Could not open JDBC Connection for transaction

org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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.)
Caused by: 
org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Communications link failure

在linux系统下部署项目，启动的时候就报这个错，在网上看了很多资料，有说hosts问题，有说配置文件问题，还有说连接池有问题，看了这么多也不知道改什么，希望大神能够指点指点。