我想做一个学生登陆和注册的界面,在MyEclipse中要用一个递增的Id标识数据库元组,数据库如下
sid int not null identity(1,1),
sno int not null,
sname char(10) not null,
password char(10) not null,
primary key (sid)
用这个能做出来,但是我现在想把那个递增的sid去掉
sno int not null,
sname char(10) not null,
password char(10) not null,
primary key (sno)
这样子注册界面的插入数据库就出错……hibernate映射:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<class name="cn.edu.hhuc.hibernate.Students" table="students" schema="dbo" catalog="DBTest">
<id name="sno" type="java.lang.Integer">
<column name="sno" />
<generator class="assigned" />
</id>
<property name="sname" type="java.lang.String">
<column name="sname" length="10" not-null="true" />
</property>
<property name="password" type="java.lang.String">
<column name="password" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>
sid int not null identity(1,1),
sno int not null,
sname char(10) not null,
password char(10) not null,
primary key (sid)
用这个能做出来,但是我现在想把那个递增的sid去掉
sno int not null,
sname char(10) not null,
password char(10) not null,
primary key (sno)
这样子注册界面的插入数据库就出错……hibernate映射:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<class name="cn.edu.hhuc.hibernate.Students" table="students" schema="dbo" catalog="DBTest">
<id name="sno" type="java.lang.Integer">
<column name="sno" />
<generator class="assigned" />
</id>
<property name="sname" type="java.lang.String">
<column name="sname" length="10" not-null="true" />
</property>
<property name="password" type="java.lang.String">
<column name="password" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>
org.hibernate.exception.DataException: could not insert: [cn.edu.hhuc.hibernate.Students]
org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:77)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2078)
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2427)
org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:51)
org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:139)
org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:297)
org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
org.hibernate.impl.SessionImpl.flush(SessionImpl.java:985)
org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:333)
org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
cn.edu.hhuc.hibernate.StudentsDAO.save(StudentsDAO.java:27)
cn.edu.hhuc.struts.action.RegAction.execute(RegAction.java:64)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
public class StudentsDAO extends BaseHibernateDAO {
private static final Log log = LogFactory.getLog(StudentsDAO.class);
// property constants
public static final String SNAME = "sname";
public static final String PASSWORD = "password"; public void save(Students transientInstance) {
log.debug("saving Students instance");
try {
getSession().save(transientInstance);
getSession().beginTransaction().commit();
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<class name="cn.edu.hhuc.hibernate.Students" table="students" schema="dbo" catalog="DBTest">
<id name="sno" type="java.lang.Integer">
<column name="sno" />
<generator class="native" />
</id>
<property name="sname" type="java.lang.String">
<column name="sname" length="10" not-null="true" />
</property>
<property name="password" type="java.lang.String">
<column name="password" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>
你把那个递增的ID如果去掉的话,你应该给那个插入值啊.
不插入值肯定会报错,或者使用Hibernate产生的主键ID.
具体实现如下:<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<class name="cn.edu.hhuc.hibernate.Students" table="students" schema="dbo" catalog="DBTest">
<id name="sno" type="java.lang.Integer">
<column name="sno" />
<generator class="uuid" />
</id>
<property name="sname" type="java.lang.String">
<column name="sname" length="10" not-null="true" />
</property>
<property name="password" type="java.lang.String">
<column name="password" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>
org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:104)
org.hibernate.tuple.AbstractEntityTuplizer.setIdentifier(AbstractEntityTuplizer.java:204)
org.hibernate.persister.entity.AbstractEntityPersister.setIdentifier(AbstractEntityPersister.java:3262)
org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:157)
org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:114)
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:530)
org.hibernate.impl.SessionImpl.save(SessionImpl.java:518)
org.hibernate.impl.SessionImpl.save(SessionImpl.java:514)
cn.edu.hhuc.hibernate.StudentsDAO.save(StudentsDAO.java:26)
cn.edu.hhuc.struts.action.RegAction.execute(RegAction.java:66)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)还有<generator class="uuid" />
这里的uuid还有native之类的是什么意思呢?
