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在JavaScript中使用mqtt.js的详细过程

作者:ice_bear221

这篇文章主要介绍了在JavaScript中使用mqtt.js的相关知识,本文给大家介绍的非常详细,对大家的学习或工作具有一定的参考借鉴价值,需要的朋友可以参考下

ActiveMQ使用(二):在JavaScript中使用mqtt.js

1. 环境准备 jQuery-1.10

下载地址:https://www.jsdelivr.com/package/npm/jquery-1.10.2?tab=filesmqtt.js 4.3.7:
下载地址:https://www.jsdelivr.com/package/npm/mqtt

2. 相关代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div class="connect-input-box">
        <label for="host">host:</label>
        <input type="text" name="host" placeholder="input host" value="127.0.0.1"><br>
        <label for="port">port:</label>
        <input type="text" name="port" placeholder="input port" value="61614"><br>
        <label for="clientId">client id:</label>
        <input type="text" name="clientId" placeholder="input client id"><br>
        <label for="userId">user id:</label>
        <input type="text" name="userId" placeholder="input user id" value="user"><br>
        <label for="password">password:</label>
        <input type="text" name="password" placeholder="input password" value="pass"><br>
        <label for="destination">destination:</label>
        <input type="text" name="destination" placeholder="input destination" value="world"><br>
        <button id="connect" type="submit">connect</button>
        <button id="disconnect" type="submit">disconnect</button>
    </div>
    <div class="log-box">
        <p id="log-show"></p>
    </div>
    <div class="send-message-box">
        <label for="topic">topic:</label>
        <input type="text" name="topic"><br>
        <label for="queue">queue:</label>
        <input type="text" name="queue"><br>
        <input type="text" name="message"><br>
        <button id="send">send</button>
    </div>
    <div class="subscribe-box">
        <label for="subscribe-topic">subscribe-topic:</label>
        <input type="text" name="subscribe-topic">
        <button id="subscribe">subscribe</button>
    </div>
    <div class="unsubscribe-box">
        <label for="unsubscribe-topic"></label>
        <input type="text" name="unsubscribe-topic">
        <button id="unsubscribe">unsubscribe</button>
    </div>

    <script src="plugins/jquery-1.10.1.js"></script>
    <script src="plugins/mqtt.min.js"></script>
    <script type="module">

        $(() => {
            console.log('mqtt: ', mqtt)
            $('input[name="clientId"]').val("example-" + Math.floor(Math.random() * 10000))

            if (!window.WebSocket) {
                console.log('不支持WebSocket')
            } else {
                
            }
        })

        var client, destination

        $('#connect').click(() => {
            var host = $('input[name="host"]').val()
            var port = $('input[name="port"]').val()
            var clientId = $('input[name="clientId"]').val()
            var user = $('input[name="userId"]').val()
            var password = $('input[name="password"]').val()

            destination = $('input[name="destination"]').val()
            console.log(host)
            console.log(mqtt)

            // 创建一个client 实例
            let url = 'ws://' + host + ':' + port + '/mqtt'
            client = mqtt.connect(url)
            console.log(client)
            client.on('connect', onConnect)

            // 断开连接以后触发
            client.on('close', () => {
                console.log('disconnected')
            })

            // 收到断开连接的报文后触发
            client.on('disconnect', packet => {
                console.log(packet)
            })

            // 客户端下线时触发
            client.on('offline', () => {
                console.log('offline')
            })

            // 接收消息
            client.on('message', (topic, payload, packet) => {
                // message is buffer
                console.log(`Topic: ${topic}, Message: ${payload.toString()}, QoS: ${packet.qos}`)
            })
        })

        // 当client连接时调用
        function onConnect() {
            // 订阅主题
            client.subscribe('world', err => {
                if (!err) {
                    // 发布消息
                    client.publish('world', 'hello mqtt')
                }
            })
        }

        // 断开连接
        $('#disconnect').click(() => {
            console.log('disconnect');
            client.end()
        })

        // 发送消息
        $('#send').click(() => {
            console.log('send')
            let topic = $('input[name="topic"]').val()
            let payload = $('input[name="message"]').val()
            let options = {
                qos: 0,
                retain: false,
                properties: {
                    payloadFormatIndicator: true
                }
            }
            client.publish(topic.toString(), payload, options, (err) => {
                if (err) {
                    console.log(err)
                } else {
                    console.log('published')
                }
            })
        })

        // 订阅主题
        $('#subscribe').click(() => {
            console.log('subscribe')
            let topic = $('input[name="subscribe-topic"]').val()
            client.subscribe(topic, {qos: 0}, (error, granted) => {
                if (error) {
                    console.log(error)
                } else {
                    console.log(`${granted[0].topic} was subscribed`)
                }
            })
        })

        // 取消订阅主题
        $('#unsubscribe').click(() => {
            console.log('unsubscribe')
            let topic = $('input[name="unsubscribe-topic"]').val()
            client.unsubscribe(topic, err => {
                if (err) {
                    console.log(err)
                } else {
                    console.log('unscribed')
                }
            })
        })
    </script>
</body>
</html>

3. 结果展示

3.1 连接

3.2 订阅

3.3 发送消息

3.4 取消订阅

3.5 断开连接

4. 相关参考

JS HTML Web端使用MQTT通讯测试

MQTT.js 入门教程

https://www.jsdelivr.com/package/npm/mqtt

5. 注意

SprintBoot项目中集成ActiveMQ后,接收到的数据为字节数组
一种解决方式为:

@JmsListener(destination = "test_producer", containerFactory = "topicListenerContainer")
    public void receiveTestProducer(Message message) throws JMSException {
        String msg = StringUtils.activeMQMessageParse(message);
        System.out.println("收到测试生产者的消息: " + msg);
    }


public class StringUtils {

    /**
     * 将字符串进行分割并获得字节数组
     * @param str 待处理字符串
     * @param split 分割字符串
     * @return 字节数组
     */
    public static byte[] stringToBytes(String str, String split) {
        String[] strArr = str.split(split);
        byte[] byteArr = new byte[strArr.length];
        for (int i = 0; i < strArr.length; i++) {
            byteArr[i] = (byte) Integer.parseInt(strArr[i]);
        }
        return byteArr;
    }

    /**
     * 根据字节数组获取指定字符集的字符串
     * @param byteArr 字节数组
     * @param charset 编码字符集
     * @return 处理后的字符串
     */
    public static String bytesToString(byte[] byteArr, Charset charset) {
        return new String(byteArr, charset);
    }

    /**
     * 将字符串根据分隔符转成字节数组,然后转成指定字符集的字符串
     * @param str 待处理字符串
     * @param split 分割字符串
     * @param charset 指定字符集
     * @return 处理后的字符串
     */
    public static String stringToString(String str, String split, Charset charset) {
        return bytesToString(stringToBytes(str, split), charset);
    }

    /**
     * 将ActiveMQ接收到的消息转换为UTF-8字符串
     * @param message
     * @return
     */
    public static String activeMQMessageParse(Message message) {
        String str = null;
        if (message instanceof ActiveMQTextMessage) {
            ActiveMQTextMessage textMessage = (ActiveMQTextMessage) message;
            try {
                str = textMessage.getText().toString();
            } catch (JMSException e) {
                e.printStackTrace();
            }
//            System.out.println("text : " + textMessage.getText());
        } else if (message instanceof ActiveMQBytesMessage) {
            ActiveMQBytesMessage bytesMessage = (ActiveMQBytesMessage) message;
            byte[] byteArr = new byte[0];
            try {
                byteArr = new byte[(int) bytesMessage.getBodyLength()];
                int flag = bytesMessage.readBytes(byteArr);
                str = bytesToString(byteArr, StandardCharsets.UTF_8);
//                System.out.println("bytes : " + flag + " : " + str);
            } catch (JMSException e) {
                e.printStackTrace();
            }
        }
        return str;
    }
}

到此这篇关于在JavaScript中使用mqtt.js的文章就介绍到这了,更多相关js使用mqtt.js内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!

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