TDSTCPServerTransport 的Filters

TDSTCPServerTransport 的Filters

TDSTCPServerTransport 的 Filter 属性，可以对传递的数据进行加密，压缩，再修改等，有
点注入的概念。默认情况下，Datasnap 自带的ZLIB, PC1，RSA 三个Filter。测试了一下，
RSA 只对KEY 加密，PC1 才对内容加密，ZLIB 来做压缩，ZLIB 压缩实在不咋的。并且，
Filter 的顺序，是依次执行的。我现在打算实现，服务器的一个Log 功能，记录下来进入的
数据，出去的数据，要求记录下来的数据是明文。
TTransportFilter 的 ProcessInput ，ProcessOutput 光看名字比较费解，可以这么理解
ProcessInput 为编码，ProcessOutput 可以理解为解码。

首先给DSTCPServerTransport1 的Fitlers 都加上默认的3 个Filter。
上一个完整的代码
unituLogFilter;

interface

uses
SysUtils, DBXPlatform, DBXTransport;

type
TLogHeadFilter =class(TTransportFilter)
public
constructorCreate;override;
destructorDestroy;override;
functionProcessInput(constData: TBytes): TBytes;override;
functionProcessOutput(constData: TBytes): TBytes;override;//do nothing
functionId: UnicodeString;override;
end;

TLogTailFilter =class(TTransportFilter)
public
constructorCreate;override;
destructorDestroy;override;
functionProcessInput(constData: TBytes): TBytes;override;//do nothing
functionProcessOutput(constData: TBytes): TBytes;override;
functionId: UnicodeString;override;
end;

procedureAddLogFilter(Filters: TTransportFilterCollection);

implementation

uses
CodeSiteLogging;

const
LogFilterName_Tail ='LogTail';
LogFilterName_Head ='LogHead';

procedureAddLogFilter(Filters: TTransportFilterCollection);
var
fs: TDBXStringArray;
i:Integer;
begin

fs := Filters.FilterIdList;
Filters.Clear;
Filters.AddFilter(LogFilterName_Head);
fori := Low(fs)toHigh(fs)do
begin
Filters.AddFilter(fs[i]);
end;
Filters.AddFilter(LogFilterName_Tail);
end;

constructorTLogTailFilter.Create;
begin
inheritedCreate;
//CodeSite.Send(csmBlue, 'TLogTailFilter.Create');
end;

destructorTLogTailFilter.Destroy;
begin
//CodeSite.Send(csmBlue, 'TLogTailFilter.Destroy');
inheritedDestroy;
end;

functionTLogTailFilter.ProcessInput(constData: TBytes): TBytes;
begin
Result := Data;
CodeSite.Send(csmOrange,'To Client: '+ IntToStr(Length(Data)));
end;

functionTLogTailFilter.ProcessOutput(constData: TBytes): TBytes;
begin
Result := Data;
CodeSite.Send(csmOrange,'From Client: '+ IntToStr(Length(Data)),
TEncoding.ASCII.GetString(Data));
end;

functionTLogTailFilter.Id: UnicodeString;
begin
Result := LogFilterName_Tail;
end;

{ TLogInputFilter }

constructorTLogHeadFilter.Create;
begin

inherited;
//CodeSite.Send(csmBlue, 'TLogHeadFilter.Create');
end;

destructorTLogHeadFilter.Destroy;
begin
//CodeSite.Send(csmBlue, 'TLogHeadFilter.Destroy');
inherited;
end;

functionTLogHeadFilter.Id: UnicodeString;
begin
Result := LogFilterName_Head;
end;

functionTLogHeadFilter.ProcessInput(constData: TBytes): TBytes;
begin
Result := Data;
CodeSite.Send(csmYellow,'To Client: '+ IntToStr(Length(Data)),
TEncoding.ASCII.GetString(Data));
end;

functionTLogHeadFilter.ProcessOutput(constData: TBytes): TBytes;
begin
Result := Data;
CodeSite.Send(csmYellow,'From Client: '+ IntToStr(Length(Data)));