Hibernate 4 注释 - MySQL 配置错误：java.sql.SQLException：无法添加外键约束

Question

当我尝试使用 Hibernate 4 - MySQL 配置加载我的 Spring Boot 应用程序时，出现配置堆栈跟踪错误。我不知道是什么导致了这个外键约束问题。 非常感谢您的帮助！

**Caused by: java.sql.SQLException: Cannot add foreign key constraint
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:963)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3966)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3902)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2526)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2673)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2503)
at com.mysql.jdbc.StatementImpl.executeInternal(StatementImpl.java:839)
at com.mysql.jdbc.StatementImpl.execute(StatementImpl.java:739)
at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:49)
...**

这是我的三个数据库表：

主要实体

@Entity
public class Principal implements {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long principal_id;

@Column(name = "username", unique = true, nullable = false)
private String name;

@Column(unique = true, nullable = false)
private String email;

@Column(nullable = false)
private String password;

@Column(nullable = false)
private Boolean locked;

@ManyToMany( fetch = FetchType.EAGER)
@JoinTable(joinColumns = { @JoinColumn(name = "PRINCIPAL_ID", referencedColumnName = "PRINCIPAL_ID") }, inverseJoinColumns = { @JoinColumn(name = "ROLE_ID", referencedColumnName = "ROLE_ID") })
private Set<Role> roles;


public Principal() {
    super();

    locked = false;
}

public Principal(final String nameToSet, final String passwordToSet, final Set<Role> rolesToSet) {
    super();

    name = nameToSet;
    password = passwordToSet;
    roles = rolesToSet;
}

public Principal(final UserDto userDto) {
    super();

    name = userDto.getName();
    password = userDto.getPassword();
    roles = userDto.getRoles();
}

@Override
public Long getId() {
    return principal_id;
}

@Override
public void setId(final Long idToSet) {
    principal_id = idToSet;
}

@Override
public String getName() {
    return name;
}

public void setName(final String nameToSet) {
    name = nameToSet;
}

public String getEmail() {
    return email;
}

public void setEmail(final String emailToSet) {
    email = emailToSet;
}

public String getPassword() {
    return password;
}

public void setPassword(final String passwordToSet) {
    password = passwordToSet;
}

public Set<Role> getRoles() {
    return roles;
}

public void setRoles(final Set<Role> rolesToSet) {
    roles = rolesToSet;
}

public Boolean getLocked() {
    return locked;
}

public void setLocked(final Boolean lockedToSet) {
    locked = lockedToSet;
}

}

角色实体

@Entity
public class Role implements INameableEntity, INameableDto {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long role_id;

@Column(unique = true, nullable = false)
@Size(min = 2, max = 30)
@NotNull
private String name;

public Role() {
    super();
}

public Role(final String nameToSet) {
    super();
    name = nameToSet;
}

// API

@Override
public Long getId() {
    return role_id;
}

@Override
public void setId(final Long idToSet) {
    role_id = idToSet;
}

@Override
public String getName() {
    return name;
}

public void setName(final String nameToSet) {
    name = nameToSet;
}

persistence-mysql.properties

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/qlc?&useSSL=false
jdbc.username=root
jdbc.password=password


hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.show_sql=true
hibernate.hbm2ddl.auto=update

jpa.generateDdl=true

UmPersistenceJpaConfig.java

@Configuration
@EnableTransactionManagement
@ComponentScan({ "org.qlc.um.persistence" })
@PropertySource({ "persistence-mysql.properties" })
@EnableJpaRepositories(basePackages = "org.qlc.um.persistence.dao")
public class UmPersistenceJpaConfig {

@Autowired
private Environment env;

public UmPersistenceJpaConfig() {
    super();
}

// beans

@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
    final LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
    em.setDataSource(dataSource());
    em.setPackagesToScan(new String[] { "org.qlc.um" });
    final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
    em.setJpaVendorAdapter(vendorAdapter);
    em.setJpaProperties(additionalProperties());
    return em;
}

@Bean
public DataSource dataSource() {
    final DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
    dataSource.setUrl(env.getProperty("jdbc.url"));
    dataSource.setUsername(env.getProperty("jdbc.username"));
    dataSource.setPassword(env.getProperty("jdbc.password"));
    return dataSource;
}

@Bean
public JpaTransactionManager transactionManager() {
    final JpaTransactionManager transactionManager = new JpaTransactionManager();
    transactionManager.setEntityManagerFactory(entityManagerFactory().getObject());
    return transactionManager;
}

@Bean
public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
    return new PersistenceExceptionTranslationPostProcessor();
}

//

final Properties additionalProperties() {
    final Properties hibernateProperties = new Properties();
    hibernateProperties.setProperty("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto", "create-drop"));
    hibernateProperties.setProperty("hibernate.dialect", env.getProperty("hibernate.dialect"));

    // setProperty("hibernate.hbm2ddl.auto", hibernateHbm2ddlAuto);
    // setProperty("hibernate.ejb.naming_strategy", org.hibernate.cfg.ImprovedNamingStrategy.class.getName());
    return hibernateProperties;
}

}

Answer 1

我的猜测，因为您没有在实体的 id 中标记@column，所以它采用您的 getter 的默认属性名称，即“id”

试试， 校长

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
Column(name="principal_id")
private Long principal_id;

角色

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
Column(name="role_id")
private Long role_id;