[英]How to return a file to download in Java using Undertow?
I am trying to allow my game client to download the cache needed for the client to run.我试图让我的游戏客户端下载客户端运行所需的缓存。 Inside of my game web server I am doing this:
在我的游戏网络服务器内部,我正在这样做:
@RouteManifest(template="/cache", method="GET")
public class APICacheRoute extends RouteHttpHandler<JadePreprocessor> {
@Override
public void handleRequest(HttpServerExchange exchange) throws Exception {
Path path = Paths.get("./cache/Alterscape.zip");
File file = path.toFile();
exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "application/octet-stream");
exchange.getResponseSender().send(file);
}
}
However, I am receiving the error that the file must be a ByteBuffer.但是,我收到文件必须是 ByteBuffer 的错误。 How can I return a file to download?
如何返回要下载的文件?
My web server looks like this:我的网络服务器看起来像这样:
public static void initialize() {
ServerController server = new ServerController("localhost", 8080, 8443);
server.register(new APIVirtualHost());
server.inititialize();
}
My APIVirtualHost looks like this:我的 APIVirtualHost 看起来像这样:
public APIVirtualHost() {
super(127.0.0.1);
setDirectoryListingEnabled(false);
}
With Undertow, you need to dispatch the handler off the I/O thread to use a blocking operation.使用 Undertow,您需要从 I/O 线程分派处理程序以使用阻塞操作。 You'll need to do this any time you need to perform blocking operations, such as reading the a request body, accepting a file upload stream, and of course, sending a file.
您需要在需要执行阻塞操作时执行此操作,例如读取请求正文、接受文件上传流,当然还有发送文件。
At the top of your handle() method, use this to dispatch the request to a blocking thread, and off the non-blocking I/O thread:在 handle() 方法的顶部,使用它来将请求分派到阻塞线程,并关闭非阻塞 I/O 线程:
if (serverExchange.isInIoThread()) {
serverExchange.dispatch(this);
return;
}
Then start blocking when you're ready to send the buffer:然后在您准备好发送缓冲区时开始阻塞:
serverExchange.startBlocking();
Then to send a file, you can use a Buffered stream:然后要发送文件,您可以使用缓冲流:
serverExchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "application/octet-stream");
final File file = new File("/location/to/your/file");
final OutputStream outputStream = serverExchange.getOutputStream();
final InputStream inputStream = new FileInputStream(file);
byte[] buf = new byte[8192];
int c;
while ((c = inputStream.read(buf, 0, buf.length)) > 0) {
outputStream.write(buf, 0, c);
outputStream.flush();
}
outputStream.close();
inputStream.close();
The send
method on the ServerExchange
object is for sending response data using the non-blocking method - good for text or JSON. ServerExchange
对象上的send
方法用于使用非阻塞方法发送响应数据 - 适用于文本或 JSON。 The ByteBuffer
argument overload is for sending raw byte data, which is what Undertow converts strings to when sending. ByteBuffer
参数重载用于发送原始字节数据,这是 Undertow 在发送时将字符串转换为的内容。 It can be a bit misleading.这可能有点误导。
Happy Coding.快乐编码。
Try to wrap your own handler with this io.undertow.server.handlers.BlockingHandler
.尝试用这个
io.undertow.server.handlers.BlockingHandler
包装你自己的处理程序。 It already contains the necessary checks before performing a blocking operation.在执行阻塞操作之前,它已经包含了必要的检查。
public final class BlockingHandler implements HttpHandler {
...
@Override
public void handleRequest(final HttpServerExchange exchange) throws Exception {
exchange.startBlocking();
if (exchange.isInIoThread()) {
exchange.dispatch(handler);
} else {
handler.handleRequest(exchange);
}
}
...
}
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