需要做一个APP控制设备的程序，思来想去放弃自己实现服务端，准备直接采用现成的MQTT服务端程序，自己只需要关心逻辑，传输的交个MQTT .网上能找到的delphi的版本是老外的基于一个三方网络库的，win32下面可以编译运行，需要修改部分AnsiString和WideString。测试的时候会掉线，此条可能是因为当时没细读协议，规定时间未发送心跳包，被服务端断开。改成 Android 死活没能编译通过，技术问题，遂放弃。准备自己读协议，重新用TIdTCPClient实现一遍，这样可以方便的跨平台，也无三方控件，同时深入理解一下mqtt.代码基本参考老外的版本。先弄个能用的测试代码出来。服务端使用mosquitto.客户端现已完成MQTT连接，MQTT心跳包。
unit uMain;
interface
uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,IdGlobal,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.StdCtrls, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, FMX.Layouts, FMX.Memo, FMX.Controls.Presentation, FMX.Edit;
const
FClientID='tndsoft'; //客户端ID,需要唯一，最终由设备ID代替
type
// Message type. 4 Bit unsigned.
TMQTTMessageType = (
Reserved0, //0 Reserved
CONNECT, // 1 Client request to connect to Broker
CONNACK, // 2 Connect Acknowledgment
PUBLISH, // 3 Publish message
PUBACK, // 4 Publish Acknowledgment
PUBREC, // 5 Publish Received (assured delivery part 1)
PUBREL, // 6 Publish Release (assured delivery part 2)
PUBCOMP, // 7 Publish Complete (assured delivery part 3)
SUBSCRIBE, // 8 Client Subscribe request
SUBACK, // 9 Subscribe Acknowledgment
UNSUBSCRIBE, // 10 Client Unsubscribe request
UNSUBACK, // 11 Unsubscribe Acknowledgment
PINGREQ, // 12 PING Request
PINGRESP, // 13 PING Response
DISCONNECT, // 14 Client is Disconnecting
Reserved15 // 15
);
TRemainingLength = Array of Byte; //剩余长度字段，可变，1到4字节
TUTF8Text = Array of Byte;
type
TMQTTMessage = Record
FixedHeader: Byte;
RL: TBytes;
Data: TBytes;
End;
{事件}
TConnAckEvent = procedure (Sender: TObject; ReturnCode: integer) of object;
type
TfMQTTForDelphi = class(TForm)
Memo1: TMemo;
IdTCPClient1: TIdTCPClient;
Button1: TButton;
Button2: TButton;
edtHost: TEdit;
edtPort: TEdit;
Button3: TButton;
Button4: TButton;
procedure IdTCPClient1Connected(Sender: TObject);
procedure IdTCPClient1Disconnected(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
type
TClientHandleThread=class(TThread)
private
{ Private declarations }
servercmd:integer;
serverMsg:string;
FCurrentData: TMQTTMessage;
FConnAckEvent: TConnAckEvent;//连接返回事件
procedure HandleInput;
protected
procedure Execute; override;
public
property OnConnAck : TConnAckEvent read FConnAckEvent write FConnAckEvent;
end;
var
fMQTTForDelphi: TfMQTTForDelphi;
myClientHandleThread:TClientHandleThread;
function FixedHeader(MessageType: TMQTTMessageType; Dup, Qos,Retain: Word): Byte;
function VariableHeader_Connect(KeepAlive: Word): TBytes;
procedure CopyIntoArray(var DestArray: Array of Byte; SourceArray: Array of Byte; StartIndex: integer);
function StrToBytes(str: string; perpendLength: boolean): TUTF8Text;
procedure AppendArray(var Dest: TUTF8Text; Source: Array of Byte);
function RemainingLength(x: Integer): TRemainingLength;
function BuildCommand(FixedHeader: Byte; RemainL: TRemainingLength; VariableHead: TBytes; Payload: Array of Byte): TBytes;
procedure AppendBytes(var DestArray: TBytes;const NewBytes: TBytes);
function RemainingLengthToInt(RLBytes: TBytes): Integer;
implementation
{$R *.fmx}
{$R *.NmXhdpiPh.fmx ANDROID}
{$R *.XLgXhdpiTb.fmx ANDROID}
{$R *.SmXhdpiPh.fmx ANDROID}
procedure TClientHandleThread.Execute;
var
CurrentMessage:TMQTTMessage;
vBuffer:TIdBytes;
Buffer: TBytes;
RLInt: Integer;
I:Integer;
begin
while not Terminated do
begin
if not fMQTTForDelphi.IdTCPClient1.Connected then
Terminate
else
try
CurrentMessage.FixedHeader := 0;
CurrentMessage.RL := nil;
CurrentMessage.Data := nil;
CurrentMessage.FixedHeader:=fMQTTForDelphi.IdTCPClient1.IOHandler.ReadByte; //读取FixedHdader
{读取剩余长度-编码过}
SetLength(CurrentMessage.RL,1);
SetLength(Buffer,1);
CurrentMessage.RL[0]:=fMQTTForDelphi.IdTCPClient1.IOHandler.ReadByte; //读取剩余长度第一位
for i := 1 to 3 do //读取剩余长度其他位数，剩余长度为可变长度1-4.
