报错：org.hibernate.AssertionFailure: null id in com.tt.hibernate.entities.News entry (don't flush the Session after an exception occurs)

在使用hibernate创建数据库的表格时，出现了如下报错：

十二月 28, 2016 10:17:02 上午 org.hibernate.tool.hbm2ddl.SchemaExport perform
ERROR: HHH000389: Unsuccessful: create table NEWS (ID integer not null auto_increment, TITLE varchar(255), AUTHOR varchar(255), DATE datetime, DESC varchar(255), CONTENT varchar(255), IMAGE longblob, primary key (ID)) ENGINE=InnoDB
十二月 28, 2016 10:17:02 上午 org.hibernate.tool.hbm2ddl.SchemaExport perform
ERROR: 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 'DESC varchar(255),
CONTENT varchar(255),
IMAGE longblob,
' at line 6
十二月 28, 2016 10:17:02 上午 org.hibernate.tool.hbm2ddl.SchemaExport execute
INFO: HHH000230: Schema export complete
Hibernate:
create table NEWS (
ID integer not null auto_increment,
TITLE varchar(255),
AUTHOR varchar(255),
DATE datetime,
DESC varchar(255),
CONTENT varchar(255),
IMAGE longblob,
primary key (ID)
) ENGINE=InnoDB
Hibernate:
insert
into
NEWS
(TITLE, AUTHOR, DATE, DESC, CONTENT, IMAGE)
values
(?, ?, ?, ?, ?, ?)
十二月 28, 2016 10:17:03 上午 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
WARN: SQL Error: 1064, SQLState: 42000
十二月 28, 2016 10:17:03 上午 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: 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 'DESC, CONTENT, IMAGE) values ('CC', 'cc', '2016-12-28 10:17:02.785', 'DESC', 'CO' at line 1
destroy...
十二月 28, 2016 10:17:03 上午 org.hibernate.AssertionFailure <init>
ERROR: HHH000099: an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session): org.hibernate.AssertionFailure: null id in com.tt.hibernate.entities.News entry (don't flush the Session after an exception occurs)

各部分代码如下：

HibernateTest.java：

 1 package com.tt.hibernate.entities;
 2 
 3 import java.io.FileInputStream;
 4 import java.io.IOException;
 5 import java.io.InputStream;
 6 import java.sql.Blob;
 7 import java.sql.Connection;
 8 import java.sql.SQLException;
 9 import java.util.Date;
10 
11 import org.hibernate.Hibernate;
12 import org.hibernate.Session;
13 import org.hibernate.SessionFactory;
14 import org.hibernate.Transaction;
15 import org.hibernate.cfg.Configuration;
16 import org.hibernate.jdbc.Work;
17 import org.hibernate.service.ServiceRegistry;
18 import org.hibernate.service.ServiceRegistryBuilder;
19 import org.junit.After;
20 import org.junit.Before;
21 import org.junit.Test;
22 
23 public class HibernateTest {
24 
25     private SessionFactory sessionFactory;
26     private Session session;
27     private Transaction transaction;
28     
29     @Before
30     public void init(){
31         System.out.println("init...");
32         
33         Configuration configuration = new Configuration().configure();
34         ServiceRegistry serviceRegistry = 
35                 new ServiceRegistryBuilder().applySettings(configuration.getProperties())
36                                             .buildServiceRegistry();
37         sessionFactory = configuration.buildSessionFactory(serviceRegistry);
38         
39         session = sessionFactory.openSession();
40         
41         transaction = session.beginTransaction();
42     }
43     
44     @After
45     public void destroy() {
46         System.out.println("destroy...");
47         
48         transaction.commit();
49         session.close();
50         sessionFactory.close();
51     }
68     
69     @Test
70     public void testBlob() throws IOException, SQLException{
71         News news = new News();
72         
73         news.setAuthor("cc");
74         news.setTitle("CC");
75         news.setDesc("DESC");
76         news.setContent("CONTENT");
77         news.setDate(new Date());
78         
79         InputStream stream = new FileInputStream("SHQ.jpg");
80         Blob image = Hibernate.getLobCreator(session)
81                               .createBlob(stream, stream.available());
82         
83         news.setImage(image);
84         
85         session.save(news);
92     }

