处理多部分响应体的角度

this other post 在stackoverflow上创建了一个http拦截器类,该类显示如何解析多部分响应。 拦截器将第一个“application/json”部分作为多部分响应的响应体返回( multipart/mixed multipart/form-data 或 multipart/related ). 通过映射,可以很容易地将其他内容类型的其他解析器添加到类中。

import { HttpEvent, HttpHandler, HttpInterceptor, HttpRequest, HttpResponse } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@Injectable({
  providedIn: 'root',
})

export class MultipartInterceptService implements HttpInterceptor {

  private parserMap = {
    'application/json': JSON.parse,
  };

  private parseMultipart(multipart: string, boundary: string): any {
    const dataArray: string[] = multipart.split(`--${boundary}`);
    dataArray.shift();
    dataArray.forEach((dataBlock) => {
      const rows = dataBlock.split(/\r?\n/).splice(1, 4);
      if (rows.length < 1) {
        return;
      }
      const headers = rows.splice(0, 2);
      const body = rows.join('');
      if (headers.length > 1) {
        const pattern = /Content-Type: ([a-z\/+]+)/g;
        const match = pattern.exec(headers[0]);
        if (match === null) {
          throw Error('Unable to find Content-Type header value');
        }
        const contentType = match[1];
        if (this.parserMap.hasOwnProperty(contentType) === true) {
          return this.parserMap[contentType](body);
        }
      }
    });
    return false;
  }

  private parseResponse(response: HttpResponse<any>): HttpResponse<any> {
    const contentTypeHeaderValue = response.headers.get('Content-Type');
    const body = response.body;
    const contentTypeArray = contentTypeHeaderValue.split(';');
    const contentType = contentTypeArray[0];
    switch (contentType) {
      case 'multipart/related':
      case 'multipart/mixed':
      case 'multipart/form-data':
        const boundary = contentTypeArray[1].split('boundary=')[1];
        const parsed = this.parseMultipart(body, boundary);
        if (parsed === false) {
          throw Error('Unable to parse multipart response');
        }
        return response.clone({ body: parsed });
      default:
        return response;
    }
  }

  // intercept request and add parse custom response
  public intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(request)
      .pipe(
        map((response: HttpResponse<any>) => {
          if (response instanceof HttpResponse) {
            return this.parseResponse(response);
          }
        }),
      );
  }
}

代码从 Content-Type 响应头并使用此边界将响应体拆分为块。然后它尝试解析每个部分并返回第一个成功解析的部分 application/json

注: