Connections could not be acquired from the underly

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
MLog initialization issue: slf4j found no binding or threatened to use its (dangerously silent) NOPLogger. We consider the slf4j library not found.
log4j:WARN No appenders could be found for logger (com.mchange.v2.log.MLog).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
java.sql.SQLException: Connections could not be acquired from the underlying database!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:118)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:690)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140)
at com.chinamworld.db.DBManager.insert(DBManager.java:60)
at Test.main(Test.java:28)
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:1463)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:639)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:549)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:756)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:683)

... 3 more

以上問題可能有一下緣由形成：

1，驅動配置有誤：driver=com.mysql.jdbc.Driver
2，數據庫鏈接地址有誤：url=jdbc:mysql://localhost:3306/test?3useUnicode=true&characterEncoding=utf8
3，密碼或賬號有誤：username=root
      password=root

4，數據庫未啓動或無權訪問

5，項目未引入對應的驅動jar包mysql-connector-java-5.1.6-bin.jar

6,mysql root沒有遠程訪問的權限，須要增長權限，增長權限的步驟以下：
進入mysql數據庫：
grant all privileges on *.* to 'root'@'%' identified by 'root' with grant option;
flush privileges;