报错复现

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480) ~[na:na]
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:581) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.NativeProtocol.readServerCapabilities(NativeProtocol.java:536) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.NativeProtocol.beforeHandshake(NativeProtocol.java:423) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1427) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:944) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:814) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    ... 106 common frames omitted
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
    at com.mysql.cj.protocol.FullReadInputStream.readFully(FullReadInputStream.java:67) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.SimplePacketReader.readHeaderLocal(SimplePacketReader.java:81) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:63) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:45) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:575) ~[mysql-connector-j-8.0.32.jar:8.0.32]
    ... 112 common frames omitted

解决办法

出现这个原因是因为发送给服务器的请求，服务器无法正常接收。

说通俗点将，就是在配置文件中的 mysql连接地址和端口号不对。

我去检查yml配置文件的时候，因为更换了云数据库，忘记改端口号了。

将端口号修改为mysql正确端口号即可。