jdbc链接Sql Server数据库时报错，以前没用过Sql Server数据库连接，不知道是什么原因，请高手指点。

jdbc链接Sql Server数据库时报错，以前没用过Sql Server数据库连接，不知道是什么原因，请高手指点。

2011-6-8 17:31:10 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet CheckLoginServlet threw exception
java.lang.RuntimeException: 取得数据库连接失败
at com.wanczy.dbutil.ConnectionManager.getConnection(ConnectionManager.java:59)
at com.wanczy.dbutil.DBAccess.executeQuery(DBAccess.java:182)
at cn.jx.ecjtu.oa.ps.dao.impl.LoginUserDaoImpl.findByLoginName(LoginUserDaoImpl.java:69)
at cn.jx.ecjtu.oa.services.impl.SysUserServiceImpl.checkUser(SysUserServiceImpl.java:102)
at cn.jx.ecjtu.oa.servlets.users.CheckLoginServlet.doPost(CheckLoginServlet.java:68)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.jx.ecjtu.oa.common.filter.CacheControlFilter.doFilter(CacheControlFilter.java:47)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.jx.ecjtu.oa.common.filter.CharsetFilter.doFilter(CharsetFilter.java:42)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.jx.ecjtu.oa.common.filter.PermissionFilter.doFilter(PermissionFilter.java:56)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!
[Cause: 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)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at com.wanczy.dbutil.ConnectionManager.getConnection(ConnectionManager.java:57)
at com.wanczy.dbutil.DBAccess.executeQuery(DBAccess.java:182)
at cn.jx.ecjtu.oa.ps.dao.impl.LoginUserDaoImpl.findByLoginName(LoginUserDaoImpl.java:69)
at cn.jx.ecjtu.oa.services.impl.SysUserServiceImpl.checkUser(SysUserServiceImpl.java:102)
at cn.jx.ecjtu.oa.servlets.users.CheckLoginServlet.doPost(CheckLoginServlet.java:68)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.jx.ecjtu.oa.common.filter.CacheControlFilter.doFilter(CacheControlFilter.java:47)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.jx.ecjtu.oa.common.filter.CharsetFilter.doFilter(CharsetFilter.java:42)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.jx.ecjtu.oa.common.filter.PermissionFilter.doFilter(PermissionFilter.java:56)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
]
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:111)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at com.wanczy.dbutil.ConnectionManager.getConnection(ConnectionManager.java:57)
... 27 more