配置上它 ,然后 <generator class="native" />uuid ,native 具体什么意思, 楼主上网搜搜,很多
Assigned方式由程序生成主键值,并且要在save()之前指定否则会抛出异常
特点:主键的生成值完全由用户决定,与底层数据库无关。用户需要维护主键值,在调用session.save()之前要指定主键值。HIbernate主键详解------Hilo
Hilo使用高低位算法生成主键,高低位算法使用一个高位值和一个低位值,然后把算法得到的两个值拼接起来作为数据库中的唯一主键。Hilo方式需要额外的数据库表和字段提供高位值来源。默认请况下使用的表是
hibernate_unique_key,默认字段叫作next_hi。next_hi必须有一条记录否则会出现错误。
特点:需要额外的数据库表的支持,能保证同一个数据库中主键的唯一性,但不能保证多个数据库之间主键的唯一性。Hilo主键生成方式由Hibernate维护,所以Hilo方式与底层数据库无关,但不应该手动修改hi/lo算法使用的表的值,否则会引起主键重复的异常。HIbernate主键详解------Increment
Increment方式对主键值采取自动增长的方式生成新的主键值,但要求底层数据库的支持Sequence。如Oracle,DB2等。需要在映射文件xxx.hbm.xml中加入Increment标志符的设置。
特点:由Hibernate本身维护,适用于所有的数据库,不适合多进程并发更新数据库,适合单一进程访问数据库。不能用于群集环境。HIbernate主键详解------Identity
Identity当时根据底层数据库,来支持自动增长,不同的数据库用不同的主键增长方式。
特点:与底层数据库有关,要求数据库支持Identity,如MySQl中是auto_increment, SQL Server 中是Identity,支持的数据库有MySql、SQL Server、DB2、Sybase和HypersonicSQL。 Identity无需Hibernate和用户的干涉,使用较为方便,但不便于在不同的数据库之间移植程序。HIbernate主键详解------Sequence
Sequence需要底层数据库支持Sequence方式,例如Oracle数据库等
特点:需要底层数据库的支持序列,支持序列的数据库有DB2、PostgreSql、Qracle、SAPDb等在不同数据库之间移植程序,特别从支持序列的数据库移植到不支持序列的数据库需要修改配置文件HIbernate主键详解------Native
Native主键生成方式会根据不同的底层数据库自动选择Identity、Sequence、Hilo主键生成方式
特点:根据不同的底层数据库采用不同的主键生成方式。由于Hibernate会根据底层数据库采用不同的映射方式,因此便于程序移植,项目中如果用到多个数据库时,可以使用这种方式。HIbernate主键详解------UUID
UUID使用128位UUID算法生成主键,能够保证网络环境下的主键唯一性,也就能够保证在不同数据库及不同服务器下主键的唯一性。
特点;能够保证数据库中的主键唯一性,生成的主键占用比较多的存贮空间HIbernate主键详解------Foreign GUID
Foreign用于一对一关系中。GUID主键生成方式使用了一种特殊算法,保证生成主键的唯一性,支持SQL Server和MySQL
sno int not null,
sname char(10) not null,
password char(10) not null,
primary key (sno)
这里没有sid了,组建为sno(学号),学号不可能为连续递增的……
就这个意思
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<class name="cn.edu.hhuc.hibernate.Students" table="students" schema="dbo" catalog="DBTest">
<id name="sno" type="java.lang.Integer">
<column name="sno" />
<generator class="assigned" />
</id>
<property name="sname" type="java.lang.String">
<column name="sname" length="10" not-null="true" />
</property>
<property name="password" type="java.lang.String">
<column name="password" length="10" not-null="true" />
</property>
</class>
</hibernate-mapping>而你的程序里应该加一个sno的属性:public class StudentsDAO extends BaseHibernateDAO {
private static final Log log = LogFactory.getLog(StudentsDAO.class);
// property constants
public static final String SNAME = "sname";
public static final String PASSWORD = "password";
public String sno = "123456" public void save(Students transientInstance) {
log.debug("saving Students instance");
try {
getSession().save(transientInstance);
getSession().beginTransaction().commit();
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
出错的原因是因为你没有指定学号属性的值,因为你要自己不使用自增长主键,那你就必须在执行save方法前指定一个id的值,
这样就会成功了.
getSession().beginTransaction().commit();出错了
出错信息:
org.hibernate.exception.DataException: could not insert: [cn.edu.hhuc.hibernate.Students]
org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:77)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2078)
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2427)
org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:51)
org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:139)
org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:297)
org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
org.hibernate.impl.SessionImpl.flush(SessionImpl.java:985)
org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:333)
org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
cn.edu.hhuc.hibernate.StudentsDAO.save(StudentsDAO.java:28)
cn.edu.hhuc.struts.action.RegAction.execute(RegAction.java:66)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
如果开始事务的话,那在那开始啊,在什么时候提交呢,什么时候结束呢?
希望后详细一点的代码……
private static final Log log = LogFactory.getLog(StudentsDAO.class);
// property constants
public static final String SNAME = "sname";
public static final String PASSWORD = "password"; public void save(Students transientInstance) {
log.debug("saving Students instance");
Session session = getSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
session.save(transientInstance);
tx.commit();
session.close();
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
tx.rollback();
throw re;
}
}
你保存数据之前这个值要存在阿。
还是不行,仍然在commit()处出错:
org.hibernate.exception.DataException: could not insert: [cn.edu.hhuc.hibernate.Students]
org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:77)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2078)
org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2427)
org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:51)
org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:139)
org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:297)
org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
org.hibernate.impl.SessionImpl.flush(SessionImpl.java:985)
org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:333)
org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
cn.edu.hhuc.hibernate.StudentsDAO.save(StudentsDAO.java:45)
cn.edu.hhuc.struts.action.RegAction.execute(RegAction.java:66)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)to hanpoyangtitan
我的sno给了啊
RegAction.java
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) throws UnsupportedEncodingException {
RegForm regForm = (RegForm) form;// TODO Auto-generated method stub
String inSno = regForm.getSno().trim();
String inSname = regForm.getName().trim();
String inPassword = regForm.getPassword();
Integer sno = Integer.parseInt(inSno);
String sname = new String(inSname.getBytes("ISO-8859-1"),"GB2312");
String password = new String(inPassword);
StudentsDAO studentsDB = new StudentsDAO();
Students temp = studentsDB.findById(sno);
if (temp != null) {
System.out.println(temp.getSno());
System.out.println("Repeat register!");
return mapping.findForward("failure");
}
else {
Students student = new Students(sno, sname, password);
studentsDB.save(student);
System.out.println("Register success!");
return mapping.findForward("success");
}
}students.java
public Students(Integer sno, String sname, String password) {
super(sno, sname, password);
}AbstractStudents.java
public AbstractStudents(Integer sno, String sname, String password) {
this.sno = sno;
this.sname = sname;
this.password = password;
}
Struts1.2+Spring1.2+HIbernate3.1整合用户示例代码:http://download.csdn.net/source/323772
Struts2.0+Spring2.0+Hibernate3.1登录及增删改查的完整演示示例:http://download.csdn.net/source/326113我想这个应该对你有帮助的,你下了看下可能会找到你的错误.