hibernate分页查询的实现实例



hibernate分页查询的实现

Hirbernate  ,它自带分页API
例如:
Query q = sess.createQuery("from XXX");
q.setFirstResult(20);设置起始行
q.setMaxResults(10);每页条数
List cats = q.list(); //得到每页的数据

在mysql中新建数据好USER表,字段有3个,分别是id、username、password,贴上脚本仅供参考

create table `ding`.`user`(
`id` int default ” not null,
`username` varchar(30),
`password` varchar(30),
primary key (`id`)
);

切换到数据库透视图,新建一个mysql连接(这里就不再多说了)。

新建一个web工程,然后右键选择myeclipse,选择add hibernate…….. ,把hibernate的jar加入到工程中,选择的时候注意jar包要放在lib中,可以检查下,其中有一下会选择刚新建的mysql连接,加完以后就会看到SRC下多了一个hibernate.cfg.xml文件,内容包含了配置的连接信息,如下:
<?xml version=’1.0′ encoding=’UTF-8′?>
<!DOCTYPE hibernate-configuration PUBLIC
“-//Hibernate/Hibernate Configuration DTD 3.0//EN”
“http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd”>

<!– Generated by MyEclipse Hibernate Tools. –>
<hibernate-configuration>

<session-factory>
<property name=”connection.username”>root</property>
<property name=”connection.url”>
jdbc:mysql://localhost:3306/ding
</property>
<property name=”dialect”>
org.hibernate.dialect.MySQLDialect
</property>
<property name=”myeclipse.connection.profile”>mysql</property>
<property name=”connection.password”>ding</property>
<property name=”connection.driver_class”>
com.mysql.jdbc.Driver
</property>

</session-factory>

</hibernate-configuration>

切换到数据库透视图,启动那个连接找到建的USER表,右键选择Hibernate Reverse Engineering…,在弹出的框里面点击 Java src folder 一行最右侧的 Browser.. 按钮来选择源码目录,这里我选择自己工程src 目录,并把下面的 Java package 右侧的输入框中输入自己想要的包名,我这里是test,接着选中下面的复选框,我选前面两个:
[x] Hibernate mapping file (*.hbm.xml) for each database table
[x] Java Data Object (POJO <> DB Table)
第2项下面的复选create abstract class我这里不选,点击next,再在ID generator选择increment(自增长),点完成。

返回j2ee透视图,会看到在test包下生成了User.java和User.hbm.xml文件,如下:
public class User implements java.io.Serializable {

private Integer id;

private String username;

private String password;
public Integer getId() {
return this.id;
}

public void setId(Integer id) {
this.id = id;
}

public String getUsername() {
return this.username;
}


public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return this.password;
}

public void setPassword(String password) {
this.password = password;
}

}
<?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=”test.User” table=”user”>
<id name=”id” type=”java.lang.Integer”>
<column name=”id” />
<generator class=”increment” />
</id>
<property name=”username” type=”java.lang.String”>
<column name=”username” length=”30″ />
</property>
<property name=”password” type=”java.lang.String”>
<column name=”password” length=”30″ />
</property>
</class>
</hibernate-mapping>

同时在原先的hibernate.cfg.xml中加入了 <mapping resource=”test/User.hbm.xml” />,最终的hibernate.cfg.xml文件如下:
<?xml version=’1.0′ encoding=’UTF-8′?>
<!DOCTYPE hibernate-configuration PUBLIC
“-//Hibernate/Hibernate Configuration DTD 3.0//EN”
“http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd”>

<!– Generated by MyEclipse Hibernate Tools. –>
<hibernate-configuration>

<session-factory>
<property name=”connection.username”>root</property>
<property name=”connection.url”>
jdbc:mysql://localhost:3306/ding
</property>
<property name=”dialect”>
org.hibernate.dialect.MySQLDialect
</property>
<property name=”myeclipse.connection.profile”>mysql</property>
<property name=”connection.password”>ding</property>
<property name=”connection.driver_class”>
com.mysql.jdbc.Driver
</property>
<mapping resource=”test/User.hbm.xml” />

</session-factory>

</hibernate-configuration>

写个Test测试类

public class Test {

/**
* @Description 方法实现功能描述
* @param args
* void
* @throws 抛出异常说明
*/
public static void main(String[] args) {

SessionFactory sf = new Configuration().configure().buildSessionFactory();
Session session = sf.openSession();
String hql = “from User”;
int curpage = 1;//当前页
int pagesize = 2;//每页显示数
//以上两项有一项为0则查出所有记录
List list = findOnePage(session, hql, curpage, pagesize);
for(Iterator i = list.iterator();i.hasNext();){
User user = (User) i.next();
System.out.println(“username===”+user.getUsername());
}
}

public static List findOnePage(Session session,String strHQL, int offset, int pagesize){
List lst = null;
try {
Query query = session.createQuery(strHQL);
if (offset != 0 && pagesize != 0) {
query.setFirstResult((offset – 1) * pagesize);
query.setMaxResults(pagesize);
}
lst = query.list();
} catch (Exception ex) {
ex.printStackTrace();
}
return lst;
}

}

测试下就可以看到效果了
int curpage = 1;//当前页
int pagesize = 2;//每页显示数
可以改这两个参数试试

http://www.blogjava.net/laoding/articles/272015.html