如何在 angular 5 中为每个 HTTP 请求显示微调器？

Question

我是 angular 5 的新手。如何编写一个通用函数来显示 angular 中每个 HTTP 请求的微调框 5.Please 帮助我实现这个。

Answer 1

这与 HttpClient 或 HTTP 请求无关。这是一个一般如何处理异步调用的问题（HTTP与否）。

你应该

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

并且在 ts 文件中：

loading: boolean = true;

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

Answer 2

您可以使用 Angular HttpInterceptor to show a spinner for all your requests, Here's a good medium article on how to implement an http interceptor

此外，您还必须创建一个微调器 service/module 并将其注入到您的 http 拦截器中。最后，在您的拦截方法中，您可以使用 finally rxJs 方法来停止您的微调器。这是一个简单的实现：

intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    this.spinnerService.start();
    return next.handle(req).finally(res => this.spinnerService.stop() );
}

尽情享受吧！

奖金：这是

Answer 3

您可以创建一个服务，然后在订阅它的应用程序的根级别向它发布事件。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;
}

然后您可以像这样发布和订阅事件：

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;
});

终于在 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耦合方式，可以实现您想要的任何加载程序。

Answer 4

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 函数显示加载程序，onXhrFinish 函数隐藏它。

完整的工作源代码和演示是 here

Answer 5

来源Link

创建服务

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

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

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

创建加载程序拦截器

    // 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();
                };
            });
        }
    }

现在创建一个加载器组件，然后添加到应用程序组件中

  //loader.interceptor.ts
  import { Component, OnInit } from '@angular/core';
  import { LoaderService } from '../loader.service';

  @Component({
    selector: 'app-loading',
    templateUrl: './loading.component.html',
    styleUrls: ['./loading.component.css']
  })
  export class LoaderComponent implements OnInit {

    loading: boolean;
    constructor(private loaderService: LoaderService) {
      this.loaderService.isLoading.subscribe((v) => {
        console.log(v);
        this.loading = v;
      });
    }
    ngOnInit() {
    }

  }

Answer 6

完整的指南是 here 和 material mat-progress-spinner 用法。很酷！

Answer 7

我在这里写了一些创建您自己的自定义进度条的步骤。

创建组件

从'@angular/core'导入{组件，输入}； @零件（{ 选择器：'app-sw-progressbar'，模板：<div *ngIf="loading"> <mat-progress-bar style="position:absolute; left:15px; width: calc(100% - 30px); height:5px;" color="primary" mode="indeterminate"> </mat-progress-bar> </div>， }) 导出 class SWProgresbarComponent { @Input() loading = false; 构造函数（）{} }

2 在模块中导入组件：-

import { SWProgresbarComponent } from '../sw-progressbar.component';
@NgModule({
declarations: [SWProgresbarComponent],
imports: [
CommonModule,
MaterialModule,
RouterModule
],
exports: [SWProgresbarComponent,
RouterModule
]
})
export class SharedModule { }

如何使用？

此处 loading 将在您要显示的组件中为 true。添加这个在您要显示加载程序的组件中的代码下方。

<app-sw-progressbar [loading]="loading"></app-sw-progressbar>

对于微调器，将 mat-progress-bar 替换为 mat-progress-spinner。

Answer 8

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 }               
    ]
})

最后在路由器插座内 app.component 添加您的微调器标签

 <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，我正在使用 NgxSpinner，但如果您使用的是自定义微调器，这应该没有什么区别，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。

如何在 angular 5 中为每个 HTTP 请求显示微调器？

How to Show spinner for every HTTP requests in angular 5?

angular-http

angular-http-interceptors

angular

angular-httpclient