Set up websockets with Jetty 11

Question

我正试图从Jetty 9.4迁移到Jetty 11(可能太早了？(，但未能调整用于设置websocket的代码。我在9.4中实现这一点的方式如下：

Server server = new Server();
HttpConfiguration httpConfig = new HttpConfiguration();
httpConfig.setSendServerVersion(false);
HttpConnectionFactory httpFactory = new HttpConnectionFactory(httpConfig);
ServerConnector httpConnector = new ServerConnector(server, httpFactory);
httpConnector.setPort(port);
server.setConnectors(new Connector[] { httpConnector });
// Setup the basic application "context" for this application at "/"
// This is also known as the handler tree (in jetty speak)
ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
context.setContextPath("/");
// Add a websocket to a specific path spec
ServletHolder holderEvents2 = new ServletHolder("websocket", EventsServlet.class);
context.addServlet(holderEvents2, "/events/*");
HandlerList handlers = new HandlerList();
handlers.setHandlers(new Handler[] { context, new DefaultHandler() });
server.setHandler(handlers);
public class EventsServlet extends WebSocketServlet {
@Override
public void configure(WebSocketServletFactory factory) {
// register a socket class as default
factory.register(EchoSocket.class);
}
}
public class EchoSocket implements WebSocketListener {
// ...
}

由于已经没有WebSocketServlet类了，我花了一些时间找到了JettyWebSocketServlet类。根据它的JavaDoc，我认为它应该如下所示：

public class EventsServlet extends JettyWebSocketServlet {
@Override
protected void configure(JettyWebSocketServletFactory factory) {
// register a socket class as default
//      factory.register(EchoSocket.class);
factory.addMapping("/", (req,res)->new EchoSocket());
}
}

但带有addMapping的行实际上从未执行过。此外，JettyWebSocketServlet工厂没有JettyWebSSocketServlet的JavaDoc建议的名为setDefaultMaxFrameSize的方法。

我在网上能找到的似乎都是Jetty<=9.4，甚至https://github.com/jetty-project/embedded-jetty-websocket-examples。

如有任何帮助，我们将不胜感激。

Answer 1

我也遇到了类似的问题，尽管我在Jetty 9.4下运行的版本与您的版本有点不同，使用的是WebSocketHandler而不是WebSocketServlet。我在使用旧方法时遇到了一些问题，因为在Jetty 9.4下，我必须将侦听器类作为Class对象传递，这使得依赖注入变得很痛苦。

不过，我现在已经在Jetty 11.0.0下完成了这项工作。几天前，当我试图在Jetty 11中解决这个问题时，我发现了你的问题，这激发了我真正做到这一点，所以谢谢！

FWIW，我的Jetty 9.4版本(用于一个琐碎的测试(看起来是这样的：

public static void main(String[] argv) throws Exception
{
int serverPort = Integer.getInteger("server.port", 8080);
Server server = new Server(serverPort);
ContextHandlerCollection handlers = new ContextHandlerCollection();
WebSocketHandler wsh = new WebSocketHandler.Simple (TestWebSocketListener.class);
handlers.addHandler(createContextHandler("/ws", wsh));
ResourceHandler rh = new ResourceHandler();
rh.setDirectoriesListed(false);
rh.setBaseResource(Resource.newClassPathResource("/WEB-STATIC/"));
handlers.addHandler(createContextHandler("/", rh));
server.setHandler(handlers);
server.start();
server.join();
}
// Convenience method to create and configure a ContextHandler.
private static ContextHandler createContextHandler(String contextPath, Handler wrappedHandler)
{
ContextHandler ch = new ContextHandler (contextPath);
ch.setHandler(wrappedHandler);
ch.clearAliasChecks();
ch.setAllowNullPathInfo(true);
return ch;
}

这里，TestWebSocketListener是WebSocketListener的一个微不足道的实现，它只实现每个侦听器方法并将参数打印到System.err。(我确实说过这是一个微不足道的测试。(我还在onWebSocketText回调中向客户端发回一条消息，只是为了检查这是否有效。

我在这里没有使用DefaultHandler，而是显式地创建了一个ResourceHandler，它从类路径中存储的资源树(在/WEB-STATIC/前缀下(中提供一些简单的静态资源。

