首先检查：catalina.[date].log
错误信息：
信息: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
四月 09, 2018 8:16:33 上午 org.apache.catalina.core.StandardContext startInternal
严重: One or more listeners failed to start. Full details will be found in the appropriate container log file
四月 09, 2018 8:16:33 上午 org.apache.catalina.core.StandardContext startInternal
严重: Context [/xxx] startup failed due to previous errors
四月 09, 2018 8:16:34 上午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesJdbc
严重: The web application [/heychain] registered the JDBC driver [com.alibaba.druid.proxy.DruidDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
四月 09, 2018 8:16:34 上午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesJdbc
到具体站点的log目录中，找到当前的log文件，发现错误信息：
2018-04-09 08:16:33,788 [localhost-startStop-1] ERROR [com.alibaba.druid.pool.DruidDataSource] - init datasource error, url: jdbc:mysql://localhost:3306/xxx?useUnicode=true&characterEncoding=utf-8&useSSL=false java.sql.SQLException: Access denied for user 'xxx'@'localhost' (using password: YES) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1084) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4232) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4164) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:926) at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1748) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1288) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2506) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2539) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2321)
很明显了：用户没有权限访问数据库
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