我进行第一次http调用,然后当subscribe触发时,它调用completeLogin.然后,我可以使用自己的完整函数触发另一个http调用并重复链接.

这是组件代码.用户已填写登录信息并按下登录信息：

onSubmit() {
   console.log(' in on submit');
   this.localUser.email = this.loginForm.controls["email"].value;
   this.localUser.password = this.loginForm.controls["password"].value;
   this.loginMessage = "";
   this.checkUserValidation();
}

checkUserValidation() { 
   this.loginService.getLoggedIn()
      .subscribe(loggedIn => {
         console.log("in logged in user validation")
         if(loggedIn.error != null || loggedIn.error != undefined || loggedIn.error != "") {
            this.loginMessage = loggedIn.error;
         }
      });

      this.loginService.validateUser(this.localUser);
}

这将调用loginservice ValidateUser方法

validateUser(localUser: LocalUser) {
   this.errorMessage = "";
   this.email.email = localUser.email;
   var parm = "validate~~~" + localUser.email + "/"
   var creds = JSON.stringify(this.email);
   var headers = new Headers();
   headers.append("content-type",this.constants.jsonContentType);

   console.log("making call to validate");
   this.http.post(this.constants.taskLocalUrl + parm,{ headers: headers })
      .map((response: Response) => {
         console.log("json = " + response.json());
         var res = response.json();
         var result = <AdminResponSEObject>response.json();
         console.log(" result: " + result);
         return result;
      })
      .subscribe(
         aro => {
            this.aro = aro
         },error => {
            console.log("in error");
            var errorObject = JSON.parse(error._body);
            this.errorMessage = errorObject.error_description;
            console.log(this.errorMessage);
         },() => this.completeValidateUser(localUser));
            console.log("done with post");
     }

completeValidateUser(localUser: LocalUser) {
   if (this.aro != undefined) {
      if (this.aro.errorMessage != null && this.aro.errorMessage != "") {
         console.log("aro err " + this.aro.errorMessage);
         this.setLoggedIn({ email: localUser.email,password: localUser.password,error: this.aro.errorMessage });
      } else {
         console.log("log in user");
         this.loginUser(localUser);
      }
   } else {
      this.router.navigate(['/verify']);
   }

}

在我的登录服务中,我调用授权服务,该服务返回一个可观察的令牌.

loginUser(localUser: LocalUser) {
   this.auth.loginUser(localUser)
   .subscribe(
      token => {
         console.log('token = ' + token)
         this.token = token
      },error => {
         var errorObject = JSON.parse(error._body);
         this.errorMessage = errorObject.error_description;
         console.log(this.errorMessage);
         this.setLoggedIn({ email: "",password: "",error: this.errorMessage });
      },() => this.completeLogin(localUser));
}

在授权服务中：

loginUser(localUser: LocalUser): Observable<Token> {
   var email = localUser.email;
   var password = localUser.password;

    var headers = new Headers();
    headers.append("content-type",this.constants.formEncodedContentType);

    var creds:string = this.constants.grantString + email + this.constants.passwordString + password;
    return this.http.post(this.constants.tokenLocalUrl,creds,{ headers: headers })
         .map(res => res.json())
}

此代码中的要点是,首先调用登录服务的validateUser方法,在响应时,根据返回信息,如果有效,我在登录服务上调用loginUser方法.只要你需要,这条链就可以继续.您可以设置类级变量以保存链中每个方法所需的信息,以便决定下一步做什么.

另请注意,您可以订阅服务中的返回并在那里处理它,它不必返回到组件.

好的,这里是：

public getShows():any {
   this._ShowsHttpService
      .getShows()
      .subscribe(
         w => this.shows = w,error => this.errorMessage = error,() => this.completeGetShows());
}

completeGetShow() {

   //any logic here to deal with prevIoUs get;

   this.http.get#2()
      .subscribe(
         w => this.??? = w),error => this.error = error,() => this.completeGet#2);
}

completeGet#2() {

   //any logic here to deal with prevIoUs get;

   this.http.get#3()
      .subscribe(
         w => this.??? = w),() => this.completeGet#3);
}

completeGet#3() {

   //any logic here to deal with prevIoUs get;

   //another http: call like above to infinity....
}