高分请帮忙解决hibernate入门例子

Question

C:\workspace\HibernateTest>ant run
Buildfile: build.xmlinit:build:run:
     [java] log4j:WARN No appenders could be found for logger (net.sf.hibernate.
cfg.Environment).
     [java] log4j:WARN Please initialize the log4j system properly.
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java] Init sessionFactory failed!net.sf.hibernate.MappingException: could
not instantiate id generator
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.InsertRecord(Unknown Source)
     [java]     at Test.main(Unknown Source)
     [java] java.lang.NullPointerException
     [java]     at HibernateUtil.CurrentSession(Unknown Source)
     [java]     at Test.QueryAll(Unknown Source)
     [java]     at Test.main(Unknown Source)BUILD SUCCESSFUL
Total time: 4 seconds

Answer 1

主要的错误是：
     [java] Init sessionFactory failed!net.sf.hibernate.MappingException: could
not instantiate id generator是用这个sql语句建立的表格：
CREATE TABLE cat
(
    CatID INTEGER NOT NULL PRIMARY KEY, 
    name VARCHAR(12) NOT NULL
);或者映射文件Cat.hbm.xml有问题？
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
    
<hibernate-mapping>
<class name="Cats" table="cat">
    <id
        name="catId"
        type="java.lang.String"
        column="CatID"
    >
        <generator class="unsigned" />
    </id>    <property
        name="name"
        type="java.lang.String"
        column="name"
        length="32"
    />
</class>
</hibernate-mapping>

Answer 2

你的Generator Class写得不对，
你没有指定正确的Id生成方法。
你可以试一下
<generator class="native" />
或者increment

Answer 3

呵呵，搞掂了，是自己的问题，Cats类的ID设成String了，结贴！