第三次 orm自动建表及遇到的问题

2022-09-06 11:29:25

Hibernate支持自动建表，在开发阶段很方便，可以保证hbm与数据库表结构的自动同步。

方法很简单，在hibernate.cfg.xml内加入

<property name="hibernate.hbm2ddl.auto">update</property>

update：(推荐使用) 自动生成表.如果已经存在不会再生成.如果表有变动.自动更新表(不会删除任何数据).

在这里还有其他几个参数：

create：自动建表.每次框架运行都会创建新的表.以前表将会被覆盖,表数据会丢失.(开发环境中测试使用)

create-drop：自动建表.每次框架运行结束都会将所有表删除.(开发环境中测试使用)

validate：校验.不自动生成表.每次启动会校验数据库中表是否正确.校验失败.

测试用例：

实体类User

package com.domain;

public class User {
    private Integer id;
    private String username;
    private String password;
    private Integer age;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", password=" + password + ", age=" + age + "]";
    }

}

User.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <!-- name: 完整类名    table:数据库表名 -->
    <class name="com.domain.User" table="user">
        <!-- id配置表的主键  name代表表中属性 -->
        <id name="id" column="id">
            <!-- 主键生成策略 -->
            <generator class="native"></generator>
        </id>
        <property name="username" column="username" type="string"></property>
        <property name="password" column="password" type="string"></property>
        <property name="age" column="age" type="integer"></property>
    </class>
</hibernate-mapping>

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!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>
            <!-- 指定方言 -->
            <property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
             <!-- 数据库驱动 -->
            <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
             <!-- 数据库url -->
            <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate02_1514010311</property>
             <!-- 数据库连接用户名 -->
            <property name="hibernate.connection.username">root</property>
             <!-- 数据库连接密码 -->
            <property name="hibernate.connection.password">0x3137</property>
            <!-- 将hibernate生成的sql语句打印到控制台 -->
            <property name="hibernate.show_sql">true</property>
            <!-- 将hibernate生成的sql语句格式化(语法缩进) -->
            <property name="hibernate.format_sql">true</property>
            <!-- 配置getCurrentSession -->
            <property name="hibernate.current_session_context_class">thread</property>

            <!-- 配置sql语句生成方式 -->
            <property name="hibernate.hbm2ddl.auto">update</property>

            <mapping resource="com/domain/User.hbm.xml" />
        </session-factory>

    </hibernate-configuration>

HibernateUtil.java

package com.util;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
    private static Configuration cfg;
    private static SessionFactory sessionFactory;
    static {
        try {
            cfg = new Configuration().configure();
            sessionFactory = cfg.buildSessionFactory();
        }catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

TestUser.java

package com.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.junit.Test;

import com.domain.User;
import com.util.HibernateUtil;

public class TestUser {
    @Test
    public void saveUser() {
        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction transaction = null;
        User user = new User();
        user.setUsername("三哥无邪");
        user.setPassword("1514010311");
        user.setAge(21);
        try {
            sessionFactory = HibernateUtil.getSessionFactory();
            session = sessionFactory.getCurrentSession();
            transaction = session.beginTransaction();
            session.save(user);
            transaction.commit();
        } catch (Exception e) {
            if (transaction!=null) {
                transaction.rollback();
            }
            e.printStackTrace();
        }
    }

    @Test
    public void updateUser() {

        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction transaction = null;
        try {
            sessionFactory = HibernateUtil.getSessionFactory();
            session = sessionFactory.getCurrentSession();
            transaction = session.beginTransaction();
            User user = session.get(User.class, 1);
            user.setUsername("三哥无邪啊");
            user.setPassword("1514010311");
            user.setAge(21);
            session.update(user);
            transaction.commit();
        } catch (Exception e) {
            if (transaction!=null) {
                transaction.rollback();
            }
            e.printStackTrace();
        }
    }

