解决2003-Can‘t connect to MySQL server on ‘127.0.0.1‘(10060 “Unknown error“)

启动tomcat web应用程序突然报错：

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:411)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:358)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2489)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2526)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2311)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
	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:411)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:347)
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:142)
	at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:211)
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:136)
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1271)
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1325)
	at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:1215)

检查了mysql服务是正常开启的，重启再尝试连接仍然连接不上。Navicat 连接报错：

联想到最近因为勒索病毒所以把所有防火墙都打开了，而Mysql默认不允许远程登录，可能是防火墙需要开放3306端口：
控制面板\系统和安全\Windows 防火墙

1.右键新建入站规则导向

2.点击入站规则，新建规则，选择“端口”，下一步

3.输入mysql的端口号（默认是3306）

4.允许连接

5.全勾选

6.最后输入名称，完成即可

再次连接即可。