防止IE11在Angular 2中缓存GET调用

我有一个休息端点，可以在GET调用中返回列表。我也有一个POST端点来添加新项目，而DELETE来删除它们。这在Firefox和Chrome中有效，而POST和DELETE在IE11中有效。但是，IE11中的GET仅在页面的初始加载时有效。刷新将返回缓存的数据。我已经在Angular 1中看到有关此行为的帖子，但对于Angular 2（发布候选版本1）则一无所获。

今天，我也遇到了这个问题，（该死的IE）。在我的项目中，我httpclient没有使用BaseRequestOptions。我们应该用Http_Interceptor它来解决！

import { HttpHandler,
    HttpProgressEvent,
    HttpInterceptor,
    HttpSentEvent,
    HttpHeaderResponse,
    HttpUserEvent,
    HttpRequest,
    HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';

export class CustomHttpInterceptorService implements HttpInterceptor {
    intercept(req: HttpRequest<any>, next: HttpHandler):
      Observable<HttpSentEvent | HttpHeaderResponse | HttpProgressEvent | HttpResponse<any> | HttpUserEvent<any>> {
      const nextReq = req.clone({
        headers: req.headers.set('Cache-Control', 'no-cache')
          .set('Pragma', 'no-cache')
          .set('Expires', 'Sat, 01 Jan 2000 00:00:00 GMT')
          .set('If-Modified-Since', '0')
      });

      return next.handle(nextReq);
  }
}

模块提供

@NgModule({
    ...
    providers: [
        ...
        { provide: HTTP_INTERCEPTORS, useClass: CustomHttpInterceptorService, multi: true }
    ]
})

对于Angular 2和更高版本，通过重写添加无缓存标头的最简单方法是RequestOptions：

import { Injectable } from '@angular/core';
import { BaseRequestOptions, Headers } from '@angular/http';

@Injectable()
export class CustomRequestOptions extends BaseRequestOptions {
    headers = new Headers({
        'Cache-Control': 'no-cache',
        'Pragma': 'no-cache',
        'Expires': 'Sat, 01 Jan 2000 00:00:00 GMT'
    });
}

模块：

@NgModule({
    ...
    providers: [
        ...
        { provide: RequestOptions, useClass: CustomRequestOptions }
    ]
})

转发$ http的stackoverflow响应Angular IE Caching问题，您应该将标头“ Pragma”，“ no-cache”，“ If-Modified-Since”添加到每个“ GET”请求中。

拦截器的场景不再支持角度2。因此，您应该按照此处的说明扩展http。angular2中的httpinterceptor等效项是什么？。

Angular 4.3现在包括支持拦截器的HttpClient服务。

编辑：请参阅下面的评论-这是没有必要的（在大多数情况下）。

在以上Jimmy Ho的回答的基础上，我只想防止缓存我的API调用，而不是希望从缓存中受益的其他静态内容。我所有的API调用都是针对包含“ / api /”的URL，因此，我对Jimmy Ho的代码进行了修改，使其仅在所请求的URL包含“ / api /”的情况下才添加缓存头：

import { HttpHandler,
    HttpProgressEvent,
    HttpInterceptor,
    HttpSentEvent,
    HttpHeaderResponse,
    HttpUserEvent,
    HttpRequest,
    HttpResponse } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';

export class CustomHttpInterceptorService implements HttpInterceptor {
    intercept(req: HttpRequest<any>, next: HttpHandler):
    Observable<HttpSentEvent | HttpHeaderResponse | HttpProgressEvent | HttpResponse<any> | HttpUserEvent<any>> {
    // Only turn off caching for API calls to the server.
    if (req.url.indexOf('/api/') >= 0) {
        const nextReq = req.clone({
            headers: req.headers.set('Cache-Control', 'no-cache')
                .set('Pragma', 'no-cache')
                .set('Expires', 'Sat, 01 Jan 2000 00:00:00 GMT')
                .set('If-Modified-Since', '0')
        });

        return next.handle(nextReq);
    } else {
        // Pass the request through unchanged.
        return next.handle(req);
    }
}

}

如上所述，您可以使用http请求拦截器修改或设置请求的新标头。下面是在HTTP请求拦截器上为以后的Angular版本（Angular 4+）设置标头的简单得多的方法。这种方法只会设置或更新某个请求标头。这是为了避免删除或覆盖一些重要的标头，例如授权标头。

// cache-interceptor.service.ts
import { Injectable } from '@angular/core';
import {
  HttpInterceptor,
  HttpRequest,
  HttpHandler,
} from '@angular/common/http';

@Injectable()
export class CacheInterceptor implements HttpInterceptor {

  intercept(req: HttpRequest<any>, next: HttpHandler) {
    const httpRequest = req.clone({
      headers: req.headers
        .set('Cache-Control', 'no-cache')
        .set('Pragma', 'no-cache')
        .set('Expires', 'Sat, 01 Jan 2000 00:00:00 GMT')
    })

    return next.handle(httpRequest)
  }
}

// app.module.ts

  import { HTTP_INTERCEPTORS } from '@angular/common/http'
  import { CacheInterceptor } from './cache-interceptor.service';

  // on providers
  providers: [{ provide: HTTP_INTERCEPTORS, useClass: CacheInterceptor, multi: true }]

禁用带有元HTML标签的浏览器缓存：-

<meta http-equiv="cache-control" content="no-cache, must-revalidate, post-check=0, pre-check=0">
<meta http-equiv="expires" content="0">
<meta http-equiv="pragma" content="no-cache">

有点晚了，但是我遇到了同样的问题。对于Angular 4.X， 我编写了一个自定义Http类，将一个随机数附加到末尾以防止IE进行缓存。它基于dimeros的第二个链接（angular2中的httpinterceptor等效项是什么？）。警告：不能保证是100％无错误。

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { Http, Response, XHRBackend, RequestOptions, RequestOptionsArgs, 
URLSearchParams } from '@angular/http';

@Injectable()
export class NoCacheHttp extends Http {
    constructor(backend: XHRBackend, options: RequestOptions) {
        super(backend, options);
    }

    get(url: string, options?: RequestOptionsArgs): Observable<Response> {
        //make options object if none.
        if (!options) {
            options = { params: new URLSearchParams() };
        }
        //for each possible params type, append a random number to query to force no browser caching.
        //if string
        if (typeof options.params === 'string') {
            let params = new URLSearchParams(options.params);
            params.set("k", new Date().getTime().toString());
            options.params = params;

        //if URLSearchParams
        } else if (options.params instanceof URLSearchParams) {
            let params = <URLSearchParams>options.params;
            params.set("k", new Date().getTime().toString());

        //if plain object.
        } else {
            let params = options.params;
            params["k"] = new Date().getTime().toString();
        }
        return super.get(url, options);
    }
}