Hibernate.cfg.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE hibernate-configuration PUBLIC
 3         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
 5 <hibernate-configuration>
 6     <session-factory>
 7     
 8         <!-- Hibernate连接数据库的基本信息 -->
 9         <property name="conncection.username">root</property>
10         <property name="connection.password">1234</property>
11         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
12         <property name="connection.url">jdbc:mysql://localhost:3306/Hibernate</property>
13         
14         <!-- Hibernate的基本配置 -->
15         
16         <!-- Hibernate使用的数据库方言 -->
17         <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
18         
19         <!-- 运行时是否打印SQL -->
20         <property name="show_sql">true</property>
21         
22         <!-- 运行时是否格式化SQL -->
23         <property name="format_sql">true</property>
24         
25         <!-- 生成数据表的策略 -->
26         <property name="hbm2ddl.auto">create</property>
27         
28         <!-- 设置Hibernate的事务隔离级别 ：2代表读已提交-->
29         <property name="connection.isolation">2</property>
30         
31         <!-- 删除对象后，使其OID设置为null -->
32         <property name="use_identifier_rollback">true</property>      
33         
34         <!-- 配置C3P0数据源 -->
35         <property name="hibernate.c3p0.max_size">10</property>
36         <property name="hibernate.c3p0.min_size">5</property>
37         <property name="hibernate.c3p0.acquire_increment">2</property>
38         
39         <property name="hibernate.c3p0.idle_test_period">2000</property>
40         <property name="hibernate.c3p0.timeout">2000</property>
41         
42         <property name="hibernate.c3p0.max_statements">10</property>
43         
44         <!-- 设定JDBC的statement读取数据的时候每次从数据库中取出的记录条数 -->
45         <property name="hibernate.jdbc.fetch_size">100</property>
46         
47         <!-- 设定对数据库进行批量删除，批量更新和批量插入的时候的批次大小 -->
48         <property name="jdbc.batch_size">30</property>
49          
50         <!-- 需要关联的hibernate映射文件 .jbm.xml -->
51         <mapping resource="com/tt/hibernate/entities/News.hbm.xml"/>
52         <!--  <mapping resource="com/tt/hibernate/entities/Worker.hbm.xml"/>-->
53         
54     </session-factory>
55 </hibernate-configuration>

News.hbm.xml

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 4 <!-- Generated 2016-12-25 12:12:49 by Hibernate Tools 3.5.0.Final -->
 5 <hibernate-mapping package="com.tt.hibernate.entities">
 6     <class name="News" table="NEWS">
 7         <id name="id" type="java.lang.Integer">
 8             <column name="ID" />
 9             <generator class="native" />
10         </id>
11         <property name="title" type="java.lang.String">
12             <column name="TITLE" />
13         </property>
14         <property name="author" type="java.lang.String">
15             <column name="AUTHOR" />
16         </property>
17         <property name="date" type="java.util.Date">
18             <column name="DATE" />
19         </property>
20         <property name="desc" type="java.lang.String">
21             <column name="DESC" />
22         </property>
23         <property name="content" type="java.lang.String">
24             <column name="CONTENT" />
25         </property>
26         <property name="image" type="java.sql.Blob">
27             <column name="IMAGE" />
28         </property>
29     </class>
30 </hibernate-mapping>

根据报错信息，定位到SQL语句的第6行：Content varchar(255)

症状分析：

如果将News.hbm.xml文件里的desc属性设置改为下面的映射派生属性，运行正常而且可以看到news表格里是没有DESC这一列。

那么为什么会出现这样的现象？为什么desc只能作为派生属性存在呢？它和title、author和date存在什么区别？唯一的区别后三者作为参数参与了new News对象的创建。具体原因还需要深究。

posted on 2016-12-28 12:01 阳台煮酒阅读(3802) 评论(0) 编辑收藏举报

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