小编典典
我有一个针对Oracle的解决方案。自从甲骨文购买了Java以来，你不需要创建自己的应用程序，因此它发布了一个监听器。据我所知，这在内部不使用轮询，而是将通知推送到Java端(可能基于某些触发器)：
public interface oracle.jdbc.dcn.DatabaseChangeListener
extends java.util.EventListener {
void onDatabaseChangeNotification(oracle.jdbc.dcn.DatabaseChangeEvent arg0);
}
你可以像这样实现它(这只是一个示例)：
public class DBListener implements DatabaseChangeListener {
private DbChangeNotification toNotify;
public BNSDBListener(DbChangeNotification toNotify) {
this.toNotify = toNotify;
}
@Override
public void onDatabaseChangeNotification(oracle.jdbc.dcn.DatabaseChangeEvent e) {
synchronized( toNotify ) {
try {
toNotify.notifyDBChangeEvent(e); //do sth
} catch (Exception ex) {
Util.logMessage(CLASSNAME, "onDatabaseChangeNotification",
"Errors on the notifying object.", true);
Util.printStackTrace(ex);
Util.systemExit();
}
}
}
}
编辑：
你可以使用以下类进行注册：oracle.jdbc.OracleConnectionWrapper
public class oracle.jdbc.OracleConnectionWrapper implements oracle.jdbc.OracleConnection {...}
假设你在某处创建方法：
public void registerPushNotification(String sql) {
oracle.jdbc.driver.OracleConnection oracleConnection = ...;//connect to db
dbProperties.setProperty(OracleConnection.DCN_NOTIFY_ROWIDS, "true");
dbProperties.setProperty(OracleConnection.DCN_QUERY_CHANGE_NOTIFICATION, "true");
//this is what does the actual registering on the db end
oracle.jdbc.dcn.DatabaseChangeRegistration dbChangeRegistration= oracleConnection.registerDatabaseChangeNotification(dbProperties);
//now you can add the listener created before my EDIT
listener = new DBListener(this);
dbChangeRegistration.addListener(listener);
//now you need to add whatever tables you want to monitor
Statement stmt = oracleConnection.createStatement();
//associate the statement with the registration:
((OracleStatement) stmt).setDatabaseChangeRegistration(dbChangeRegistration); //look up the documentation to this method [http://docs.oracle.com/cd/E11882_01/appdev.112/e13995/oracle/jdbc/OracleStatement.html#setDatabaseChangeRegistration_oracle_jdbc_dcn_DatabaseChangeRegistration_]
ResultSet rs = stmt.executeQuery(sql); //you have to execute the query to link it to the statement for it to be monitored
while (rs.next()) { ...do sth with the results if interested... }
//see what tables are being monitored
String[] tableNames = dbChangeRegistration.getTables();
for (int i = 0; i < tableNames.length; i++) {
System.out.println(tableNames[i] + " has been registered.");
}
rs.close();
stmt.close();
}
此示例不包括try-catch子句或任何异常处理。
2020-03-12