MySQl连接报错

useSSL

后台警告信息

Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

网上很多地方提示加上 useSSL=false 就可以了，但是如果只是加上这个的话，会报错如下：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 250 milliseconds ago.  The last packet sent successfully to the server was 242 milliseconds ago.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_101]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_101]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_101]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_101]
    xxx
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) ~[na:1.8.0_101]
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949) ~[na:1.8.0_101]
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302) ~[na:1.8.0_101]
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296) ~[na:1.8.0_101]
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1509) ~[na:1.8.0_101]
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216) ~[na:1.8.0_101]
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979) ~[na:1.8.0_101]
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:914) ~[na:1.8.0_101]
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062) ~[na:1.8.0_101]
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375) ~[na:1.8.0_101]
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403) ~[na:1.8.0_101]
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387) ~[na:1.8.0_101]
    at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:186) ~[mysql-connector-java-5.1.46.jar:5.1.46]
    ... 105 common frames omitted
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$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:302) ~[mysql-connector-java-5.1.46.jar:5.1.46]
    at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:922) ~[na:1.8.0_101]
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1491) ~[na:1.8.0_101]
    ... 113 common frames omitted
Caused by: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
    at sun.security.provider.certpath.PKIXCertPathValidator.validate(PKIXCertPathValidator.java:153) ~[na:1.8.0_101]
    at sun.security.provider.certpath.PKIXCertPathValidator.engineValidate(PKIXCertPathValidator.java:79) ~[na:1.8.0_101]
    at java.security.cert.CertPathValidator.validate(CertPathValidator.java:292) ~[na:1.8.0_101]
    at com.mysql.jdbc.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:295) ~[mysql-connector-java-5.1.46.jar:5.1.46]
    ... 115 common frames omitted

解决方法如下：

在 url 后面加上 autoReconnect=true&useSSL=false
url: jdbc:mysql://10.132.241.120:3306/vue?characterEncoding=utf8&autoReconnect=true&useSSL=false

Unknown system variable 'query_cache_size'

后台报错信息如下：

java.sql.SQLException: Unknown system variable 'query_cache_size'

这个错是数据库驱动版本和数据库不一致导致的。解决方法如下：

根据自己的数据库版本去这个地址选择合适的驱动版本
https://mvnrepository.com/artifact/mysql/mysql-connector-java

比如我的数据库版本是 8.0.11，那么对应的驱动为:
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.11</version>
</dependency>

timeZone乱码

报错信息

java.sql.SQLException: The server time zone value 'ÖÐ¹ú±ê×¼Ê±¼ä' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.

这个错是因为库的时间与系统时间不符导致的。解决方法如下：

在url 后面加上 serverTimezone=GMT
url: jdbc:mysql://localhost:3306/admin?characterEncoding=utf-8&autoReconnect=true&useSSL=false&serverTimezone=GMT

'hibernate.dialect' not set

在Spring Boot下使用JPA报错：'hibernate.dialect' not set，报错信息如下：

Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set  
        at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:104)  
        at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:71)  
        at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:205)  
        at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)  
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)  
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)  
        at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)  
        at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)  
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:850)  
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:843)  
        at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.withTccl(ClassLoaderServiceImpl.java:398)  
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:842)  
        at org.hibernate.jpa.HibernatePersistenceProvider.createContainerEntityManagerFactory(HibernatePersistenceProvider.java:152)  
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:336)  
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318)  
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1613)  
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1550)  
        ... 21 more

解决方法：

在 application.yaml 文件中添加以下内容
  jpa:
    database-platform: org.hibernate.dialect.MySQL5Dialect

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