问题：JDBC连接MySQL数据库驱动时会出现：java.sql.SQLException: The server time zone value '???ú±ê×??±??' is unrecognized...的异常，具体如下：
Exception in thread "main" java.sql.SQLException: The server time zone value '?? ?ú±ê×??±??' is unrecognized or represents more than one time zone. You must c onfigure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support. at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835) at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455) at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240) at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207) at java.sql.DriverManager.getConnection(DriverManager.java:664) at java.sql.DriverManager.getConnection(DriverManager.java:247) at ConnMySql.main(ConnMySql.java:7) Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The serv er time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverT imezone configuration property) to use a more specifc time zone value if you wan t to utilize time zone support. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:85) at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:132) at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2234) at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2258) at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1319) at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:966) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825) ... 6 more
C3P0连接MySQL数据库出现如下情况，一样的解决办法
警告: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@701c25ae -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks! 二月 29, 2020 10:12:58 下午 com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run 警告: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@701c25ae -- APPARENT DEADLOCK!!! Complete Status: Managed Threads: 3 Active Threads: 3 Active Tasks: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@3fe6cfe6 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2) com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@2ec6ace1 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0) com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@e9371c9 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1) Pending Tasks: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@56594c7b com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@5fc930a9 Pool thread stack traces: Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main] java.lang.Thread.sleep(Native Method) com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805) com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547) Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main] java.lang.Thread.sleep(Native Method) com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805) com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547) Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main] java.lang.Thread.sleep(Native Method) com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805) com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547) 二月 29, 2020 10:13:08 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run 警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@2ec6ace1 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: java.sql.SQLException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support. at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835) at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455) at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240) at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207) at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137) at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014) at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32) at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810) at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547) Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support. at sun.reflect.GeneratedConstructorAccessor10.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:85) at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:132) at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2234) at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2258) at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1319) at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:966) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825) ... 11 more 二月 29, 2020 10:13:08 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run 警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@3fe6cfe6 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: java.sql.SQLException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support. at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835) at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455) at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240) at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207) at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137) at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014) at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32) at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810) at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547) Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support. at sun.reflect.GeneratedConstructorAccessor10.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:85) at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:132) at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2234) at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2258) at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1319) at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:966) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825) ... 11 more
解决办法：在jdbc连接的url后面加上serverTimezone=GMT即可解决问题。
Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test?serverTimezone=GMT","test","test");