firedac数据集和字符串相互转换

最新推荐文章于 2023-02-27 09:39:25 发布

转载最新推荐文章于 2023-02-27 09:39:25 发布 · 175 阅读

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#数据库

本文介绍了一种使用FireDAC组件将数据库记录序列化为字符串的方法，包括加压、BASE64编码及从字符串中还原数据的过程。通过具体函数实现，展示了如何在Delphi中高效地处理数据库数据。

uses Data.FireDACJSONReflect

1）FIREDAC数据库序列为字符串，进行了加压和BASE64编码

function DataSetToString(const ADataSet: TFDAdaptedDataSet): string;
var
LBinary64: string;
LMemoryStream: TMemoryStream;
LStringStream: TStringStream;
LDstStream: TMemoryStream;
Zipper: TZCompressionStream;
begin
LDstStream := TMemoryStream.Create;
try
LMemoryStream := TMemoryStream.Create;
try
ADataSet.SaveToStream(LMemoryStream, TFDStorageFormat.sfBinary);
LMemoryStream.Seek(0, TSeekOrigin.soBeginning);
Zipper := TZCompressionStream.Create(clDefault, LDstStream);
try
Zipper.CopyFrom(LMemoryStream, LMemoryStream.Size);
finally
Zipper.Free;
end;
finally
LMemoryStream.Free;
end;
LDstStream.Seek(0, TSeekOrigin.soBeginning);

LStringStream := TStringStream.Create;
try
TNetEncoding.Base64.Encode(LDstStream, LStringStream);
LBinary64 := LStringStream.DataString;
finally
LStringStream.Free;
end;
finally
LDstStream.Free;
end;
Result := LBinary64;
end;

2）从字符串还原出来FDMEMTABLE，进行了解压和BASE64解码

function MemTableFromString(const AValue: string): TFDMemTable;
var
LMemTable: TFDMemTable;
LStringStream: TStringStream;
LMemoryStream: TMemoryStream;
LOrgStream: TMemoryStream;
Unzipper: TZDecompressionStream;
begin
LMemTable := TFDMemTable.Create(nil);
LMemoryStream := TMemoryStream.Create;
try
LStringStream := TStringStream.Create(AValue);
try
LOrgStream := TMemoryStream.Create;
try
TNetEncoding.Base64.Decode(LStringStream,LOrgStream);
LOrgStream.Seek(0, TSeekOrigin.soBeginning);
Unzipper := TZDecompressionStream.Create(LOrgStream);
try
LMemoryStream.CopyFrom(Unzipper, Unzipper.Size);
finally
Unzipper.Free;
end;
LMemoryStream.Seek(Longint(0), soFromBeginning);
finally
LOrgStream.Free;
end;
finally
LStringStream.Free;
end;
LMemTable.LoadFromStream(LMemoryStream, TFDStorageFormat.sfBinary);
finally
LMemoryStream.Free;
end;
Result := LMemTable;
end;