实现了hibernate的简单的分页了。其实很简单（一）

本文介绍了一个基于Struts、Spring和Hibernate技术栈的分页功能实现过程，包括数据库表映射、DAO接口及其实现、以及服务层接口和实现等内容。

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今天终于实现了hibernate实现分页了。。把oksonic的SSH的例子做了增加，实现了查询的分页。

同时现在也把srtuts + spring + hibernate 结合的实现方法重新复习了一下，总结如下：

1 首先肯定是要把对应的数据库的表进行映射的，把影射类和表的映射XML文件放到包bo中：

包含文件AbstractUser.java User.java User.hbm.xml

表的映射配置文件如下：

<hibernate-mapping>
    <class name="com.oa.data.bo.User" table="userlist">
        <id name="id" type="integer">
            <column name="id" />
            <generator class="native"></generator>
        </id>
        <property name="userName" type="string">
            <column name="userName" length="100" not-null="true" />
        </property>
        <property name="userPwd" type="string">
            <column name="userPwd" length="100" not-null="true" />
        </property>
    </class>
</hibernate-mapping>

2 写DAO数据访问接口IUserDAO .java，放在dao包中：

package com.oa.data.dao;

import java.util.List;

import com.oa.data.bo.User;

public interface IUserDAO {

public abstract void save(User transientInstance);

public abstract void delete(User persistentInstance);

public abstract User findById(java.lang.Integer id);

public abstract List findByExample(User instance);

public abstract User merge(User detachedInstance);

public abstract void attachDirty(User instance);

public abstract void attachClean(User instance);

public abstract User findByUsername(String username);

public List findWithPage(int pageSize, int startRow);

public int counter();

}

3 写DAO数据访问实现类 UserDAO .java，放在dao.imp包中：

package com.oa.data.dao.impl;

import java.util.ArrayList;
import java.util.List;

import net.sf.hibernate.Transaction;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.LockMode;
import org.hibernate.criterion.Example;
import org.springframework.context.ApplicationContext;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

import com.oa.data.bo.User;
import com.oa.data.dao.IUserDAO;

/**
* Data access object (DAO) for domain model class User.
* @see .User
* @author MyEclipse - Hibernate Tools
*/
public class UserDAO extends HibernateDaoSupport implements IUserDAO {

private static final Log log = LogFactory.getLog(UserDAO.class);

protected void initDao() {
//do nothing
}

    /* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#save(com.oa.data.bo.User)
*/
    public void save(User transientInstance) {
        log.debug("saving User instance");
        try {
         this.getHibernateTemplate().saveOrUpdate(transientInstance);
            log.debug("save successful");
        } catch (RuntimeException re) {
            log.error("save failed", re);
            throw re;
        }
    }

/* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#delete(com.oa.data.bo.User)
*/
public void delete(User persistentInstance) {
        log.debug("deleting User instance");
        try {
            getHibernateTemplate().delete(persistentInstance);
            log.debug("delete successful");
        } catch (RuntimeException re) {
            log.error("delete failed", re);
            throw re;
        }
    }

    /* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#findById(java.lang.Integer)
*/
    public User findById( java.lang.Integer id) {
        log.debug("getting User instance with id: " + id);
        try {
            User instance = (User) getHibernateTemplate()
                    .get("User", id);
            return instance;
        } catch (RuntimeException re) {
            log.error("get failed", re);
            throw re;
        }
    }


    /* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#findByExample(com.oa.data.bo.User)
*/
    public List findByExample(User instance) {
        log.debug("finding User instance by example");
        try {
            List results = getSession()
                    .createCriteria("User")
                    .add(Example.create(instance))
            .list();
            log.debug("find by example successful, result size: " + results.size());
            return results;
        } catch (RuntimeException re) {
            log.error("find by example failed", re);
            throw re;
        }
    }

    /* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#merge(com.oa.data.bo.User)
*/
    public User merge(User detachedInstance) {
        log.debug("merging User instance");
        try {
            User result = (User) getHibernateTemplate()
                    .merge(detachedInstance);
            log.debug("merge successful");
            return result;
        } catch (RuntimeException re) {
            log.error("merge failed", re);
            throw re;
        }
    }

    /* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#attachDirty(com.oa.data.bo.User)
*/
    public void attachDirty(User instance) {
        log.debug("attaching dirty User instance");
        try {
            getHibernateTemplate().saveOrUpdate(instance);
            log.debug("attach successful");
        } catch (RuntimeException re) {
            log.error("attach failed", re);
            throw re;
        }
    }

    /* (non-Javadoc)
* @see com.oa.data.dao.impl.IUserDAO#attachClean(com.oa.data.bo.User)
*/
    public void attachClean(User instance) {
        log.debug("attaching clean User instance");
        try {
            getHibernateTemplate().lock(instance, LockMode.NONE);
            log.debug("attach successful");
        } catch (RuntimeException re) {
            log.error("attach failed", re);
            throw re;
        }
    }

public static IUserDAO getFromApplicationContext(ApplicationContext ctx) {
return (IUserDAO) ctx.getBean("UserDAO");
}

public User findByUsername(String username) {
log.debug("getting User instance with userName: " + username);
try {
   List list = getHibernateTemplate().find(
     "from User as u where userName = ?", username);
   if(list.size() > 0) {
    User instance = (User) list.get(0);
    return instance;
   } else {
    return null;
   }
} catch (RuntimeException re) {
   log.error("get failed", re);
   throw re;
}
}

public List findWithPage(int pageSize, int startRow) {
List list=new ArrayList();
Transaction tx = null;
log.debug("ShowAllUser");
try {
   org.hibernate.Query q ;
   q=this.getSessionFactory().openSession().createQuery("from User");
   q.setFirstResult(startRow);
   q.setMaxResults(pageSize);                                                 // hibernate简单分页的设置，设置起始行和每页的记录数
   list=q.list();

} catch (RuntimeException e) {
   // TODO Auto-generated catch block
          e.printStackTrace();
}

return list;
}

public int counter() {
int counter=0;
Transaction tx = null;
log.debug("counter");
counter = ((Integer)this.getHibernateTemplate().iterate("select count(*) from User").next()).intValue();
return counter;
}
}

4 因为用到了spring，需要做DAO服务代理，所以有必要实现服务类。service包中：

package com.oa.model.service;

import java.util.List;

import com.oa.data.bo.User;

public interface IUserService {
// 验证用户是否合法，并返回一个 User 对像
     public User isValidUser(String username,String password);
     public List findWithPage(int pageSize, int startRow);
     public int counter();
}

5 有服务接口就有实现类：service.imp包中：

package com.oa.model.service.impl;

import java.util.ArrayList;
import java.util.List;

import com.oa.data.bo.User;
import com.oa.data.dao.IUserDAO;
import com.oa.model.service.IUserService;

public class UserService implements IUserService {

private IUserDAO userDAO;

public IUserDAO getUserDAO() {
return userDAO;
}

public void setUserDAO(IUserDAO userDAO) {
this.userDAO = userDAO;
}

public User isValidUser(String username, String password) {
// TODO Auto-generated method stub
User user = userDAO.findByUsername(username);
if(user == null)
return null;
if(user.getUserPwd().equals(password))
return user;
return null;
}

public List findWithPage(int pageSize, int startRow) {
// TODO Auto-generated method stub
ArrayList list=new ArrayList();
list=(ArrayList) userDAO.findWithPage(pageSize,startRow);
return list;
}

public int counter() {
// TODO Auto-generated method stub
int counter=0;
counter=userDAO.counter();
return counter;
}

}