Directory
1. Export the required classes and interfaces
2. Define the MySQLBinlogListener class
3. Private method to start the reconnection timer
4. Complete code
Write a listener for real-time changes to the MySQL database.
Why write this listener: In order to monitor and respond to change events in the MySQL database in real time
- Real-time data synchronization: By monitoring MySQL Binlog, database change operations, such as insert, update, delete, etc., can be captured, so that data changes can be obtained in real time. This is very important for application scenarios that require timely data synchronization, such as real-time analysis, data synchronization, etc.
- Database monitoring and auditing: By listening to database change events, real-time monitoring and auditing functions of the database can be realized. You can capture and record every operation in the database, understand the changes in the database, and facilitate troubleshooting and security auditing.
- Data change triggers business logic: When the data in the database changes, the corresponding business logic can be triggered through the listener. For example, when a table changes, you can send notifications, call other services, or perform data processing and other operations.
- Data caching and updating: By listening to database change events, the cached data in the application can be updated in time to improve the performance and response speed of the application. When the database data changes, the cache can be automatically refreshed through the listener to ensure that the data used by the application is up-to-date.
In short: Writing such a listener can provide multiple benefits such as real-time data synchronization, database monitoring and auditing, business logic triggering, data cache update, and heterogeneous data integration.
Then we start to write a function like this:
1. Export required classes and interfaces
import com.github.shyiko.mysql.binlog.BinaryLogClient; import com.github.shyiko.mysql.binlog.event.*; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext; import org.springframework.stereotype.Component; import java.io.IOException; import java.util.Timer; import java.util.TimerTask;
Next, use a Spring component tag
@Component
2. Define the MySQLBinlogListener class
public class MySQLBinlogListener {
Define a constant to indicate that the reconnection interval is defined, and the unit can be set to milliseconds.
private static final int RECONNECT_INTERVAL = 10000;
Define a scheduled task for timing to try to reconnect to the MySQL server
private static Timer reconnectTimer;
Define a BinaryLogClient object for connecting to the MySQL server
private static BinaryLogClient client;
Define an ApplicationContext object for dependency injection
@Autowired private static ApplicationContext applicationContext;
Edit the entry method of the program, it will call the startMySQLBinlogListener method to start listening to MySQL Binlog events
public void main(String[] args) {
startMySQLBinlogListener();
}
This is the startMySQLBinlogListener method, which is used to start the MySQL Binlog listener
public static void startMySQLBinlogListener() {
Create a BinaryLogClient object, specify the host name, port number, database name, user name and password of the MySQL server.
client = new BinaryLogClient("127.0.0.1",3306, "your database table", "root", "password");
Set some properties of the BinaryLogClient object, including keep-alive, heartbeat packet sending interval, and heartbeat packet connection timeout.
client.setKeepAlive(true); client.setKeepAliveInterval(60 * 1000); client.setKeepAliveConnectTimeout(5 * 1000);
Register event listeners to respond to different types of events. Here, we process events of type TableMapEventData, send WebSocket messages according to table names; output logs for events of type UpdateRowsEventData, WriteRowsEventData, and DeleteRowsEventData.
client.registerEventListener(event -> {
try {
EventData data = event. getData();
if (data instanceof TableMapEventData) {
TableMapEventData tableMapEventData = (TableMapEventData) data;
String database = tableMapEventData.getDatabase();
String table = tableMapEventData.getTable();
WebsocketService websocketService = new WebsocketService();
if ("your database table".equalsIgnoreCase(table)) {
websocketService.groupSending("your database table field");
}
if ("your database table".equalsIgnoreCase(table)) {
websocketService.groupSending("your database table field");
}
} else if (data instance of UpdateRowsEventData) {
System.out.println("Update:");
System.out.println(data.toString());
} else if (data instanceof WriteRowsEventData) {
System.out.println("Add:");
System.out.println(data.toString());
} else if (data instanceof DeleteRowsEventData) {
System.out.println("Delete:");
System.out.println(data.toString());
}
} catch (Exception e) {
e.printStackTrace();
}
});
Register a lifecycle listener to handle connection success, communication exception, event data parsing exception, connection disconnection, etc.
client.registerLifecycleListener(new BinaryLogClient.LifecycleListener() {
@Override
public void onConnect(BinaryLogClient client) {
System.out.println("MySQL database is connected!");
}
@Override
public void onCommunicationFailure(BinaryLogClient client, Exception ex) {
System.out.println("The communication failure method has been executed!");
ex. printStackTrace();
}
@Override
public void onEventDeserializationFailure(BinaryLogClient client, Exception ex) {
System.out.println("The anti-quality method has been executed!");
ex. printStackTrace();
}
@Override
public void onDisconnect(BinaryLogClient client) {
System.out.println("MySQL database has been disconnected!");
startReconnectTimer();
}
});
3. Private method, start reconnection timer
The function is as follows:
private static void startReconnectTimer() {
If a reconnection timer already exists, cancel the previous scheduled task first
if (reconnectTimer != null) {
reconnectTimer. cancel();
}
Create a new reconnection timer and execute the scheduled task. The timed task will try to reconnect to the MySQL server
reconnectTimer = new Timer();
reconnectTimer.schedule(new TimerTask() {
@Override
public void run() {
boolean isConnected = client != null & & client.isConnected();
try {
if (isConnected) {
System.out.println("Disconnect from the database. Reconnect...");
client. disconnect();
}
client. connect();
} catch (IOException e) {
e.printStackTrace();
startReconnectTimer();
}
}
}, RECONNECT_INTERVAL);
}
This is the explanation of the whole code, which implements a MySQL Binlog listener, which can monitor the change events of the MySQL database and handle them accordingly.
4, complete code
Need to chat privately. . . . . .
The knowledge points of the article match the official knowledge files, and you can further learn relevant knowledge. Java skill treeHomepageOverview 118915 people are studying systematically