angular – 缺少必需参数：在ionic2中访问google令牌时的grant_type

错误：-

{
  "error" : "invalid_request","error_description" : "required parameter is missing: grant_type"
}

码

let creds=JSON.Stringify({
        'client_id':'251059024984-8113pdtb11gm8m4evdq59stlpvcab8cn.apps.googleusercontent.com','client_secret':'uVWZt_Vd5mMLXGQDo7lmAIUe','redirect_uri':'http://localhost/callBACk','grant_type':'authorization_code','code':data
    });
    var headers = new Headers();
    headers.append('Content-Type','application/x-www-form-urlencoded');
    console.log(data)


    this.http.post('https://accounts.google.com/o/oauth2/token',creds,{headers: headers}).map(res => res.json()).subscribe(data => {
        console.log(data)
    },(error)=>{
        console.log('error in',error);
    })

当我检查邮递员的api工作完美