    @Test
    public void queryUser() {

        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction transaction = null;
        try {
            sessionFactory = HibernateUtil.getSessionFactory();
            session = sessionFactory.getCurrentSession();
            transaction = session.beginTransaction();
            User user = session.get(User.class, 2);
            System.out.println("ID:"+user.getId()+" 用户名："+user.getUsername()+" 密码："+user.getPassword());
            transaction.commit();
        } catch (Exception e) {
            if (transaction!=null) {
                transaction.rollback();
            }
            e.printStackTrace();
        }
    }
    @Test
    public void deleteUser() {

        SessionFactory sessionFactory = null;
        Session session = null;
        Transaction transaction = null;
        try {
            sessionFactory = HibernateUtil.getSessionFactory();
            session = sessionFactory.getCurrentSession();
            transaction = session.beginTransaction();
            User user = session.get(User.class, 1);
            session.delete(user);
            transaction.commit();
        } catch (Exception e) {
            if (transaction!=null) {
                transaction.rollback();
            }
            e.printStackTrace();
        }
    }
}

测试saveUser方法，测试结果如图

自动创建了user表，然后向表内插入数据

遇到的问题

运行时出现以下错误

23:37:12,245  WARN pooling:70 - HHH10001002: Using Hibernate built-in connection pool (not for production use!)
Hibernate: 

    drop table if exists user
Hibernate: 

    create table user (
       id integer not null auto_increment,
        username varchar(255),
        password varchar(255),
        age integer,
        primary key (id)
    ) type=MyISAM
23:37:13,303  WARN ExceptionHandlerLoggedImpl:27 - GenerationTarget encountered exception accepting command : Error executing DDL via JDBC Statement
org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:67)
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.applySqlString(SchemaCreatorImpl.java:440)
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.applySqlStrings(SchemaCreatorImpl.java:424)
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.createFromMetadata(SchemaCreatorImpl.java:315)
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.performCreation(SchemaCreatorImpl.java:166)
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.doCreation(SchemaCreatorImpl.java:135)
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.doCreation(SchemaCreatorImpl.java:121)
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:155)
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:72)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:309)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:452)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:710)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726)
    at com.util.HibernateUtil.<clinit>(HibernateUtil.java:12)
    at com.test.TestUser.saveUser(TestUser.java:23)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'type=MyISAM' at line 7
    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:411)
    at com.mysql.jdbc.Util.getInstance(Util.java:386)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1054)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4237)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4169)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2617)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2778)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2819)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2768)
    at com.mysql.jdbc.StatementImpl.execute(StatementImpl.java:894)
    at com.mysql.jdbc.StatementImpl.execute(StatementImpl.java:732)
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:54)
    ... 37 more
Hibernate:
    insert
    into
        user
        (username, password, age)
    values
        (?, ?, ?)
23:37:13,441  WARN SqlExceptionHelper:129 - SQL Error: 1146, SQLState: 42S02
23:37:13,441 ERROR SqlExceptionHelper:131 - Table 'hibernate02_1514010311.user' doesn't exist
org.hibernate.exception.SQLGrammarException: could not execute statement
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:63)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208)
    at org.hibernate.dialect.identity.GetGeneratedKeysDelegate.executeAndExtract(GetGeneratedKeysDelegate.java:57)
    at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:42)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2909)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3480)
    at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:81)
    at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:626)
    at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:280)
    at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:261)
    at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:306)
    at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:318)
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:275)
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:113)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:689)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:681)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:676)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:355)
    at com.sun.proxy.$Proxy26.save(Unknown Source)
    at com.test.TestUser.saveUser(TestUser.java:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'hibernate02_1514010311.user' doesn't exist
    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:411)
    at com.mysql.jdbc.Util.getInstance(Util.java:386)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1054)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4237)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4169)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2617)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2778)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2825)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2156)
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2459)
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2376)
    at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2360)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:205)
    ... 51 more

在网络上查询得到结果

目前配置的mysql方言

<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

根据错误内容提示很显然得知：这是MySQL的版本问题导致的问题。

实际上，在MySQL5.0以前，type=InnoDB是有效的SQL语句，但是自己用的是MySQL5.7版本，type=InnoDB不再有效了。

对于出现的错误，解决方法就是将mysql的方言改为如下

<property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>

就此再次运行就可以自动建表了。

码农公寓

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