java程序启动连接mysql时报错Exception in thread "main"

Question

问题描述：

报错如下：

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.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 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.jdbc.Util.handleNewInstance(Util.java:403)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:335)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2187)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2220)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2015)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:768)
	at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
	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.jdbc.Util.handleNewInstance(Util.java:403)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:385)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:323)
	at java.sql.DriverManager.getConnection(DriverManager.java:664)
	at java.sql.DriverManager.getConnection(DriverManager.java:247)
	at cn.yh.JdbcDemo.main(JdbcDemo.java:13)
Caused by: java.net.UnknownHostException: root
	at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
	at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:929)
	at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1324)
	at java.net.InetAddress.getAllByName0(InetAddress.java:1277)
	at java.net.InetAddress.getAllByName(InetAddress.java:1193)
	at java.net.InetAddress.getAllByName(InetAddress.java:1127)
	at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:188)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:299)
	... 15 more

Process finished with exit code 1

Answer 1

应该是mysql服务停止，打开就好，在服务中检查下服务开启情况