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

Posted 2021-03-12 King-D

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

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:827)
    at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:447)
    at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:237)
    at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199)
    at java.sql.DriverManager.getConnection(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:247)
    at com.baomidou.mybatisplus.generator.config.DataSourceConfig.getConn(DataSourceConfig.java:183)
    at com.baomidou.mybatisplus.generator.config.builder.ConfigBuilder.handlerDataSource(ConfigBuilder.java:270)
    at com.baomidou.mybatisplus.generator.config.builder.ConfigBuilder.<init>(ConfigBuilder.java:136)
    at com.baomidou.mybatisplus.generator.AutoGenerator.execute(AutoGenerator.java:92)
    at com.chinanums.order.admin.code.CodeGenerator.main(CodeGenerator.java:104)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    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:105)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
    at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)
    at com.mysql.cj.NativeSession.connect(NativeSession.java:150)
    at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:947)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:817)
    ... 10 more
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)
    ... 13 more
Exception in thread "main" java.lang.NullPointerException
    at com.baomidou.mybatisplus.generator.config.builder.ConfigBuilder.getTablesInfo(ConfigBuilder.java:442)
    at com.baomidou.mybatisplus.generator.config.builder.ConfigBuilder.handlerStrategy(ConfigBuilder.java:282)
    at com.baomidou.mybatisplus.generator.config.builder.ConfigBuilder.<init>(ConfigBuilder.java:143)
    at com.baomidou.mybatisplus.generator.AutoGenerator.execute(AutoGenerator.java:92)
    at com.chinanums.order.admin.code.CodeGenerator.main(CodeGenerator.java:104)

因为是使用的公司内的数据库，没有连接到数据库，所以才报这样的异常。

能够连接上公司内的数据库，就不会出现这样的异常情况了’