begin
if (( CurrentMessage.RL[i - 1] and 128) <> 0) then
begin
Buffer[0] := fMQTTForDelphi.IdTCPClient1.IOHandler.ReadByte;
AppendBytes(CurrentMessage.RL, Buffer);
end
else
Break;
end;
{解码剩余长度}
RLInt := RemainingLengthToInt(CurrentMessage.RL);
{将剩余长度的数据全部读出}
if (RLInt > 0) then
begin
SetLength(CurrentMessage.Data, RLInt);
fMQTTForDelphi.IdTCPClient1.IOHandler.ReadBytes(vBuffer,RLInt,True);
CurrentMessage.Data:=TBytes(vBuffer);
// FPSocket^.RecvBufferEx(Pointer(CurrentMessage.Data), RLInt, 1000);
end;
FCurrentData := CurrentMessage;
Synchronize(HandleInput);
except
end;
try
servercmd:=fMQTTForDelphi.IdTCPClient1.IOHandler.ReadWord;
Synchronize(HandleInput);
except
end;
end;
end;
procedure TClientHandleThread.HandleInput;
var
MessageType: Byte;
DataLen: integer;
QoS: integer;
sErrCode:string;
Topic: string;
Payload: string;
ResponseVH: TBytes;
ConnectReturn: Integer;
begin
if (FCurrentData.FixedHeader <> 0) then
begin
MessageType := FCurrentData.FixedHeader shr 4;
if (MessageType = Ord(CONNACK)) then
begin
// Check if we were given a Connect Return Code.
ConnectReturn := 0;
// Any return code except 0 is an Error
if ((Length(FCurrentData.Data) > 0) and (Length(FCurrentData.Data) < 4)) then
begin
ConnectReturn := FCurrentData.Data[1];
case ConnectReturn of
0:sErrCode:='连接已接受';
1:sErrCode:='连接已拒绝，不支持的协议版本';
2:sErrCode:='连接已拒绝，不合格的客户端标识符';
3:sErrCode:='连接已拒绝，服务端不可用';
4:sErrCode:='连接已拒绝，无效的用户名或密码';
5:sErrCode:='连接已拒绝，未授权';
end;
fMQTTForDelphi.Memo1.Lines.Add(sErrCode);
end;
//if Assigned(OnConnAck) then OnConnAck(Self, ConnectReturn);
end
else
if (MessageType = Ord(PUBLISH)) then
begin
// // Read the Length Bytes
// DataLen := BytesToStrLength(Copy(FCurrentData.Data, 0, 2));
// // Get the Topic
// SetString(Topic, PAnsiChar(@FCurrentData.Data[2]), DataLen);
// // Get the Payload
// SetString(Payload, PAnsiChar(@FCurrentData.Data[2 + DataLen]), (Length(FCurrentData.Data) - 2 - DataLen));
// if Assigned(OnPublish) then OnPublish(Self, Topic, Payload);
end
else
if (MessageType = Ord(SUBACK)) then
begin
// // Reading the Message ID
// ResponseVH := Copy(FCurrentData.Data, 0, 2);
// DataLen := BytesToStrLength(ResponseVH);
// // Next Read the Granted QoS
// QoS := 0;
// if (Length(FCurrentData.Data) - 2) > 0 then
// begin
// ResponseVH := Copy(FCurrentData.Data, 2, 1);
// QoS := ResponseVH[0];
// end;
// if Assigned(OnSubAck) then OnSubAck(Self, DataLen, QoS);
end
else
if (MessageType = Ord(UNSUBACK)) then
begin
// // Read the Message ID for the event handler
// ResponseVH := Copy(FCurrentData.Data, 0, 2);
// DataLen := BytesToStrLength(ResponseVH);
// if Assigned(OnUnSubAck) then OnUnSubAck(Self, DataLen);
end
else
if (MessageType = Ord(PINGRESP)) then
begin
fMQTTForDelphi.Memo1.Lines.Add('收到心跳应答包。');
// if Assigned(OnPingResp) then OnPingResp(Self);
end;
