架构不会被丢弃在hbmddl.auto = create.drop

Question

我使用hbmddl.auto集合在hibernate配置文件中创建并使用它在网络模式下连接到derby数据库（不嵌入，不知道这是否是相关）。

这里是我的hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC 
     "-//Hibernate/Hibernate Configuration DTD 3.0//EN" 
     "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> 
<hibernate-configuration> 

    <session-factory> 

     <!-- Database connection settings --> 
     <property name="connection.driver_class">org.apache.derby.jdbc.ClientDriver</property> 
     <property name="connection.url">jdbc:derby://localhost:1527/HibernateDb;create=true</property> 
     <property name="connection.username">admin</property> 
     <property name="connection.password">admin</property> 

     <!-- JDBC connection pool (use the built-in) --> 
     <property name="connection.pool_size">1</property> 

     <!-- SQL dialect --> 
     <property name="dialect">org.hibernate.dialect.DerbyDialect</property> 

     <!-- Disable the second-level cache --> 
     <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property> 

     <!-- Echo all executed SQL to stdout --> 
     <property name="show_sql">true</property> 

     <!-- Drop and re-create the database schema on startup --> 
     <property name="hbm2ddl.auto">create-drop</property> 

     <!-- Names the annotated entity class --> 
     <mapping class="org.asif.javabrains.dto.UserDetails"/> 