我在Jetty 11.0.0下工作的版本只是将上面的main方法更改为：

public static void main(String[] argv) throws Exception
{
int serverPort = Integer.getInteger("server.port", 8080);
Server server = new Server(serverPort);
ContextHandlerCollection handlers = new ContextHandlerCollection();
ResourceHandler rh = new ResourceHandler();
rh.setDirectoriesListed(false);
rh.setBaseResource(Resource.newClassPathResource("/WEB-STATIC/"));
handlers.addHandler(createContextHandler("/", rh));
Servlet websocketServlet = new JettyWebSocketServlet() {
@Override protected void configure(JettyWebSocketServletFactory factory) {
factory.addMapping("/", (req, res) -> new TestWebSocketListener());
}
};
ServletContextHandler servletContextHandler = new ServletContextHandler();
servletContextHandler.addServlet(new ServletHolder(websocketServlet), "/ws");
JettyWebSocketServletContainerInitializer.configure(servletContextHandler, null);
handlers.addHandler(servletContextHandler);
server.setHandler(handlers);
server.start();
server.join();
}

对JettyWebSocketServletContainerInitializer.configure的调用很重要：如果没有调用，我会收到异常，抱怨WebSocket组件没有初始化。

需要注意的一点是，这两个处理程序的顺序已经更改——之前，WebSocketHandler是在ResourceHandler之前添加的。然而，当使用ServletContextHandler时，这是为本应由ResourceHandler处理的路径返回404，所以我交换了顺序。

TestWebSocketListener在两个版本之间是相同的。显然，现在我控制了构造函数调用，添加依赖注入对我来说容易多了！

我必须更改的另一件事是我提取的Maven工件的名称。websocket-server工件似乎不再存在于Jetty 11中，所以我更改了这个：

<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-server</artifactId>
<version>9.4.35.v20201120</version>
</dependency>
<dependency>
<groupId>org.eclipse.jetty.websocket</groupId>
<artifactId>websocket-server</artifactId>
<version>9.4.35.v20201120</version>
</dependency>

到此：

<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-server</artifactId>
<version>11.0.0</version>
</dependency>
<dependency>
<groupId>org.eclipse.jetty.websocket</groupId>
<artifactId>websocket-jetty-server</artifactId>
<version>11.0.0</version>
</dependency>

Answer 2

多亏了mdf的详细解释，我才得以修复代码。最后，我只需要更换

ServletHolder holderEvents = new ServletHolder("websocket", EventsServlet.class);
context.addServlet(holderEvents, "/events/*");

带有

Servlet websocketServlet = new JettyWebSocketServlet() {
@Override
protected void configure(JettyWebSocketServletFactory factory) {
factory.addMapping("/", (req, res) -> new EchoSocket());
}
};
context.addServlet(new ServletHolder(websocketServlet), "/events/*");
JettyWebSocketServletContainerInitializer.configure(context, null);

有了这个，我还可以去掉EventsServlet类。

Answer 3

您可以在Jetty 11中找到信息https://github.com/jetty-project/embedded-jetty-websocket-examples/blob/11.0.x/native-jetty-websocket-example/src/main/java/org/eclipse/jetty/demo/EventServer.java

从9号码头升级，包括以下包

1. org.eclipse.jetty:jetty-server:11.0.0
2. org.eclipse.jetty:jetty-servlet:11.0.0
3. org.eclipse.jetty:jetty-annotations:11.0.0
4. org.eclipse.jetty.websocket:websocket-jetty-server:11.0.0
5. org.eclipse.jetty.websocket:websocket-jetty-client:11.0.0

请注意，websocket-client和websocket-server的名称已更改为websocket-jetty-client和websocket-jetty-server

如@mdf所指出的，JettyWebSocketServletContainerInitializer.configure能够消除以下消息：

WebSocketComponents尚未创建

现在我的应用程序可以与jetty 11配合使用。

这是我的WebsocketServlet

import org.eclipse.jetty.websocket.server.JettyWebSocketServlet;
import org.eclipse.jetty.websocket.server.JettyWebSocketServletFactory;
public class KernelServlet extends JettyWebSocketServlet {
@Override
public void configure(JettyWebSocketServletFactory factory) {
factory.register(KernelHandler.class);
}
}

这是服务器初始化代码

Server server = new Server(port);
ServletContextHandler contextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS);
contextHandler.setContextPath("/");
contextHandler.addServlet(WebClientServlet.class, "/client");
contextHandler.addServlet(KernelServlet.class, "/kernel");
JettyWebSocketServletContainerInitializer.configure(contextHandler, null);
try {
server.setHandler(contextHandler);
server.start();
server.join();
} catch (Exception e) {
e.printStackTrace();
}