百度API车牌识别——Restful方式

源码下载地址：https://download.csdn.net/download/redhat588/11798294

Delphi xe 10.3.2 for windows 7 环境编译通过！

测式需要先注册百度API账号，拿到API KEY 和Secret Key后才能获取Token值

第一步：首先获取Token地址

 function TfrmMain.GetToken(TokenUrl, lbledtAPIKEY, lbledtSecretKey
   : string): string;
 begin
   with RESTClient1 do
   begin
     BaseURL := TokenUrl;
   end;
   with RESTRequest1 do
   begin
     Method := rmPOST;
     AcceptCharSet := 'utf-8';
     Params.Clear;
     AddParameter('grant_type', 'client_credentials');
     AddParameter('client_id', lbledtAPIKEY);
     // API ID   key
     AddParameter('client_secret', lbledtSecretKey);
     // API secret  key
     Execute;
     Result := RESTResponse1.Content;
   end;
 end;

 function TfrmMain.GetAccessToken(jsonstr: string): string; // 取jsonstring 值
 var
   jo: TjsonObject;
   jv: TjsonValue;
 begin
   jo := nil;
   jo := TjsonObject.Create;
   jo := TjsonObject.parsejsonvalue(Tencoding.utf8.getbytes(jsonstr), )
     as TjsonObject;
   jv := jo.Get('access_token').JsonValue;
   Result := jv.Value;
 end;

 procedure TfrmMain.Button1Click(Sender: TObject);
 begin
   lbledtToken.Text := GetAccessToken(GetToken(lbledtTokenUrl.Text,
     lbledtAPIKEY.Text, lbledtSecretKey.Text));
 end;

第二步：识别车牌

function TfrmMain.GetCarNumJson(AccessToken, CarNumAPI: string): string;
var
  strtemp: string;
  temp: TjsonObject;
  strm: TMemoryStream;
  ss: TStringStream;
  s: string;
begin
  if frmMain.Image1.Picture.Graphic <> nil then
  begin
    strm := TMemoryStream.Create;
    frmMain.Image1.Picture.SaveToStream(strm);
    ss := TStringStream.Create('');
    strm.Position := ;
    EncodeStream(strm, ss); // 将内存流编码为base64字符流
    s := ss.DataString;
    strm.Free;
    ss.Free;
  end;
  RESTClient1.BaseURL := CarNumAPI;
  RESTRequest1.Params.Clear;
  RESTRequest1.AddParameter('access_token', AccessToken);
  RESTRequest1.AddParameter('image', s);
  RESTRequest1.Execute;
  Result := RESTResponse1.Content;
end;

function TfrmMain.GetCarNum(CarNumJSONStr: String): string;
var
  jo: TjsonObject;
  jo2: TjsonObject;
  jv: TjsonValue;
  jsonstr: string; // 要转换的json字符串
  jsonstr2: string; // 要转换的json字符串
begin
  // 先取出嵌套的那个字符串
  jo := TjsonObject.parsejsonvalue(CarNumJSONStr) as TjsonObject;
  jsonstr := jo.GetValue('words_result').ToString;
  // 再对这个字符串取值
  jo2 := TjsonObject.parsejsonvalue(jsonstr) as TjsonObject;
  jsonstr2 := jo.GetValue('words_result').ToString;
  try
    jv := jo2.Get('number').JsonValue;
    Result := jv.Value;
  finally
    jo.Free;
  end;
end;

procedure TfrmMain.Button2Click(Sender: TObject);
begin
  lbledtCarNum.Text := GetCarNum(GetCarNumJson(lbledtToken.Text,
    lbledtAPIURL.Text));
end;

最后：结果图