Question

我是角色5的新手。如何编写一个通用函数来为角度为5的每个HTTP请求显示微调器。请帮我实现它。

Answer 1

你可以使用Angular HttpInterceptor来显示所有请求的微调器，这是一个很好的medium article on how to implement an http interceptor

此外，您必须创建一个微调器服务/模块并将其注入您的http拦截器。最后，在你的拦截方法中，你可以使用HWsort rxJs方法来阻止你的微调器。这是一个简单的实现：

finally

享受！

奖金：这是spinner service implementation example

Answer 2

这与HttpClient或HTTP请求无关。这是一个如何处理异步调用（HTTP或不是）的问题。

你应该

<div class="spinner" *ngIf="loading"; else showWhenLoaded"><div>
<ng-template #showWhenLoaded>
    <div>Your Content</div>
</ng-template>

并在ts文件中：

loading: boolean = true;

methodToTriggerRequest() {
    this.loading = true;
    this.http.get(...).subscribe(response => {
        if (resposnseNotAnError(response)) {this.loading = false}
    })
}

Answer 3

您可以创建服务，然后在订阅它的应用程序的根级别中向其发布事件。让我解释一下。

broadcast.service.ts （这是您的服务）

import { Injectable } from '@angular/core';

import { Subject } from 'rxjs/Subject';
import { Subscription } from 'rxjs/Subscription';

import 'rxjs/add/operator/filter'
import 'rxjs/add/operator/map'

/**
 * This class acting as event service bus for the entire app.
 * No Need to register the class as this registered in the root level.
 * Can just inject to componets.
 */
@Injectable()
export class BroadcastService {

    private _handler: Subject<Message> = new Subject<Message>();

    broadcast(type: string, payload: any = null) {
        this._handler.next({ type, payload });
    }

    subscribe(type: string, callback: (payload: any) => void): Subscription {
        return this._handler
            .filter(message => message.type === type)
            .map(message => message.payload)
            .subscribe(callback);
    }
}

interface Message {
    type: string;
    payload: any;
}

然后你可以发布和订阅这样的事件：

您的服务水平：

this.broadcastService.broadcast('PROGRESS_START');

在您的应用组件级别：

this.broadcastService.subscribe('PROGRESS_START', ()=>{
  //hit when you start http call
  this.myLoader = true;
});

最后在app.component.html：

<div *ngIf="myLoader">
 <!--YOUR LOADER SHOULD GO HERE-->
</div>
<router-outlet></router-outlet>

这是一种非常通用的松散耦合方式，可以实现您想要的任何加载器。

Answer 4

来源Link

创建服务

events.js:173
      throw er; // Unhandled 'error' event
      ^

Error: spawn cmd ENOENT
    at Process.ChildProcess._handle.exit (internal/child_process.js:248:19)
    at onErrorNT (internal/child_process.js:431:16)
    at processTicksAndRejections (internal/process/task_queues.js:83:17)
Emitted 'error' event at:
    at Process.ChildProcess._handle.exit (internal/child_process.js:254:12)
    at onErrorNT (internal/child_process.js:431:16)
    at processTicksAndRejections (internal/process/task_queues.js:83:17)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! my-app@0.1.0 start: `react-scripts start`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the my-app@0.1.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\Dhruvi\AppData\Roaming\npm-cache\_logs\2019-04-30T01_57_22_780Z-debug.log

创建装载程序拦截器

//loader.service.ts
import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class LoaderService {

  public isLoading = new BehaviorSubject(false);
  constructor() { }
}

现在创建一个加载程序组件，然后添加应用程序组件

    // loader.interceptors.ts
    import { Injectable } from '@angular/core';
    import {
        HttpErrorResponse,
        HttpResponse,
        HttpRequest,
        HttpHandler,
        HttpEvent,
        HttpInterceptor
    } from '@angular/common/http';
    import { Observable } from 'rxjs';
    import { LoaderService } from './loader.service';

    @Injectable()
    export class LoaderInterceptor implements HttpInterceptor {
        private requests: HttpRequest<any>[] = [];

        constructor(private loaderService: LoaderService) { }

        removeRequest(req: HttpRequest<any>) {
            const i = this.requests.indexOf(req);
            if (i >= 0) {
                this.requests.splice(i, 1);
            }
            this.loaderService.isLoading.next(this.requests.length > 0);
        }

        intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

            this.requests.push(req);
            console.log("No of requests--->" + this.requests.length);
            this.loaderService.isLoading.next(true);
            return Observable.create(observer => {
                const subscription = next.handle(req)
                    .subscribe(
                        event => {
                            if (event instanceof HttpResponse) {
                                this.removeRequest(req);
                                observer.next(event);
                            }
                        },
                        err => {
                            alert('error returned');
                            this.removeRequest(req);
                            observer.error(err);
                        },
                        () => {
                            this.removeRequest(req);
                            observer.complete();
                        });
                // remove request from queue when cancelled
                return () => {
                    this.removeRequest(req);
                    subscription.unsubscribe();
                };
            });
        }
    }

Answer 5

完整的指南是here，使用的是mat-progress-spinner。太酷了！

Answer 6

创建拦截器服务

import { Injectable } from '@angular/core';
import { HttpEvent, HttpHandler, HttpInterceptor, HttpRequest } from '@angular/common/http';
import { Observable } from 'rxjs';
import { finalize } from 'rxjs/operators';
import { NgxSpinnerService } from 'ngx-spinner';

@Injectable()
export class SpinnerInterceptor implements HttpInterceptor {

    constructor(private spinner: NgxSpinnerService) { }

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        this.spinner.show();
        return next.handle(req).pipe(
            finalize(() => this.spinner.hide())
        );
    }
}

在应用模块中提供此服务

import { HTTP_INTERCEPTORS } from '@angular/common/http';
                 
        ....
             
@NgModule({       
    providers: [
        { provide: HTTP_INTERCEPTORS, useClass: SpinnerInterceptor, multi: true }               
    ]
})

最后在路由器出口内的 app.component 添加您的微调标签

 <router-outlet>
    <ngx-spinner bdColor="rgba(0,0,0,0.8)"
                 size="medium"
                 color="#fff"
                 type="timer">
        <p style="color: #fff"> Loading... </p>
    </ngx-spinner>
</router-outlet>

如您所见，我使用的是 NgxSpinner，但如果您使用自定义微调器，这应该没有区别，您只需要创建服务来显示和隐藏微调器并将此服务注入微调器拦截器。

Answer 7

在Angular的拦截器中，我使用了“ do”运算符。

intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    // handler for both success and fail response
    const onReqFinish = (event: HttpEvent<any>) => {
      if (event.type === 4) {
        this.onXhrFinish();
      }
    };

    this.onXhrStart();

    return next.handle(req)
     .do(
       onReqFinish,
       onReqFinish
     );
}

onXhrStart函数显示一个加载器，onXhrFinish隐藏它。

完整的工作源代码和演示是here

如何在角度5中显示每个HTTP请求的微调器？

7 个答案: