具体报错如下
com.alibaba.druid.pool.DruidDataSource : create connection error, url: jdbc:mysql://localhost:3306/yztech_extend?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&useSSL=false, errorCode 0, state 08S01com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failureThe 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) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:827) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:447) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:237) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1464) ~[druid-1.1.2.jar!/:1.1.2] at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1529) ~[druid-1.1.2.jar!/:1.1.2] at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2185) ~[druid-1.1.2.jar!/:1.1.2]Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failureThe last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. at sun.reflect.GeneratedConstructorAccessor90.newInstance(Unknown Source) ~[na:na] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_212] at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_212] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.NativeSession.connect(NativeSession.java:150) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:947) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:817) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] ... 6 common frames omittedCaused by: java.net.ConnectException: Connection refused (Connection refused) at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_212] at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_212] at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_212] at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_212] at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_212] at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_212] at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65) ~[mysql-connector-java-8.0.17.jar!/:8.0.17] ... 9 common frames omitted 网上普遍是以下两种解决方式
1.首先检测:url是否有四大天王useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&useSSL=false
2.其次检测mysql-connecter-java数据库驱动程序与数据库版本
然后我的问题是我部署在了linux服务器上但是还是使用的localhost本来以为没问题的但是实际上也会报以上的错误
网上给出的解释: 因为 linux 连接的时候不是通过 tcp 协议，而是通过 sockect 来连接。所以 写localhost 之后就会默认去找 sockect 链接(此文件在 /var/lib/mysql/mysql.sock)。所以要用 ip(127.0.0.1)来连接，强制让它走 tcp 协议。
我也没有使用127.0.0.1来验证以上观点,我只是把localhost改成了我服务器上的ip地址即可
