Clarification on websocket

Question

我现在正在探索Websocket。我需要一些澄清。我使用websocket与tomcat。

tomcat如何映射websocket请求到特定的java类。例如，我们可以在web.xml中提供servlet类。但是它是如何为websocket工作的呢?

Answer 1

1- Javascript:为websocket声明如下变量:var websocket;var address = "ws://localhost:8080/appName/MyServ";

注意，appName是你的应用程序名称，MyServ是端点

也在脚本中添加一个函数来打开连接:

var websocket;
var address = "ws://localhost:8080/appName/MyServ";
function openWS() {
    websocket = new WebSocket(address);
    websocket.onopen = function(evt) {
        onOpen(evt) 
    };
    websocket.onmessage = function(evt) {
        onMessage(evt)
    };
    websocket.onerror = function(evt) {
        onError(evt)
    };
    websocket.onclose = function(evt) {
        onClose(evt)
    };
}
function onOpen(evt) {
   // what will happen after opening the websocket
}
function onClose(evt) {
    alert("closed")   
}
function onMessage(evt) {
    // what do you want to do when the client receive the message?
   alert(evt.data);
}
function onError(evt) {
   alert("err!")
}
function SendIt(message) {
// call this function to send a msg
    websocket.send(message);
}

2-在服务器端，您需要一个ServerEndpoint:我在上面的脚本中将其称为myServ。

现在，我认为这正是你所需要的:

通过注释@ServerEndpoint来声明任何Java POJO类WebSocket服务器端点

import java.io.IOException
import javax.servlet.ServletContext;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
@ServerEndpoint(value="/MyServ") 
public class MyServ{
    @OnMessage
    public void onMessage(Session session, String msg) throws IOException { 
        // todo when client send msg
        // tell the client that you received the message!
       try {
            session.getBasicRemote().sendText("I got your message :"+ msg);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

    }
    @OnOpen
    public void onOpen (Session session) {
      // tell the client the connection is open!
     try {
            session.getBasicRemote().sendText("it is open!");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
    @OnClose
    public void onClose (Session session) {
        System.out.println("websocket closed");
    }
    @OnError
    public void onError (Session session){ 
    }
}