警告: Could not obtain connection metadata

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 575 milliseconds ago.  The last packet sent successfully to the server was 538 milliseconds ago.

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)

at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)

at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.Util.handleNewInstance(Util.java:425)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:201)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.MysqlIO.negotiateSSLConnection(MysqlIO.java:4914)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1663)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1224)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2199)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2230)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2025)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:778)

at mysql.connector.java@5.1.47-bin/com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)

at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)