Java 弹簧座-正在下载损坏/空白文件
我正在尝试创建一个端点来呈现/服务PDF文件。 我已经通过以下链接构建了API,但仍然面临一些问题 以下是我的代码:Java 弹簧座-正在下载损坏/空白文件,java,spring,spring-boot,postman,Java,Spring,Spring Boot,Postman,我正在尝试创建一个端点来呈现/服务PDF文件。 我已经通过以下链接构建了API,但仍然面临一些问题 以下是我的代码: byte[] targetArray = null; InputStream is = null; InputStream objectData = object.getObjectContent(); BufferedReader reader = new BufferedReader(new InputStreamReader(objectData)); char
byte[] targetArray = null;
InputStream is = null;
InputStream objectData = object.getObjectContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(objectData));
char[] charArray = new char[8 * 1024];
StringBuilder builder = new StringBuilder();
int numCharsRead;
while ((numCharsRead = reader.read(charArray, 0, charArray.length)) != -1) {
builder.append(charArray, 0, numCharsRead);
}
reader.close();
objectData.close();
object.close();
targetArray = builder.toString().getBytes();
is = new ByteArrayInputStream(targetArray);
return ResponseEntity.ok().contentLength(targetArray.length).contentType(MediaType.APPLICATION_PDF)
.cacheControl(CacheControl.noCache()).header("Content-Disposition", "attachment; filename=" + "testing.pdf")
.body(new InputStreamResource(is));
当我使用postman访问API时,我可以下载PDF文件,但问题是它完全是空白的。可能有什么问题?您可以尝试使用apache commons IOUtils。为什么要重新发明轮子:) 1.打开到远程服务器的连接 2.将inputStream复制到目标文件outputStream
public void downloadFileFromRemoteLocation(String serverlocation, File destinationFile) throws IOException
{
try (FileOutputStream fos = new FileOutputStream( destinationFile )){
URL url = new URL(serverlocation);
URLConnection connection = url.openConnection();
IOUtils.copy( connection.getInputStream(), fos);
}
}
如果您只想使用Java,请查看下面的代码片段
try {
// Get the directory and iterate them to get file by file...
File file = new File(fileName);
if (!file.exists()) {
context.addMessage(new ErrorMessage("msg.file.notdownloaded"));
context.setForwardName("failure");
} else {
response.setContentType("APPLICATION/DOWNLOAD");
response.setHeader("Content-Disposition", "attachment"+
"filename=" + file.getName());
stream = new FileInputStream(file);
response.setContentLength(stream.available());
OutputStream os = response.getOutputStream();
os.close();
response.flushBuffer();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (stream != null) {
try {
stream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
从服务器下载文件有多种方法,您可以使用
ResponseEntity
,HttpServletResponse
。以下是两种下载方法
@GetMapping("/download1")
public ResponseEntity<InputStreamResource> downloadFile1() throws IOException {
File file = new File(FILE_PATH);
InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
return ResponseEntity.ok()
.header(HttpHeaders.CONTENT_DISPOSITION,
"attachment;filename=" + file.getName())
.contentType(MediaType.APPLICATION_PDF).contentLength(file.length())
.body(resource);
}
嗯。。。为什么要将PDF读入
字符数组
,将其转换为字符串
,然后从字符串中提取字节?您确实了解字符数据和二进制数据之间的区别,对吗?另外,由于您的数据已经有了InputStream
,为什么不像您提到的第一个链接中那样使用InputStreamResource
?实际上,我正在尝试从一个远程位置获取PDF文件的内容,该位置正在流式传输我的PDF文件内容。这很公平,但由于您使用InputStream
对其进行操作,这对您来说应该是透明的。直接返回InputStreamResource
包装objectData
时会发生什么情况?为什么您觉得需要所有中间步骤?实际上InputStream是S3ObjectInputStream
。
@RequestMapping(value = "downloadFile", method = RequestMethod.GET)
public StreamingResponseBody getSteamingFile(HttpServletResponse response) throws IOException {
response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "attachment; filename=\"demo.pdf\"");
InputStream inputStream = new FileInputStream(new File("C:\\demo-file.pdf"));
return outputStream -> {
int nRead;
byte[] data = new byte[1024];
while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
System.out.println("Writing some bytes..");
outputStream.write(data, 0, nRead);
}
};
}