问题

帆软报表在新增MySQL的数据连接时，报错：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 32 milliseconds ago.  The last packet sent successfully to the server was 32 milliseconds ago.
	at sun.reflect.GeneratedConstructorAccessor319.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:989)
	at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:203)
	at com.mysql.jdbc.MysqlIO.negotiateSSLConnection(MysqlIO.java:4901)
	at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1659)
	at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2191)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2222)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2017)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:779)
	at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
	at sun.reflect.GeneratedConstructorAccessor314.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
	at com.fr.third.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1461)
	at com.fr.third.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1525)
	at com.fr.third.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2165)
Caused by: javax.net.ssl.SSLException: Received fatal alert: protocol_version
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:154)
	at sun.security.ssl.SSLSocketImpl.recvAlert(SSLSocketImpl.java:2020)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1127)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1367)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1395)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1379)
	at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:188)
	... 17 more

解决

思路：从报错信息来看是Java报错，因此想到了Java中jdbc连接MySQL的配置。然后又从报错信息中获取到关键信息Caused by: javax.net.ssl.SSLException: Received fatal alert，jdbc在连接MySQL时通常会在URL中写入如下信息：

?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&autoReconnect=true&useSSL=false

于是乎想着试一试的心态，在URL后拼接了?useSSL=false，然后测试连接，问题解决。

注：

• 经过博主的测试，帆软平台的数据连接失败时都会报错com.mysql.jdbc.exceptions.jdbc4.CommunicationsException，意在提示用户连接出错。报错的详细信息会同时在报错窗口中输出，博主遇到的问题可通过拼接?useSSL=false来解决，但是无法解决其它原因导致的报错。这需要大家自己来分析问题。

总结

出现报错时请先尝试阅读报错信息，只有看了报错信息才能最快地定位到报错原因进行解决。