一、启动项目报错之数据库服务未开启（Caused by: java.net.ConnectException: Connection refused: connect）
2020-12-22 18:28:51.325 INFO 16656 [1)-192.168.0.26] com.zaxxer.hikari.HikariDataSource [110] : HikariPool-1 - Starting...
2020-12-22 18:28:51.337 INFO 16656 [2)-192.168.0.26] o.s.web.servlet.DispatcherServlet [512] : FrameworkServlet 'dispatcherServlet': initialization completed in 24 ms
2020-12-22 18:28:54.619 ERROR 16656 [1)-192.168.0.26] com.zaxxer.hikari.pool.HikariPool [567] : HikariPool-1 - Exception during pool initialization.
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:425)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:342)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2197)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2230)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2025)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:778)
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:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:117)
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:123)
at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:365)
at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:194)
at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:460)
at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:534)
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112)
at com.zaxxer.hikari.HikariDataSource$$FastClassBySpringCGLIB$$eeb1ae86.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:136)
at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:124)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
at com.zaxxer.hikari.HikariDataSource$$EnhancerBySpringCGLIB$$b97a9569.getConnection(<generated>)
at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:157)
at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:324)
at org.springframework.boot.actuate.jdbc.DataSourceHealthIndicator.getProduct(DataSourceHealthIndicator.java:122)
at org.springframework.boot.actuate.jdbc.DataSourceHealthIndicator.doDataSourceHealthCheck(DataSourceHealthIndicator.java:109)
at org.springframework.boot.actuate.jdbc.DataSourceHealthIndicator.doHealthCheck(DataSourceHealthIndicator.java:104)
at org.springframework.boot.actuate.health.AbstractHealthIndicator.health(AbstractHealthIndicator.java:84)
at org.springframework.boot.actuate.health.CompositeHealthIndicator.health(CompositeHealthIndicator.java:68)
at org.springframework.boot.actuate.health.HealthEndpoint.health(HealthEndpoint.java:47)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:246)
at org.springframework.boot.actuate.endpoint.invoke.reflect.ReflectiveOperationInvoker.invoke(ReflectiveOperationInvoker.java:76)
at org.springframework.boot.actuate.endpoint.annotation.AbstractDiscoveredOperation.invoke(AbstractDiscoveredOperation.java:61)
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBean.invoke(EndpointMBean.java:126)
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBean.invoke(EndpointMBean.java:99)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)
at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)
at sun.rmi.transport.Transport$1.run(Transport.java:200)
at sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85)
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:606)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:301)
... 72 common frames omitted
2020-12-22 18:28:54.628 WARN 16656 [1)-192.168.0.26] o.s.b.a.jdbc.DataSourceHealthIndicator [89] : DataSource health check failed
... 72 common frames omitted
二、错误原因未启动mysql服务
三、解决方法，启动mysql服务
- net start mysql （对应的服务关闭命令为 net stop mysql）
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