具体错误信息：
严重: StandardWrapper.Throwable
org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is org.apache.commons.dbcp.SQLNestedException: Error preloading the connection pool
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:241)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:372)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:417)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:255)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:633)
at com.qujiu.base.service.XgPlatformManager$$EnhancerBySpringCGLIB$$112e244c.getPlarMark(<generated>)
at com.qujiu.base.web.init.BaseDataDictionary.init(BaseDataDictionary.java:40)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5210)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5493)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.commons.dbcp.SQLNestedException: Error preloading the connection pool
at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:868)
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540)
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:203)
... 20 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1014)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1104)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2412)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2445)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2230)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:813)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:37)
at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:290)
at org.apache.commons.pool.impl.GenericObjectPool.addObject(GenericObjectPool.java:996)
at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:865)
... 22 more
七月 30, 2014 12:04:20 下午 org.apache.catalina.core.StandardContext loadOnStartup
严重: Servlet /wowo-web threw load() exception
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1014)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1104)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2412)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2445)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2230)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:813)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:37)
at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:290)
at org.apache.commons.pool.impl.GenericObjectPool.addObject(GenericObjectPool.java:996)
at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:865)
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540)
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:203)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:372)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:417)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:255)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:633)
at com.qujiu.base.service.XgPlatformManager$$EnhancerBySpringCGLIB$$112e244c.getPlarMark(<generated>)
at com.qujiu.base.web.init.BaseDataDictionary.init(BaseDataDictionary.java:40)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5210)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5493)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
七月 30, 2014 12:04:20 下午 org.apache.catalina.core.ApplicationContext log
信息: Initializing Spring FrameworkServlet ‘springmvc‘
七月 30, 2014 12:04:21 下午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["http-bio-8080"]
七月 30, 2014 12:04:21 下午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["ajp-bio-8009"]
七月 30, 2014 12:04:21 下午 org.apache.catalina.startup.Catalina start
信息: Server startup in 18779 ms
问题分析：
查看MySQL的当前最大连接数，登录MySQL：mysql -uroot -p，回车；输入password，回车；
输入命令：select VARIABLE_VALUE from information_schema.GLOBAL_VARIABLES where VARIABLE_NAME=‘MAX_CONNECTIONS‘; 回车
显示当前最大连接数为：151，之前通过文章“CentOS下mysql最大连接数设置 1040 too many connection”中的方法设置为3600了，如今怎么又变成151了？原来这种方法仅仅是暂时的改动了最大连接数，又一次启动MySQL服务后就还原了。
解决这个问题：
要彻底解决这个问题还是要改动my.cnf配置文件，这里使用VI来改动，输入命令：vi /usr/my.cnf 回车；打开文件后按“i”键进入编辑状态；
在“[mysqld]”以下加入“max_connections=3600”。按Esc键进入命令模式。输入“:wq”回车（保存并退出）。
运行：service mysql restart 又一次启动MySQL服务；启动服务的时间可能有点长。耐心等待……
注意：非常多文章中提到在“[mysqld]”以下加入“set-variable=max_connections=1000”，根本不行，加了之后服务就启动不了了。
我这的环境是：CentOS 6.5 MySQL 5.6