报错：Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: java.sec

在进行单元测试发现Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: java.sec

解决方法：

"jdbc:mysql://127.0.0.1:3306/java_16blogdemo?characterEncoding=utf-8&useSSL=true";

将上面的useSSL改为false即可 。

"C:\Program Files (x86)\Java\jdk1.8.0_73\bin\java.exe" "-javaagent:F:\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=60537:F:\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\charsets.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\deploy.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\access-bridge-32.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\cldrdata.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\dnsns.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\jaccess.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\jfxrt.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\localedata.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\nashorn.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\sunec.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\sunjce_provider.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\sunmscapi.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\sunpkcs11.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\ext\zipfs.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\javaws.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\jce.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\jfr.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\jfxswt.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\jsse.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\management-agent.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\plugin.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\resources.jar;C:\Program Files (x86)\Java\jdk1.8.0_73\jre\lib\rt.jar;G:\bishe\test_maven\target\classes;F:\apache-maven-3.6.3-bin\apache-maven-3.6.3\Repository\mysql\mysql-connector-java\5.1.47\mysql-connector-java-5.1.47.jar" model.UserDao
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 1,373 milliseconds ago.  The last packet sent successfully to the server was 1,366 milliseconds ago.
	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:422)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990)
	at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:201)
	at com.mysql.jdbc.MysqlIO.negotiateSSLConnection(MysqlIO.java:4914)
	at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1663)
	at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1224)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2199)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2230)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2025)
	at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:778)
	at com.mysql.jdbc.JDBC4Connection.(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:422)
	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.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:428)
	at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:136)
	at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:107)
	at model.DBUtil.getConnection(DBUtil.java:54)
	at model.UserDao.add(UserDao.java:20)
	at model.UserDao.main(UserDao.java:85)
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(Alerts.java:192)
	at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1509)
	at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
	at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979)
	at sun.security.ssl.Handshaker.process_record(Handshaker.java:914)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)
	at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:186)
	... 21 more
Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
	at com.mysql.jdbc.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:302)
	at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:922)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1491)
	... 29 more
Caused by: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
	at sun.security.provider.certpath.PKIXCertPathValidator.validate(PKIXCertPathValidator.java:153)
	at sun.security.provider.certpath.PKIXCertPathValidator.engineValidate(PKIXCertPathValidator.java:79)
	at java.security.cert.CertPathValidator.validate(CertPathValidator.java:292)
	at com.mysql.jdbc.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:295)
	... 31 more
Exception in thread "main" java.lang.NullPointerException
	at model.UserDao.add(UserDao.java:25)
	at model.UserDao.main(UserDao.java:85)