Question

我正在使用Web API（使用Spring Boot）进行工作，该Web API使用外部C ++ api转换pdf，该程序正在运行，但是当我要在正文响应中发送文件时，出现此错误：

{
"timestamp": "2019-04-10T09:56:01.696+0000",
"status": 500,
"error": "Internal Server Error",
"message": "file [D:\\[Phenix-Monitor]1.pdf] cannot be resolved in the file system for checking its content length",
"path": "/convert/toLinPDf"}

控制器：

@PostMapping("/toLinPDf")
public ResponseEntity<ByteArrayResource> convertion(@RequestParam(value = "input", required = false) String in,
        @RequestParam(value = "output", required = false) String out) throws IOException, InterruptedException {
    linearizeService.LinearizePDf(in, out);
    FileSystemResource pdfFile = new FileSystemResource(out);
    return ResponseEntity
            .ok()
            .contentLength(pdfFile.contentLength())
            .contentType(
                    MediaType.parseMediaType("application/pdf"))
            .body(new ByteArrayResource(IOUtils.toByteArray(pdfFile.getInputStream())));

}

我想问题出在linearizeService.LinearizePDf(in, out);中，因为在这种方法中我正在使用外部进程，所以发生的是，当我尝试使用FileSystemResource pdfFile = new FileSystemResource(out);打开文件时，linearizeService确实做了尚未完成处理，为什么我会收到此错误，我的问题是：我该如何处理，我的意思是如何等待文件创建后再发送该文件？

Answer 1

我建议您使用Java 8的Future API。

这是您资源的更新。

@PostMapping("/toLinPDf")
public ResponseEntity<ByteArrayResource> convertion(
    @RequestParam(value = "input", required = false) String in,
    @RequestParam(value = "output", required = false) String out) throws IOException, InterruptedException {
ExecutorService executorService = Executors.newSingleThreadExecutor();
Callable<String> callable = () -> {
        linearizeService.LinearizePDf(in, out);
        return "Task ended";
};
Future<String> future = executorService.submit(callable);
String result = future.get();
executorService.shutdown();
FileSystemResource pdfFile = new FileSystemResource(out);
return ResponseEntity
            .ok()
            .contentLength(pdfFile.contentLength())
            .contentType(
                    MediaType.parseMediaType("application/pdf"))
            .body(new ByteArrayResource(IOUtils.toByteArray(pdfFile.getInputStream())));

}

等到用Java创建文件

1 个答案: