我正在开发一个Spring MVC应用程序，用户可以在其中下载文件。用户可以点击触发下载机制的附件。Spring，Java：流式文件下载以避免内存不足错误

昨天，当该多个下载和两个具有约2 GB的文件，就引起一个内存不足错误(下面登录)。

为了避免这个问题，解决这个问题的一种方法似乎是在块流下载数据，并且只处理这些块在服务层，而不是整个文件。

不幸的是，我不知道如何继续前进，任何帮助都会很好。如果这个选项不能飞，关于如何解决这个问题的任何建议。

错误日志：

HTTP Status 500 - Handler processing failed; nested exception is java.lang.OutOfMemoryError: Direct buffer memory

type Exception report

message Handler processing failed; nested exception is java.lang.OutOfMemoryError: Direct buffer memory

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Handler processing failed; nested exception is java.lang.OutOfMemoryError: Direct buffer memory

org.springframework.web.servlet.DispatcherServlet.triggerAfterCompletionWithError(DispatcherServlet.java:1303)

org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:977)

org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)

org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)

org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858)

javax.servlet.http.HttpServlet.service(HttpServlet.java:620)

org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)

控制器代码：

@RequestMapping(value = "/download/attachment/{attachid}", method = RequestMethod.GET)

public void getAttachmentFromDatabase(@PathVariable("attachid") int attachid,

, HttpServletResponse response,) {

response.setContentType("application/octet-stream");

GroupAttachments groupAttachments = this.groupAttachmentsService.getAttachmenById(attachid);

response.setHeader("Content-Disposition", "attachment; filename=\"" + groupAttachments.getFileName() + "\"");

response.setContentLength(groupAttachments.getSendAttachment().length);

FileCopyUtils.copy(groupAttachments.getSendAttachment(), response.getOutputStream());

response.flushBuffer();

}

服务层：

@Override

public GroupAttachments getAttachmenById(int attachId) {

Person person = this.personService.getCurrentlyAuthenticatedUser();

GroupAttachments groupAttachments = this.groupAttachmentsDAO.getAttachmenById(attachId);

GroupMembers groupMembers = this.groupMembersService.returnMembersMatchingUsernameAccountId(person.getUsername(),

groupAttachments.getGroupId());

if (!(groupMembers == null)) {

if (person.getUsername().equals(groupMembers.getMemberUsername())) {

try {

Path path = Paths.get(msg + groupAttachments.getGroupId() + "/" +

groupAttachments.getFileIdentifier());

groupAttachments.setSendAttachment(Files.readAllBytes(path));

return groupAttachments;

} catch (IOException ignored) {

this.groupAttachmentsDAO.removeAttachment(attachId);

return null;

}

}

return null;

} else {

return null;

}

}

谢谢。 :-)

更新

新的下载机制：

控制器：

public ResponseEntity getAttachmentFromDatabase(@PathVariable("attachid") int attachid,

@PathVariable("groupaccountid") Long groupAccountId, @PathVariable("api") String api,

HttpServletResponse response,

@PathVariable("type") boolean type) {

Path path = this.groupAttachmentsService.getAttachmentPathById(attachid);

GroupAttachments groupAttachments = this.groupAttachmentsService.getAttachmentObjectOnlyById(attachid);

response.setContentType("application/octet-stream");

response.setHeader("Content-Disposition", "attachment; filename=\""+groupAttachments.getFileName()+"\"");

try {

OutputStream outputStream = response.getOutputStream();

Files.copy(path,outputStream);

outputStream.flush();

outputStream.close();

response.flushBuffer();

}

服务层：

@Override

public Path getAttachmentPathById(int attachId){

Person person = this.personService.getCurrentlyAuthenticatedUser();

GroupAttachments groupAttachments = this.groupAttachmentsDAO.getAttachmenById(attachId);

GroupMembers groupMembers = this.groupMembersService.returnMembersMatchingUsernameAccountId(person.getUsername(),

groupAttachments.getGroupId());

if (!(groupMembers == null)) {

if (person.getUsername().equals(groupMembers.getMemberUsername())) {

try {

return Paths.get(msg + groupAttachments.getGroupId() + "/" +

groupAttachments.getFileIdentifier());

} catch (Exception ignored) {

return null;

}

}

return null;

} else {

return null;

}

}

+1

您正在阅读的一切到内存中，不这样做......的'Files.readAllBytes'加载整个'2Gb'到内存中。根本不要。延迟加载，而不是首先加载它，逐个阅读并直接流式传输。改为使用'Files.copy(Path，OutputStream)'。 –

+0

复制将流式传输，而不是加载它。请阅读评论... –

+0

@ M.Deinum：抱歉误读。我已经更新了代码，并且用Files.copy(path，outputStream)尝试过，效果很好。我已经在主帖中发布了更新的代码，请你检查是否有可能的优化。谢谢。 –