在连接到AWS rds mysql实例时，出现以下错误。
仅当我在同一tomcat实例上部署两次不同的战争时，才会发生这种情况。这两个应用程序都连接到其相应的数据库实例（单独的数据库）。
如果我分别部署它们，则不会有问题。
这是错误：
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
27-Jul-2018 18:31:06.214 SEVERE [pool-27-thread-3] org.apache.tomcat.jdbc.pool.ConnectionPool.init Unable to create initial connections of pool.
com.mysql.cj.jdbc.exceptions.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 com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:741)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:57)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1663)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:662)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:352)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:221)
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:307)
at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:200)
at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:728)
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:662)
at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:480)
at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:154)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:115)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:102)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:126)
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:139)