    </session-factory> 

</hibernate-configuration> 

但是当我运行正在使用此又名服务类的Java程序中，我似乎并没有删除数据库并重新创建它。正如评论所说（我从hibernate示例中获取配置文件）。

~~~~ UPDATE ~~~~

我得出结论，就是hbm2ddl是不会放弃基于以下行为

我有2类，像下面

@Entity 
public class UserDetails { 

    @Id @GeneratedValue(strategy=GenerationType.AUTO) 
    private int userId; 
    private String userName; 

    @OneToMany 
    @JoinTable(name="USER_VEHICLE", 
       joinColumns=@JoinColumn(name="USER_ID"), 
       inverseJoinColumns = @JoinColumn(name="VEHICLE_ID") 
    )  
    private Collection<Vehicle> vehicles = new ArrayList<Vehicle>() ; 

     /* getters and setters */ 
} 

架构

和

@Entity 
public class Vehicle { 
    @Id @GeneratedValue 
    private int vehicleId; 
    private String vehicleName; 
    @ManyToOne 
    @JoinColumn(name="USER_ID") 
    private UserDetails user; 

     /* getters and setters */ 
} 

和相应的休眠配置是

<!--boiler plate--> 

    <!-- Drop and re-create the database schema on startup --> 
    <property name="hbm2ddl.auto">create</property> 

    <!-- Names the annotated entity class --> 
    <mapping class="org.asif.javabrains.dto.UserDetails"/> 
    <mapping class="org.asif.javabrains.dto.Vehicle"/> 

    <!--boiler plate--> 

现在，当我改变上面的类

@Entity 
    public class UserDetails { 

     @Id @GeneratedValue(strategy=GenerationType.AUTO) 
     private int userId; 
     private String userName; 

     @OneToMany(mappedBy="user") 
     private Collection<Vehicle> vehicles = new ArrayList<Vehicle>() ; 
    //rest is same 

和

@Entity 
public class Vehicle { 
    @Id @GeneratedValue 
    private int vehicleId; 
    private String vehicleName; 
    @ManyToOne 
    @JoinColumn(name="USER_ID") 
    private UserDetails user; 
     //rest is same 

以下是打印到控制台

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". 
SLF4J: Defaulting to no-operation (NOP) logger implementation 
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details. 
Hibernate: insert into UserDetails (userId, userName) values (default, ?) 
Hibernate: values identity_val_local() 
Hibernate: insert into Vehicle (vehicleId, USER_ID, vehicleName) values (default, ?, ?) 
Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not insert: [org.asif.javabrains.dto.Vehicle] 
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:92) 
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) 
    at org.hibernate.id.insert.AbstractSelectingDelegate.performInsert(AbstractSelectingDelegate.java:64) 
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2345) 
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2852) 
    at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71) 
    at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273) 
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:320) 
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203) 
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:129) 
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210) 
    at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56) 
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195) 
    at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50) 
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93) 
    at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:713) 
    at org.hibernate.impl.SessionImpl.save(SessionImpl.java:701) 
    at org.hibernate.impl.SessionImpl.save(SessionImpl.java:697) 
    at org.asif.javabrains.hibernate.HibernateTest.main(HibernateTest.java:33) 
Caused by: java.sql.SQLSyntaxErrorException: 'USER_ID' is not a column in table or VTI 'ADMIN.VEHICLE'. 
    at org.apache.derby.client.am.SQLExceptionFactory40.getSQLException(Unknown Source) 
    at org.apache.derby.client.am.SqlException.getSQLException(Unknown Source) 
    at org.apache.derby.client.am.Connection.prepareStatement(Unknown Source) 
    at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:534) 
    at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:116) 
    at org.hibernate.id.insert.AbstractSelectingDelegate.performInsert(AbstractSelectingDelegate.java:54) 
    ... 16 more 
Caused by: org.apache.derby.client.am.SqlException: 'USER_ID' is not a column in table or VTI 'ADMIN.VEHICLE'. 
    at org.apache.derby.client.am.Statement.completeSqlca(Unknown Source) 
    at org.apache.derby.client.net.NetStatementReply.parsePrepareError(Unknown Source) 
    at org.apache.derby.client.net.NetStatementReply.parsePRPSQLSTTreply(Unknown Source) 
    at org.apache.derby.client.net.NetStatementReply.readPrepareDescribeOutput(Unknown Source) 
    at org.apache.derby.client.net.StatementReply.readPrepareDescribeOutput(Unknown Source) 
    at org.apache.derby.client.net.NetStatement.readPrepareDescribeOutput_(Unknown Source) 
    at org.apache.derby.client.am.Statement.readPrepareDescribeOutput(Unknown Source) 
    at org.apache.derby.client.am.PreparedStatement.readPrepareDescribeInputOutput(Unknown Source) 
    at org.apache.derby.client.am.PreparedStatement.flowPrepareDescribeInputOutput(Unknown Source) 
    at org.apache.derby.client.am.PreparedStatement.prepare(Unknown Source) 
    at org.apache.derby.client.am.Connection.prepareStatementX(Unknown Source) 
    ... 20 more 

这似乎消失时我手动删除表并执行ag艾因。什么可能导致这种行为。

Answer 1

该评论实际上是不正确的。由于quite a long time ago，与“创建”相比，“创建 - 删除”的真实行为是前者在关闭SessionFactory时删除模式。 “创建”本身会执行评论所说的内容，即放弃架构并在启动时重新创建它。为了验证，设置“org.hibernate作为”日志来跟踪将表明，无论是“创造”或“创造降”，该模式在启动时降低，然后创建：

INFO - Running hbm2ddl schema export 
DEBUG - import file not found: /import.sql 
INFO - exporting generated schema to database 
TRACE - total checked-out connections: 0 
TRACE - using pooled JDBC connection, pool size: 0 
DEBUG - alter table Bar drop constraint FK103F39E150191 
DEBUG - Unsuccessful: alter table Bar drop constraint FK103F39E150191 
DEBUG - Table "BAR" not found; SQL statement: 
alter table Bar drop constraint FK103F39E150191 [42102-149] 
DEBUG - drop table Bar if exists 
DEBUG - drop table Foo if exists 
DEBUG - create table Bar (id integer generated by default as identity, foo_id integer, primary key (id)) 
DEBUG - create table Foo (id integer generated by default as identity, primary key (id)) 
DEBUG - alter table Bar add constraint FK103F39E150191 foreign key (foo_id) references Foo 
INFO - schema export complete 

然而，在关机（SessionFactory的.close（））， “创造” 给出

INFO - closing 
INFO - cleaning up connection pool: jdbc:h2:file:D:/dev/projects/testbed/test-db-for-hibernate-create-drop 

，而以 “创造降”，你会看到

INFO - closing 
INFO - Running hbm2ddl schema export 
DEBUG - import file not found: /import.sql 
INFO - exporting generated schema to database 
TRACE - total checked-out connections: 0 
TRACE - using pooled JDBC connection, pool size: 0 
DEBUG - alter table Bar drop constraint FK103F39E150191 
DEBUG - drop table Bar if exists 
DEBUG - drop table Foo if exists 
INFO - schema export complete 
TRACE - returning connection to pool, pool size: 1 
INFO - cleaning up connection pool: jdbc:h2:file:D:/dev/projects/testbed/test-db-for-hibernate-create-drop 

你可以自己尝试一下：

git clone git@github.com:zzantozz/testbed tmp 
cd tmp 
mvn compile exec:java -Dexec.mainClass=rds.hibernate.Main -pl hibernate-create-drop 

Answer 2

您可能忘了拨打sessionFactory.close()，就像我犯的错误一样。突然退出不会干净优雅。

使用create-drop，当明确关闭SessionFactory时，数据库模式将被丢弃。

- Hibernate Community Documentation, Chapter 3. Configuration。