我刚刚创建了一个新的虚拟机，它最初是完全干净的 -
我已经安装了 MySQL，设置了密码，现在我可以通过 PHPMyAdmin 访问它。
我复制了我的 java 应用程序，其配置与我的其他服务器上运行的相同。但它似乎很难连接到 MySQL 服务器。
你可以看到 MySQL 正在监听：
# netstat -tap
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 localhost:mysql *:* LISTEN 5307/mysqld
在 TOP 中，我可以看到这两个过程：
5196 root 20 0 3956 632 508 S 0 0.0 0:00.00 mysqld_safe
5307 mysql 20 0 167m 33m 6780 S 0 0.8 0:00.47 mysqld
但是一旦我尝试运行应用程序，我最终会在 Hibernate 尝试连接时结束：
23:46:10,192 INFO org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl:127 - HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://localhost/goout2?autoReconnect=true]
23:46:10,192 INFO org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl:132 - HHH000046: Connection properties: {user=goout2, writedelay=0, password=****, autocommit=true, shutdown=true, characterEncoding=UTF-8, charSet=UTF-8, release_mode=auto}
23:46:14,331 WARN org.hibernate.engine.jdbc.internal.JdbcServicesImpl:169 - HHH000342: Could not obtain connection to query metadata : Could not create connection to database server. Attempted reconnect 3 times. Giving up.
23:46:14,340 INFO org.hibernate.dialect.Dialect:122 - HHH000400: Using dialect: org.hibernate.dialect.MySQL5InnoDBDialect
23:46:14,350 INFO org.hibernate.engine.jdbc.internal.LobCreatorBuilder:85 - HHH000422: Disabling contextual LOB creation as connection was null
23:46:14,362 INFO org.hibernate.engine.transaction.internal.TransactionFactoryInitiator:73 - HHH000268: Transaction strategy: org.hibernate.engine.transaction.internal.jdbc.JdbcTransactionFactory
23:46:14,367 INFO org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory:48 - HHH000397: Using ASTQueryTranslatorFactory
23:46:14,944 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:182 - HHH000228: Running hbm2ddl schema update
23:46:14,944 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:193 - HHH000102: Fetching database metadata
23:46:18,949 ERROR org.hibernate.tool.hbm2ddl.SchemaUpdate:201 - HHH000319: Could not get database metadata
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
使用 C3P0，它会像这样死去：
23:58:08,696 INFO com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource:462 - Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@2e902532 [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@43a8e988 [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> false, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> ahkzhz8n1trd1gkc8ious|37e8cf51, idleConnectionTestPeriod -> 600, initialPoolSize -> 3, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 300, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 20, maxStatements -> 50, maxStatementsPerConnection -> 0, minPoolSize -> 5, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@78875ab8 [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> ahkzhz8n1trd1gkc8ious|20053644, jdbcUrl -> jdbc:mysql://localhost:5307/goout2?autoReconnect=true, properties -> {user=******, writedelay=0, password=******, autocommit=true, shutdown=true, characterEncoding=UTF-8, charSet=UTF-8, release_mode=auto} ], preferredTestQuery -> null, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> ahkzhz8n1trd1gkc8ious|347c8e1c, numHelperThreads -> 3 ]
23:58:28,694 WARN com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector:608 - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@457e133d -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
23:58:28,697 WARN com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector:624 - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@457e133d -- APPARENT DEADLOCK!!! Complete Status:
显然 MySQL 不想接受来自我的 Java 应用程序的连接，并且 MySQL 日志不显示任何内容。我想，有一些我不知道的配置选项。
谢谢。