每当连接空闲时，它就会开始发出此错误。当我们刷新页面一次或两次时，它再次开始正常工作。
我们如何解决这个问题？
DEBUG DefaultConnectionTester - Connection com.mysql.jdbc.Connection@1a087ae failed default system-table Connection test with an Exception!
java.sql.SQLException: Communication link failure: java.io.EOFException, underlying cause: null
** BEGIN NESTED EXCEPTION **
java.io.EOFException
STACKTRACE:
java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1395)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:1539)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:1930)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1168)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1279)
at com.mysql.jdbc.MysqlIO.sqlQuery(MysqlIO.java:1225)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2278)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2225)
at com.mysql.jdbc.Statement.executeQuery(Statement.java:1163)
at com.mysql.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:3372)
at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(DefaultConnectionTester.java:185)
at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:62)
at com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(AbstractConnectionTester.java:67)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.finerLoggingTestPooledConnection(C3P0PooledConnectionPool.java:318)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:308)
at com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
** END NESTED EXCEPTION **
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:1714)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:1930)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1168)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1279)
at com.mysql.jdbc.MysqlIO.sqlQuery(MysqlIO.java:1225)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2278)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2225)
at com.mysql.jdbc.Statement.executeQuery(Statement.java:1163)
at com.mysql.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:3372)
at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(DefaultConnectionTester.java:185)
at com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:62)
at com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(AbstractConnectionTester.java:67)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.finerLoggingTestPooledConnection(C3P0PooledConnectionPool.java:318)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:308)
at com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
DEBUG BasicResourcePool - trace com.mchange.v2.resourcepool.BasicResourcePool@4aa512 [managed: 5, unused: 5, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@d6dc32)
DEBUG BasicResourcePool - incremented pending_acquires: 5
DEBUG C3P0PooledConnectionPool - Testing PooledConnection [com.mchange.v2.c3p0.impl.NewPooledConnection@4e6f7c] on IDLE CHECK.
DEBUG BasicResourcePool - trace com.mchange.v2.resourcepool.BasicResourcePool@4aa512 [managed: 4, unused: 4, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@d6dc32)
DEBUG BasicResourcePool - incremented pending_acquires: 6
DEBUG C3P0PooledConnectionPool - Testing PooledConnection [com.mchange.v2.c3p0.impl.NewPooledConnection@197b44c] on IDLE CHECK.
DEBUG GooGooStatementCache - checkinAll(): com.mchange.v2.c3p0.stmt.GlobalMaxOnlyStatementCache stats -- total size: 0; checked out: 0; num connections: 0; num keys: 0
DEBUG C3P0PooledConnectionPool - Test of PooledConnection [com.mchange.v2.c3p0.impl.NewPooledConnection@5aa6b3] on IDLE CHECK has FAILED.
java.sql.SQLException: Connection is invalid
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:427)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.finerLoggingTestPooledConnection(C3P0PooledConnectionPool.java:318)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:308)
at com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
DEBUG BasicResourcePool - BasicResourcePool: An idle resource is broken and will be purged. [com.mchange.v2.c3p0.impl.NewPooledConnection@5aa6b3]
java.sql.SQLException: Connection is invalid
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.finerLoggingTestPooledConnection(C3P0PooledConnectionPool.java:324)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:308)
at com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
DEBUG DefaultConnectionTester - Connection com.mysql.jdbc.Connection@13bcbbb failed default system-table Connection test with an Exception!
java.sql.SQLException: Communication link failure: java.io.EOFException, underlying cause: null