How to send a push to your phone based on whether the database has new content

This is what I am now:

User app through software feedback, the server receives the value, will put this value into the MySQL database inside.

Now, the Java server opens up an API that serves as a value for querying database feedback content.
An administrator-only app that displays the latest feedback when opened.

My needs are:
How to receive new feedback content, the administrator-specific app to pop up a push, rather than manually open the app to discover the value.

I want to understand this general idea and mechanism of operation.

Reply content:

This is what I am now:

User app through software feedback, the server receives the value, will put this value into the MySQL database inside.

Now, the Java server opens up an API that serves as a value for querying database feedback content.
An administrator-only app that displays the latest feedback when opened.

My needs are:
How to receive new feedback content, the administrator-specific app to pop up a push, rather than manually open the app to discover the value.

I want to understand this general idea and mechanism of operation.

Server push a message to the client

For Android, if the app is not in the foreground, it can be done via the service:

• Use Intentservice to crawl the server's latest data in the background;

• Use Alarmmanager and pendingintent to schedule the operation of services (interval between service queries);

• Use notification to notify the user from the background (the user can see the details after the drop-down notification bar, then click to enter the app).

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