目前，如果我们托管在 Tomcat 上的 Spring 应用程序的数据库不可用，则上下文初始化失败并且所有请求都返回 404。
什么是克服这个问题的好方法？与其在下一个 Tomcat 之前应用程序不可用，我希望它在不可用时向用户显示错误消息，并在数据库可用时自动恢复（就像在 Tomcat 已经运行时发生数据库故障一样）。
我可以将所有 bean 设置为惰性初始化，但我不确定这是最好的解决方案吗？Tomcat不能每x秒/请求重试一次初始化并同时显示一个不错的错误页面吗？对此有什么想法吗？
DB不可用时启动时引发的错误示例：
Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy$LazyConnectionInvocationHandler.getTargetConnection(LazyConnectionDataSourceProxy.java:401)
at org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy$LazyConnectionInvocationHandler.invoke(LazyConnectionDataSourceProxy.java:376)
at com.sun.proxy.$Proxy43.getMetaData(Unknown Source)
at com.googlecode.flyway.core.dbsupport.DbSupportFactory.getDatabaseProductName(DbSupportFactory.java:103)
... 67 more
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
... 72 more
Mar 28, 2013 11:19:47 AM org.apache.catalina.core.StandardContext startInternal
SEVERE: Error listenerStart
Mar 28, 2013 11:19:47 AM org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [] startup failed due to previous errors