[Java][WebSocket][Tyrus]JavaでWebSocketクライアントを作る

テスト用 WebSocket サーバーの作成

Node.js で簡単な WebSocket サーバーを用意します。

package.json

{
  "dependencies": {
    "ws": "^7.3.1"
  }
}

index.js

const ws = require("ws");
const server = new ws.Server({ port: 3000 });

server.on("connection", (ws) => {
  console.log("connected");

  server.clients.forEach((client) => {
    setInterval(() => {
      client.send(new Date().toString());
    }, 1000);
  });

  ws.on("message", (message) => {
    server.clients.forEach((client) => {
      client.send(message);
    });
  });

  ws.on("close", () => {
    console.log("close");
  });

  ws.on("error", (e) => {
    console.error(e);
  });
});

実行

$ node index.js

WebSocket クライアントの実装

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>example</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>example</name>

    <dependencies>
        <dependency>
            <groupId>org.glassfish.tyrus.bundles</groupId>
            <artifactId>tyrus-standalone-client</artifactId>
            <version>1.17</version>
        </dependency>
    </dependencies>

</project>

src/main/java/com/example/Example.java

package com.example;

import javax.websocket.*;
import java.io.IOException;
import java.net.URI;

public class Example {

    public static void main(String[] args) throws IOException, DeploymentException, InterruptedException {
        URI uri = URI.create("ws://localhost:3000");

        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
        Session session = container.connectToServer(WebSocketHandler.class, uri);

        RemoteEndpoint.Basic basic = session.getBasicRemote();
        basic.sendText("Hello");

        Thread.sleep(3000);

        session.close();
    }

}

src/main/java/com/example/WebSocketHandler.java

package com.example;

import javax.websocket.*;

@ClientEndpoint
public class WebSocketHandler {

    @OnError
    public void onError(Session session, Throwable cause) {
        System.err.println("error");
        cause.printStackTrace();
    }

    @OnMessage
    public void onMessage(String msg, Session session) {
        System.out.println("message: " + msg);
    }

    @OnClose
    public void onClose(Session session, CloseReason closeReason) {
        System.out.println("closed");
    }

    @OnOpen
    public void onOpen(Session session) {
        System.out.println("opened");
    }

}

実行

$ mvn -q -e compile exec:java -Dexec.mainClass=com.example.Example
opened
message: Hello
message: Wed Sep 30 2020 09:28:08 GMT+0900 (GMT+09:00)
message: Wed Sep 30 2020 09:28:09 GMT+0900 (GMT+09:00)
message: Wed Sep 30 2020 09:28:10 GMT+0900 (GMT+09:00)
closed