delphi Zlib 流压缩解压

procedure UnCompressionStream(var ASrcStream:TMemoryStream); //解压缩
var
nTmpStream:TDecompressionStream;
nDestStream:TMemoryStream;
nBuf: array[1..512] of Byte;
nSrcCount: integer;
begin
ASrcStream.Position := 0;
nDestStream := TMemoryStream.Create;
nTmpStream := TDecompressionStream.Create(ASrcStream);
try
repeat
//读入实际大小
nSrcCount := nTmpStream.Read(nBuf, SizeOf(nBuf));
if nSrcCount > 0 then
nDestStream.Write(nBuf, nSrcCount);
until (nSrcCount = 0);
ASrcStream.Clear;
ASrcStream.LoadFromStream(nDestStream);
ASrcStream.Position := 0;
finally
nDestStream.Clear;
nDestStream.Free;
nTmpStream.Free;
end;
end;
procedure CompressionStream(var ASrcStream:TMemoryStream;ACompressionLevel:Integer = 2); //压缩流
var
nDestStream:TMemoryStream;
nTmpStream:TCompressionStream;
nCompressionLevel:TCompressionLevel;
begin
ASrcStream.Position := 0;
nDestStream := TMemoryStream.Create;
try
//级别
case ACompressionLevel of
0:nCompressionLevel := clNone;
1:nCompressionLevel := clFastest;
2:nCompressionLevel := clDefault;
3:nCompressionLevel := clMax;
else
nCompressionLevel := clMax;
end;
//开始压缩
nTmpStream := TCompressionStream.Create(nCompressionLevel,nDestStream);
try
ASrcStream.SaveToStream(nTmpStream);
finally
nTmpStream.Free;//释放后nDestStream才会有数据
end;
ASrcStream.Clear;
ASrcStream.LoadFromStream(nDestStream);
ASrcStream.Position := 0;
finally
nDestStream.Clear;
nDestStream.Free;
end;
end;