載自：https://blog.csdn.net/ponxbin/article/details/80608040
關於版本比較新的數據庫（Mysql8.0）連接的問題：
he 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:172)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:862)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:444)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:230)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:226)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at mysqlconnect.connect.main(connect.java:24)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: 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(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:59)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:103)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:149)
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:165)
at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:355)
at com.mysql.cj.protocol.a.NativeAuthenticationProvider.negotiateSSLConnection(NativeAuthenticationProvider.java:789)
at com.mysql.cj.protocol.a.NativeAuthenticationProvider.proceedHandshakeWithPluggableAuthentication(NativeAuthenticationProvider.java:499)
at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:217)
at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1411)
at com.mysql.cj.NativeSession.connect(NativeSession.java:165)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:982)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:852)
... 6 more
Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
at sun.security.ssl.Alerts.getSSLException(Unknown Source)
at sun.security.ssl.SSLSocketImpl.fatal(Unknown Source)
at sun.security.ssl.Handshaker.fatalSE(Unknown Source)
at sun.security.ssl.Handshaker.fatalSE(Unknown Source)
at sun.security.ssl.ClientHandshaker.serverCertificate(Unknown Source)
at sun.security.ssl.ClientHandshaker.processMessage(Unknown Source)
at sun.security.ssl.Handshaker.processLoop(Unknown Source)
at sun.security.ssl.Handshaker.process_record(Unknown Source)
at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:213)
at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:206)
at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:99)
at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:350)
... 13 more
Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
at com.mysql.cj.protocol.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:280)
at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(Unknown Source)
... 25 more
Caused by: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
at sun.security.provider.certpath.PKIXCertPathValidator.validate(Unknown Source)
at sun.security.provider.certpath.PKIXCertPathValidator.engineValidate(Unknown Source)
at java.security.cert.CertPathValidator.validate(Unknown Source)
at com.mysql.cj.protocol.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:273)
... 26 more
Exception in thread "main" java.lang.NullPointerException
at mysqlconnect.connect.main(connect.java:34)
網上說的什么修改的方法對我沒有用
諸如此類：
1·修改my.ini bind-address = 127.0.0.1 為 bind-address = 0.0.0.0 使非本地網絡可以訪問數據庫
2·檢查防火牆是否有開放3306端口
3·網上廣為流傳的86400秒超時 回收機制 並不和我遇到的問題一致，這種問題是在程序運行過程中因為我們使用的連接池不知道連接被回收了所以報出的異常，解決方案可以是修改連接池配置或修改mysql空閑超時時間配置。
以上方法均沒用，主要是mysql和驅動版本的問題
我的mysql是8.0,驅動也是8.x最新的；
Class.forName("com.mysql.cj.jdbc.Driver");
url = "jdbc:mysql://localhost:3306/jnditest?serverTimezone=GMT&useSSL=false";//數據庫的路徑
主要是紅色字體方面，serverTimezone缺失是很容易從錯誤找出來的，但是重點是useSSL=false，這個從錯誤提示是看不出來的，它有個很重要的作用是使用JDBC跟你的數據庫連接的時候，你的JDBC版本與MySQL版本不兼容，MySQL的版本更高一些，在連接語句后加上“useSSL=‘true’” ，就可以連接到數據庫了。更高版本。但如果是兼容版本的話就會出錯。
我試了改成true的確又出現了這個問題。
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原文鏈接：https://blog.csdn.net/ponxbin/article/details/80608040