end;
end;
procedure TfMQTTForDelphi.Button1Click(Sender: TObject);
begin
IdTCPClient1.Host:=edtHost.Text;
IdTCPClient1.Port:=StrToInt(edtPort.Text);
IdTCPClient1.Connect;
end;
procedure TfMQTTForDelphi.Button2Click(Sender: TObject);
begin
myClientHandleThread:=TClientHandleThread.Create();
myClientHandleThread.Resume;
end;
procedure TfMQTTForDelphi.Button3Click(Sender: TObject);
var
MqttData_FixedHead:Byte; //固定头
MqttData_VariableHeader:TBytes;//可变头
MqttData_RemainingLength: TRemainingLength;//剩余长度
Payload: TUTF8Text;
SendData: TBytes; //构件完成的最终需要发送的二进制数据
begin
MqttData_FixedHead:=FixedHeader(CONNECT,0,0,0);
MqttData_VariableHeader:= VariableHeader_Connect(40);//构建可变头。参数单位秒，在此时间之内，客户端需要发送 PINGREQ 否则服务端将断开网络连接
{开始构建有效荷载，由于需要认证帐号密码，此处荷载内容为ID,USER,PWD}
SetLength(Payload, 0);
AppendArray(Payload, StrToBytes(FClientID, true)); //id
AppendArray(Payload, StrToBytes('ade', true)); //user
AppendArray(Payload, StrToBytes('ade', true)); //pwd
{计算剩余长度}
MqttData_RemainingLength:=RemainingLength(Length(MqttData_VariableHeader) + Length(Payload));
{组包}
SendData:=BuildCommand(MqttData_FixedHead, MqttData_RemainingLength, MqttData_VariableHeader, Payload);
{发送}
IdTCPClient1.Socket.Write(TIdBytes(SendData));
end;
procedure TfMQTTForDelphi.Button4Click(Sender: TObject);
var
FH: Byte;
RL: Byte;
Data: TBytes;
begin
SetLength(Data, 2);
FH := FixedHeader(PINGREQ, 0, 0, 0);
RL := 0;
Data[0] := FH;
Data[1] := RL;
IdTCPClient1.Socket.Write(TIdBytes(Data));
end;
procedure TfMQTTForDelphi.IdTCPClient1Connected(Sender: TObject);
begin
Memo1.Lines.Add('连接成功');
end;
procedure TfMQTTForDelphi.IdTCPClient1Disconnected(Sender: TObject);
begin
Memo1.Lines.Add('连接断开');
end;
function FixedHeader(MessageType: TMQTTMessageType; Dup, Qos,Retain: Word): Byte; //固定头第一个字节
begin
{ Fixed Header Spec:
bit |7 6 5 4 | |3 | |2 1 | | 0 |
byte 1 |Message Type| |DUP flag| |QoS level| |RETAIN| }
Result := (Ord(MessageType) * 16) + (Dup * 8) + (Qos * 2) + (Retain * 1);
end;
function RemainingLength(x: Integer): TRemainingLength; //固定头第二个字节，动态长度1-4
var
byteindex: integer;
digit: integer;
begin
SetLength(Result, 1);
byteindex := 0;
while (x > 0) do
begin
digit := x mod 128;
x := x div 128;
if x > 0 then
begin
digit := digit or 128;
end;
Result[byteindex] := digit;
if x > 0 then
begin
inc(byteindex);
SetLength(Result, Length(Result) + 1);
end;
end;
end;
function VariableHeader_Connect(KeepAlive: Word): TBytes;
const
MQTT_PROTOCOL = 'MQTT';
MQTT_VERSION = 4;//V3.1.1协议级别为4.非3了
var
Qos, Retain: word;
iByteIndex: integer;
ProtoBytes: TUTF8Text;
ConnectFlag:Byte;//连接标志
begin
SetLength(Result, 10); //长度为10
iByteIndex := 0;
ProtoBytes := StrToBytes(MQTT_PROTOCOL, true);
CopyIntoArray(Result, ProtoBytes, iByteIndex); //协议名
Inc(iByteIndex, Length(ProtoBytes));
Result[iByteIndex] := MQTT_VERSION; //版本号
Inc(iByteIndex);
