通过 Hibernate JPA 连接到 MySQL [重复]答案

【问题标题】：Connecting To MySQL via Hibernate JPA [duplicate]通过 Hibernate JPA 连接到 MySQL [重复]
【发布时间】：2018-10-20 22:30:55
【问题描述】：

我有一个以前从未遇到过的问题。我正在尝试使用 Hibernate 从 Java 连接到 MySQL 数据库。该代码实际上可以在我工作的计算机上和家里的另一台计算机上运行。但在我的笔记本电脑上，它没有，即使我在它们三个上使用相同的代码/软件/版本。

这是我的持久性代码：

   <?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
    version="2.0">
    <persistence-unit name="pdbv5" transaction-type="RESOURCE_LOCAL">
        <properties>
                <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/dbv5"/>
            <property name="hibernate.connection.username" value="root"/>
            <property name="hibernate.connection.password" value="root"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL57Dialect"/>
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.hbm2ddl.auto" value="update" />
        </properties>
    </persistence-unit>
</persistence>

因为我使用的是 Maven 依赖项，所以这里是我的 pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>formation</groupId>
    <artifactId>projetv5</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>Maven Quick Start Archetype</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.39</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.17.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>5.2.17.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.1-api</artifactId>
            <version>1.0.2.Final</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.3</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

这是错误日志：

Exception in thread "main" org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:271)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:233)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:242)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:861)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:888)
    at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:58)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:55)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
    at main.Test.ajout(Test.java:29)
    at main.Test.main(Test.java:18)
Caused by: org.hibernate.exception.JDBCConnectionException: Error calling Driver#connect
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:115)
    at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator$1$1.convert(BasicConnectionCreator.java:101)
    at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.convertSqlException(BasicConnectionCreator.java:123)
    at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:41)
    at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.createConnection(BasicConnectionCreator.java:58)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.addConnections(DriverManagerConnectionProviderImpl.java:363)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.<init>(DriverManagerConnectionProviderImpl.java:282)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.<init>(DriverManagerConnectionProviderImpl.java:260)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections$Builder.build(DriverManagerConnectionProviderImpl.java:401)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildPool(DriverManagerConnectionProviderImpl.java:112)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:75)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:242)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:145)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:259)
    ... 15 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database 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.jdbc.Util.handleNewInstance(Util.java:404)
    at com.mysql.jdbc.Util.getInstance(Util.java:387)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2330)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    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.jdbc.Util.handleNewInstance(Util.java:404)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
    at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:38)
    ... 30 more
Caused by: java.lang.NullPointerException
    at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2997)
    at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1936)
    at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1865)
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1228)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284)
    ... 41 more

如果有必要，我的测试代码：

static void ajout() {

        Eleve e = new Eleve("Spirou", 2);
        Eleve e2 = new Eleve("Fantasio", 13);
        Eleve e3 = new Eleve("Seccotine", 18);
        Professeur p = new Professeur("Champignac", 200);

        EntityManagerFactory emf = Persistence.createEntityManagerFactory("pdbv5");
        EntityManager em = emf.createEntityManager();
        EntityTransaction tx = em.getTransaction();

        tx.begin();

        em.persist(e);
        em.persist(e2);
        em.persist(e3);
        em.persist(p);

        tx.commit();

        em.close();
        emf.close();

    }

仅供参考，我使用的是 MySQL 8.0 和 Eclipse Oxygen。

【问题讨论】：

标签： java mysql hibernate jpa jdbc

【解决方案1】：

我不知道该说什么...我只是想通了（嗯，不是真的）出了什么问题。 JDBC 连接器可能没有很好地加载或什么的。我只是将 maven 依赖项更改为 5.1.46，它实际上可以正常工作。我有点无语了……

    <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.46</version>
</dependency>

【讨论】：

鉴于您使用的是 MySQL 8，您可能需要考虑升级到 MySQL Connector/J 版本 8.0.11
我实际上尝试使用 8.0.11 连接器，但收到了相同的错误消息以及关于时区问题的新消息。我试图修复它，但在寻找它几个小时后没有实现......