Open pdf from bytes array in angular 5

问题

I was following the below links for displaying pdf page in new tab in my angular 5 application. But unable to achieve the result.

I am consuming the bytes array from spring controller api.

PDF Blob is not showing content, Angular 2

PDF Blob - Pop up window not showing content

Angular2 Displaying PDF

I tried the below options but none of them is working.

Trial 1

Consumed the response as json

component.ts

clickEvent(){
this.service.getPDF().subscribe((response)=>{

  let file = new Blob([response.byteString], { type: 'application/pdf' });            
  var fileURL = URL.createObjectURL(file);
  window.open(fileURL);
})

}

service.ts

getPDF(){
const url = `${this.serviceUrl}/pdf`;

const httpOptions = {
  headers: new HttpHeaders(
    {
      'Accept': 'application/json',
      'responseType':'blob'
    }
  )
};

return this.http.get<any>(url, httpOptions);

}

Trial 2

Consumed the response as json

component.ts

clickEvent(){
this.service.getPDF().subscribe((response)=>{

  let file = new Blob([response.byteArray], { type: 'application/pdf' });            
  var fileURL = URL.createObjectURL(file);
  window.open(fileURL);
})

}

service.ts

getPDF(){
const url = `${this.serviceUrl}/pdf`;

const httpOptions = {
  headers: new HttpHeaders(
    {
      'Accept': 'application/json',
      'responseType':'arraybuffer'
    }
  )
};

return this.http.get<any>(url, httpOptions);

}

Trial 3

Consumed the response as bytes

component.ts

clickEvent(){
this.service.getPDF().subscribe((response)=>{

  let file = new Blob([response], { type: 'application/pdf' });            
  var fileURL = URL.createObjectURL(file);
  window.open(fileURL);
})

}

service.ts

getPDF(){
const url = `${this.serviceUrl}/pdf`;

const httpOptions = {
  headers: new HttpHeaders(
    {
      'responseType':'blob'                 //both combination
      //'responseType'  : 'arraybuffer'
    }
  )
};

return this.http.get<any>(url, httpOptions);

}

By all the combination I am only getting two results. Empty pdf document or Failed to load PDF document.

For understanding posting java spring controller code.

controller.java

@GetMapping(value = "/pdf")
public ResTest generatePDF(HttpServletResponse response) throws IOException {
    ResTest test = new ResTest();
    ByteArrayOutputStream baos = docTypeService.createPdf();
    test.setByteArray(baos.toByteArray());
    test.setByteString(new String(baos.toByteArray()));
    return test;
}

回答1:

At last, I was able to render pdf. There were two small mistakes from my side.

1 st Problem was, I gave 'responseType' inside HttpHeaders which was wrong. It should be outside as below.

2 nd Problem was, even though if you mention as responseType : 'arraybuffer', it was unable to take it. For that you need to mention as responseType : 'arraybuffer' as 'json'.(Reference)

The corrected and working code below.

Trial 3

component.ts (nochanges)

clickEvent(){
  this.service.getPDF().subscribe((response)=>{

  let file = new Blob([response], { type: 'application/pdf' });            
  var fileURL = URL.createObjectURL(file);
  window.open(fileURL);
})

service.ts

getPDF(){
const url = `${this.serviceUrl}/pdf`;

const httpOptions = {
  'responseType'  : 'arraybuffer' as 'json'
   //'responseType'  : 'blob' as 'json'        //This also worked
};

return this.http.get<any>(url, httpOptions);

}

Referred from the below link

https://github.com/angular/angular/issues/18586

回答2:

I had the same problem with angular and pdf display. I will describe my solution - use base64 encoded string. All modern browsers support base64.

Use import java.util.Base64 to decode your byte array

byte[] bytes = baos.toByteArray();

String string = Base64.getEncoder().encodeToString(bytes);

test.setByteString(string);

On the frontend side use standard mime type for pdf and indicate that you are using base64 data:application/pdf;base64,.

Ref. to mime types: https://en.wikipedia.org/wiki/Media_type

If you need to open document in a new window:

let newPdfWindow = window.open("","Print");

let content = encodeURIComponent(response.byteString);

let iframeStart = "<\iframe width='100%' height='100%' src='data:application/pdf;base64, ";

let iframeEnd = "'><\/iframe>";

newPdfWindow.document.write(iframeStart + content + iframeEnd);

If you need to open in a new tab, you may simply provide to your html href:
```
let pdfHref = this.sanitizer.bypassSecurityTrustUrl('data:application/octet-stream;base64,' + content);
```
bypassSecurityTrustUrl will sanitize your url. As I remember there was some problem with angular security, that prevented me from seeing the content.

PS. before checking how it works with angular I would like to recommend you to store the pdf file on a drive and try to open it. I mean, that you should be certainly sure that you file is valid and you may open it with simple reader.

Update. The simpliest solution is to use pdf.js library https://github.com/mozilla/pdf.js

回答3:

Have you looked for an angular component to wrap pdf.js?

https://github.com/VadimDez/ng2-pdf-viewer

Sample usage:

<pdf-viewer [src]="pdfSrc" 
    [render-text]="true"
    style="display: block;">
</pdf-viewer>

pdfSrc can be a url string or a UInt8Array

来源：https://stackoverflow.com/questions/50260391/open-pdf-from-bytes-array-in-angular-5

标签

java

pdf

angular5