案发现场

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

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_221]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_221]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_221]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_221]
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:342) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2188) ~[mysql-connector-java-5.1.46.jar:5.1.46]

原因分析

原因一:MySQL服务未启动

解决方案

原因一解决方案:启动MySQL服务