asm
mov ConnectFlag,11000010B //UserName,Pwd,CleanSession为1，其余均为0
end;
Result[iByteIndex] := ConnectFlag;//连接标志
Inc(iByteIndex);
Result[iByteIndex] := 0; //保持连接时间第一位
Inc(iByteIndex);
Result[iByteIndex] := KeepAlive; //保持连接时间第二位
end;
procedure CopyIntoArray(var DestArray: Array of Byte; SourceArray: Array of Byte; StartIndex: integer);
begin
Assert(StartIndex >= 0);
Move(SourceArray[0], DestArray[StartIndex], Length(SourceArray));
end;
function StrToBytes(str: string; perpendLength: boolean): TUTF8Text;
var
i, offset: integer;
begin
{ This is a UTF-8 hack to give 2 Bytes of Length followed by the string itself. }
if perpendLength then
begin
SetLength(Result, Length(str) + 2);
Result[0] := Length(str) div 256;
Result[1] := Length(str) mod 256;
offset := 1;
end
else
begin
SetLength(Result, Length(str));
offset := -1;
end;
for I := 1 to Length(str) do
Result[i + offset] := ord(str[i]);
end;
procedure AppendArray(var Dest: TUTF8Text; Source: Array of Byte);
var
DestLen: Integer;
begin
DestLen := Length(Dest);
SetLength(Dest, DestLen + Length(Source));
Move(Source, Dest[DestLen], Length(Source));
end;
function BuildCommand(FixedHeader: Byte; RemainL: TRemainingLength; VariableHead: TBytes; Payload: Array of Byte): TBytes; //构建最终的发送数据包
var
iNextIndex: integer;
begin
// Attach Fixed Header (1 byte)
iNextIndex := 0;
SetLength(Result, 1);
Result[iNextIndex] := FixedHeader;
// Attach RemainingLength (1-4 bytes)
iNextIndex := Length(Result);
SetLength(Result, Length(Result) + Length(RemainL));
CopyIntoArray(Result, RemainL, iNextIndex);
// Attach Variable Head
iNextIndex := Length(Result);
SetLength(Result, Length(Result) + Length(VariableHead));
CopyIntoArray(Result, VariableHead, iNextIndex);
// Attach Payload.
iNextIndex := Length(Result);
SetLength(Result, Length(Result) + Length(Payload));
CopyIntoArray(Result, Payload, iNextIndex);
end;
procedure AppendBytes(var DestArray: TBytes;const NewBytes: TBytes);
var
DestLen: Integer;
begin
DestLen := Length(DestArray);
SetLength(DestArray, DestLen + Length(NewBytes));
Move(NewBytes, DestArray[DestLen], Length(NewBytes));
end;
function RemainingLengthToInt(RLBytes: TBytes): Integer;
var
multi: integer;
i: integer;
digit: Byte;
begin
multi := 1;
i := 0;
Result := 0;
digit := RLBytes[i];
repeat
digit := RLBytes[i];
Result := Result + (digit and 127) * multi;
multi := multi * 128;
Inc(i);
until ((digit and 128) = 0);
end;
end.
{MQTT包格式如下：
[Fixed header]+[Variable header]+[Payload]
[Fixed header]: FixedHeader+RemainingLength
[Variable header] : 报文标识符
[Payload]：有效荷载
[CONNECT]:客户端发起连接
格式如下:
[Fixed header]: FixedHeader+RemainingLength
[Variable header] :协议名+协议级别+连接标志+保持连接
04MQTT+$4+Flag+Time
[Payload]: ClientId+User+Pwd
}后来测试以上代码在win32正常，安卓平台需要修改一下字符串的编码函数。需要注意。
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