Question

我想使用以下Angular 6代码实现文件下载：

其他API：

@GetMapping("export")
    public ResponseEntity<InputStreamResource> export() throws IOException {
        ClassPathResource pdfFile = new ClassPathResource(EXTERNAL_FILE_PATH);

        HttpHeaders headers = new HttpHeaders();
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");

        return ResponseEntity.ok().headers(headers).contentLength(pdfFile.contentLength())
                .contentType(MediaType.parseMediaType("application/pdf"))
                .body(new InputStreamResource(pdfFile.getInputStream()));
    }

服务：

import {Injectable} from '@angular/core';
import {HttpClient, HttpParams} from "@angular/common/http";
import {Observable} from "rxjs/index";
import {environment} from "../../../environments/environment";
import {HttpUtils} from "../common/http-utils";
import { map } from 'rxjs/operators';

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

  constructor(private http: HttpClient) {
  }

  downloadPDF(): any {
    return this.http.get(environment.api.urls.downloads.getPdf, { responseType: 'blob' }).map(
    (res) => {
        return new Blob([res.blob()], { type: 'application/pdf' });
    });
  }  
}

组件：

import {Component, OnInit} from '@angular/core';
import {DownloadService} from "../service/download.service";
import {ActivatedRoute, Router} from "@angular/router";
import {flatMap} from "rxjs/internal/operators";
import {of} from "rxjs/index";
import { map } from 'rxjs/operators';

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

  constructor(private downloadService: DownloadService,
              private router: Router,
              private route: ActivatedRoute) {
  }

  ngOnInit() {   
  }

  export() {               
    this.downloadService.downloadPDF().subscribe(res => {
      const fileURL = URL.createObjectURL(res);
      window.open(fileURL, '_blank');
    });         
  } 
}

当我开始倾斜时，出现错误：src / app / panel / service / download.service.ts（17,91）中的错误：错误TS2339：“可观察”类型上不存在属性“地图”。

将map导入代码的正确原因是什么？当我按下下载按钮时，没有任何反应。

Answer 1

您可能正在使用Rxjs 5.5或更高版本。

在Rxjs 5.5之后，您不再可以直接在可观察值上链接像map这样的运算符。您必须使用.pipe，然后再传递以逗号分隔的运算符列表。

import { map } from 'rxjs/operators';
...
downloadPDF(): any {
  return this.http.get(environment.api.urls.downloads.getPdf, {
    responseType: 'blob',
    observe: 'response'
  })
  .pipe(
    map((res: any) => {
      return new Blob([res.blob()], { type: 'application/pdf' });
    })
  );
}

这是您推荐的Sample StackBlitz。

顺便说一句，Explorer是一个很棒的工具，可以检查Rxjs语法到目前为止的变化。

Answer 2

由于使用的是角度6，因此您可以像这样调用请求

downloadPDF(): any {
    return this.http.get(environment.api.urls.downloads.getPdf, { responseType: 'blob' });
  }

更新：导入ResponseContentType

从'@ angular / http'导入{Http，ResponseContentType};

类型“ Observable <blob>”上不存在属性“ map”

2 个答案: