Java connecting with EMQ to realize publish and subscribe

isWulongbo 2020-11-10 18:04:48
java connecting emq realize publish

1. Open ports

EMQ X Provided by default 5 individual Listener, They will take up the following ports :

port explain
1883 MQTT/TCP Protocol port
11883 MQTT/TCP Protocol internal port , For native client connections only
8883 MQTT/SSL Protocol port
8083 MQTT/WS Protocol port
8084 MQTT/WSS Protocol port

ECS can be released on the security group port
 ECS port release
Or enter the command to open the corresponding port number
firewall-cmd --zone=public --add-port=1883-11883/tcp --permanent // permanent
firewall-cmd --zone=public --add-port=1883-11883/tcp // temporary
firewall-cmd --zone=public --add-port=1883/tcp --permanent // Permanent opening 1883 port
firewall-cmd --zone=public --remove-port=1883/tcp --permanent // Permanent ban 1883 port
firewall-cmd --reload // Reload the firewall without changing state -- Configuration takes effect immediately

notes : If you use the pagoda, remember not to forget that the pagoda also needs port clearance

2. download MqttSDK

MqttSDK Download link :MqttSDK
Download and unzip and import into idea in
 Directory structure
Core abstract classes :MessageHandler, use final modification ServerMqttClient Improve code security .

3. Sign in EMQ X Administrative console

Use the browser to open the address http:// The server ip:18083 , To log in, enter the default user name admin With default password public , Log in Dashboard
You can see that there is no client connected at this time

4. Publish subscriptions to messages

perform main Method , Look again Dashboard client , At this point, you can see that a user is connected 【 notes : because EMQ Login authentication is not configured , All users can connect to anonymous login 】
 perform main Method
java Connect emq
Click on the console WebSocket, Subscribe to topics emq,QoS(0: At most one transmission /1: At least one transmission /2: Only one transmission ), Here, in order to ensure that the news will reach , We choose QoS=2
 Console WebSocket
Modify the code : The subject of subscription is java, Release message The theme of emq, perform main After the method, at the same time Dashboard Click publish subscribe , You can see the log printed by the console , And the topic message received by the console
thus java Connect EMQ, And simulate the publication and subscription of topic messages OK 了 !
【 Reference documents 】EMQ The website links :EMQ Official website
Return to upper level [Centos8.0-EMQ The construction and deployment of ]:Centos8.0-EMQ The construction and deployment of
Go back to the next level [EMQ Data persistence ]


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