BLOB到PDF下载使用Java和angular 5

Question

我正在尝试实现从angular 5上的数据库下载pdf的逻辑。我在下载文件中遇到问题。文件已下载，但在打开时引发错误-"加载失败"。

我看了很多博客和问题/答案，但没能在代码中找到错误。

In Database -> pdf file content saved as BLOB

Rest web服务->在下面的代码中，pdfData是来自BLOB类型列的数据，在这里的java代码中是byte[]

@GetMapping("downloadReport/{reportId}")
public StreamingResponseBody downloadDocument(byte[] pdfData) {
return outputStream -> {
//This way working for sample
/*try (InputStream inputStream = new ByteArrayInputStream(
Files.readAllBytes(Paths.get("D:/pdfWithoutPassword.pdf")))) {
IOUtils.copy(inputStream, outputStream);
}*/
//This way not working when data fetched from Database
try (InputStream inputStream = new ByteArrayInputStream(pdfData)) {
IOUtils.copy(inputStream, outputStream);
}
outputStream.close();
};

角度5码

downloadReport(reportType: string, reportId: string) {
let fileDownloadUrl = environment.apiUrl + "/downloadReport" + "/" + reportId;
return this.httpClient
.get(fileDownloadUrl, { observe: 'response', responseType: "blob"})
.subscribe(response => this.saveFileToSystem(response.body)),
error => console.log("Error downloading the file."),
() => console.info("OK");
}
saveFileToSystem(input: any) {
const blob = new Blob([input], { type: 'application/octet-stream' });
saveAs(blob, "testingpdf1.pdf");
}

寻求解决此问题的帮助。提前感谢！

Answer 1

这里是我做这件事的另一种方式，你可以更改：

@RequestMapping(value = "/generateReport", method = RequestMethod.POST)
public ResponseEntity<byte[]> generateReport(){
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.parseMediaType("application/pdf"));
StringBuilder filename = new StringBuilder("MyPdfName").append(".pdf");
byte[] bytes = pdfGeneratorService.generatePDF();
headers.add("content-disposition", "inline;filename=" + filename.toString());
headers.setCacheControl("must-revalidate, post-check=0, pre-check=0");
ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(bytes, headers, HttpStatus.OK);
return response;
}

Answer 2

试试这个：

从你的html页面

<a href="javascript:void(0);" (click)="generatePdf()"> YourPdf.pdf </a>

从你的js文件

generatePdf() {
this.yourService.generatePdf()
.subscribe(pdf => {
let mediaType = 'application/pdf';
let blob = new 
Blob([this.converterService.base64ToArrayBuffer(pdf.pdfByteArray)], { type: mediaType });
saveAs(blob, fileName);
}, err => {
console.log('Pdf generated err: ', JSON.stringify(err));
});

}

您的转换器服务：

import { Injectable } from "@angular/core";
@Injectable()
export class ConverterService {
base64ToArrayBuffer(base64) {
var binaryString = window.atob(base64);
var binaryLen = binaryString.length;
var bytes = new Uint8Array(binaryLen);
for (var i = 0; i < binaryLen; i++) {
var ascii = binaryString.charCodeAt(i);
bytes[i] = ascii;
}
return bytes;
}
}