aValue: WideString;

begin

Result := '';

//获取OleVaraint对象指针

RVarData := FindVarData(OleValue)^;

if RVarData.VArray = nil then

    Exit;

VarResultCheck((SafeArrayGetLBound(pSafeArray(RVarData.VArray), 1, RBound.LowBound)));

VarResultCheck(SafeArrayGetUBound(pSafearray(RVarData.VArray), 1, UCount));

RBound.ElementCount := UCount - RBound.LowBound;

for j := RBound.LowBound to RBound.ElementCount do

begin

    VarResultCheck(SafeArrayGetElement(PSafeArray(RVarData.VArray), j, aValue));

    if Result = '' then

      Result := Result + aValue

    else

      Result := Result + ',' + aValue;

end;

end;
//另外附上将DataSet通过SafeArray传递的方法,其实为多维数组的传递:

procedure TForm1.DataSetToSafeArray(ClientData: TClientDataSet);

var

DataArray: TDoubleArray;

VarBound: array[0..1] of TVarArrayBound;

Demen: array[0..1] of DWORD;

psa: PSafeArray;

i, j, k, Count: Integer;

AV1: OleVariant;

begin

SetLength(DataArray, ClientData.FieldCount + 1, ClientData.RecordCount + 1);

Count := 0;

ClientData.First;

while not ClientData.Eof do

begin

    for i := 0 to ClientData.FieldCount - 1 do

    begin

      if Count = 0 then

        DataArray[i][Count] := ClientData.Fields[i].FieldName

      else

        DataArray[i][Count] := ClientData.Fields[i].Value;

    end;

    if Count > 0 then

      ClientData.Next;

    inc(Count);

end;

//--------开始转换为SafeArray-----------

//初始化OleValue

VariantInit(OleValue);

VarBound[0].LowBound := 0;

VarBound[0].ElementCount := ClientData.FieldCount + 1;

VarBound[1].LowBound := 0;

VarBound[1].ElementCount := ClientData.RecordCount + 1;
psa := SafeArrayCreate(VT_BSTR, 2, VarBound);

for i := Low(DataArray) to High(DataArray) do

begin

    Demen[0] := i;

    for j := Low(DataArray[i]) to High(DataArray[i]) do

    begin

      Demen[1] := j;

      AV1 := DataArray[i][j];

      SafeArrayPutElement(psa, Demen, TVarData(AV1).VPointer^);

    end;

end;
TVarData(OleValue).VType := VT_ARRAY or VT_BSTR;

TVarData(OleValue).VArray := pVarArray(psa);

end;
//读多维数组，读出后再转换为想要的格式：

function TForm1.SafeArrayToDataSet(oleValue: OleVariant): string;

var

RVarData: TVarData;

RBound: array[0..1] of TVarArrayBound;

Demen: array[0..1] of DWORD;

i, j, DCount, UCount, iCount: Integer;

aValue: WideString;

begin

Result := '';

RVarData := FindVarData(OleValue)^;

if RVarData.VArray = nil then

    Exit;

DCount := RVarData.Varray^.DimCount; //取维数

for i := 0 to DCount - 1 do

begin

    VarResultCheck((SafeArrayGetLBound(pSafeArray(RVarData.VArray), i + 1, RBound[i].LowBound)));

    VarResultCheck(SafeArrayGetUBound(pSafearray(RVarData.VArray), i + 1, UCount));

    RBound[i].ElementCount := UCount - RBound[i].LowBound;

end;

for j := RBound[1].LowBound to RBound[1].ElementCount do

begin

    Demen[1] := j;

    for iCount := RBound[0].LowBound to RBound[0].ElementCount do

    begin

      Demen[0] := iCount;

      VarResultCheck(SafeArrayGetElement(PSafeArray(RVarData.VArray), demen, aValue));

      if Result = '' then

        Result := Result + aValue

      else

        Result := Result + ',' + aValue;

    end;

end;

end;
 
希望对你有点作用！