Same as every HTTP server framewords, EzyHttp allows you download file, too. And we recommend you use asynchronous API, to know why, please take a look the explanation here.

1. ResourceRequestHandler

EzyHTTP provides to you an convenient FileUploader class. It uses ResourceDownloadManager, an event loop like below:

And the event loop will do like this:

loop:
    take a outputstream/file inputstream pair from the queue:
        take 1024 bytes from the file inputstream of the requested file and push to client's outputstream
        if there is no remain data in the file inputstream
            then response to the client: call to the callback and done
        else
            push the the inputstream/outputstream pair back to the queue

2. Enable file download configuration

To enable file download, you can add the configuration to your application.properties file like this:

resources.enable=true

If you want to set queue capacity and thread pool size, buffer size, you can setup:

resources.download.capacity=[an integer value]
resources.download.thread_pool_size=[an integer value]
resources.download.buffer_size=[an integer value]

3. Download file asynchronously

To download a file asynchronously with ResourceRequestHandler, you can do like this:

    @Controller("/api/v1")
    @AllArgsConstructor
    public class FileController {
        private final FileDownloadService fileDownloadService;
        @Async
        @DoGet("/files/{file}")
        public void downloadGet(
            RequestArguments requestArguments,
            @PathVariable("file") String file,
            @RequestHeader("token") String token
        ) throws Exception {
            if (EzyStrings.isBlank(token)) {
                throw new HttpBadRequestException("token can not be null");
            }
            fileDownloadService.download(requestArguments, file);
        }
    }
    @EzySingleton
    @AllArgsConstructor
    public class FileDownloadService {
        private final ResourceDownloadManager resourceDownloadManager;
        public void download(
            RequestArguments requestArguments,
            String file
        ) throws Exception {
            ResourceRequestHandler handler = new ResourceRequestHandler(
                "files/" + file,
                "files/" + file,
                EzyFileUtil.getFileExtension(file),
                resourceDownloadManager
            );
            handler.handle(requestArguments);
        }
    }

4. Download file Synchronously

To download a file synchronously, you can do like this:

    @Controller("/api/v1")
    @AllArgsConstructor
    public class FileController {
        @DoGet("/files/{file}")
        public ResponseEntity downloadGet(
            HttpServletResponse response,
            @PathVariable("file") String file
        ) throws Exception {
            try (InputStream inputStream = new FileInputStream(file)) {
                OutputStream outputStream = response.getOutputStream();
                byte[] buffer = new byte[1024];
                while (true) {
                    int read = inputStream.read(buffer);
                    if (read > 0) {
                        outputStream.write(buffer, 0, read);
                    } else {
                        break;
                    }
                }
            }
            return ResponseEntity.noContent();
        }
    }

Next step

You can see how to create a website.

EzyHTTP Download File

1. ResourceRequestHandler

2. Enable file download configuration

3. Download file asynchronously

4. Download file Synchronously

Next step