从响应中提取图像数据:Angular 2 [英] Extracting Image Data from response: Angular 2

问题描述

响应中包含图像数据，但是我无法从响应中提取图像.

The response has the image data but I am unable to extract it from the response.

客户代码-

download() {
    this._http.get('http://localhost:9000/download/' + this._fileid)
    .subscribe(
    data => {
        this.image = data;
    },
    err => console.log('Error is..:' + err)
    );
}

服务器代码-

app.get('/download/:fileid', function(req, res) {
    var id = req.params.fileid;
    res.set('Content-Type', 'image/jpeg');
    gfs.createReadStream({_id: id}).pipe(res);
});

-我已经修改了我的代码以使用CustomXhr，但是我得到了一个没有数据的空blob.

- I have adapted my code to use CustomXhr but however I get an empty blob with no data.

自定义XHR代码-

@Injectable()
export class CustomBrowserXhr extends BrowserXhr {
  build(): any {
    let xhr = super.build();
    xhr.responseType = "blob";
    return <any>(xhr);
  }
}

自举代码-

export function main(initialHmrState?: any): Promise<any> {

  return bootstrap(App, [
    ...ENV_PROVIDERS,
    ...PROVIDERS,
    ...DIRECTIVES,
    ...PIPES,
    ...APP_PROVIDERS,
     provide(BrowserXhr, { useClass: CustomBrowserXhr })
  ])
  .catch(err => console.error(err));
}

HTTP请求-

download() {
  this._http.get('http://localhost:9000/download/' + this._fileid)
    .toPromise()
    .then(res => {
      if (res.headers.get("Content-Type").startsWith("image/")) {
          var blob = new Blob([new Uint8Array(res._body)], {
              type: res.headers.get("Content-Type")
          });
          var urlCreator = window.URL;
          var url = urlCreator.createObjectURL(blob);
          console.log(url);
          this.image = url;
      }
    })
}

推荐答案

您正在寻找的是arrayBuffer().您的代码将是:

What you are looking for is arrayBuffer(). Your code will be:

download() {
    this._http.get('http://localhost:9000/download/' + this._fileid)
    .subscribe(
    data => {
        this.image = data.arrayBuffer();
    },
    err => console.log('Error is..:' + err)
    );
}

但是，不幸的是，从版本13开始，尚未实现arrayBuffer().

But, unfortunately, arrayBuffer() is not yet implemented as of beta.13.

您可以改用XMLHttpRequest，这是一个小矮人

getImage(url:string){ 
 return Observable.create(observer=>{
  let req = new XMLHttpRequest();
  req.open('get',url);
  req.responseType = "arraybuffer";
  req.onreadystatechange = function() {
    if (req.readyState == 4 && req.status == 200) {
      observer.next(req.response);
      observer.complete();
    }
  };
  req.send();
 });
}

这篇关于从响应中提取图像数据:Angular 2的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！