Hibernate Annotations(一)

Entity注释

@Entity
@BatchSize(size = 5)   //批处理
@Where(clause = "1=1")  //默认查询条件
@FilterDef(name = "minLength", parameters = ...{@ParamDef(name = "minLength", type = "integer")})  //过滤器
@Filters(...{
@Filter(name = "betweenLength"),
@Filter(name = "minLength", condition = ":minLength <= length")
        })
@org.hibernate.annotations.Table(appliesTo = "Forest",
        indexes = ...{@Index(name = "idx", columnNames = ...{"name", "length"})})  //建立索引
@Proxy(lazy = false)  //延迟加载
@Cache(usage = CacheConcurrencyStrategy.READ_ONLY)  //cache
public class ...
 

过滤器注释的使用

s.enableFilter( "betweenLength" ).setParameter( "minLength", 5 ).setParameter( "maxLength", 50 );
count = ( (Long) s.createQuery( "select count(*) from Forest" ).iterate().next() ).intValue();
assertEquals( 1, count );
s.disableFilter( "betweenLength" );
s.enableFilter( "minLength" ).setParameter( "minLength", 5 );
count = ( (Long) s.createQuery( "select count(*) from Forest" ).iterate().next() ).longValue();
assertEquals( 2l, count );
s.disableFilter( "minLength" );
Entity注释主要是添加在class的上面

Type注释
 

    @Type(type = "text") 
    public String getLongDescription() ...{
        return longDescription;
    }
    @Type(type = "caster")  //取值时转为小写
    public String getSmallText() ...{
        return smallText;
    }

    @Type(type = "caster", parameters = ...{@Parameter(name = "cast", value = "upper")})  //取值时转为大写
    public String getBigText() ...{
        return bigText;
    }
    @Lob  //二进制字段
    public Country getCountry() ...{
        return country;
    }
                     @Formula("maxAltitude * 1000")  //公式(数据库中并不存在这个字段)
    public long getMaxAltitudeInMilimeter() ...{
        return maxAltitudeInMilimeter;
    }
                     @Type(type = "org.hibernate.test.annotations.entity.MonetaryAmountUserType")  //CompositeType
    @Columns(columns = ...{
    @Column(name = "r_amount"),  //数据库字段
    @Column(name = "r_currency")  //数据库字段
                      })
CompositeType实现类

//$Id: MonetaryAmountUserType.java 11282 2007-03-14 22:05:59Z epbernard $
package org.hibernate.test.annotations.entity;

import java.io.Serializable;
import java.math.BigDecimal;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Currency;

import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.type.Type;
import org.hibernate.usertype.CompositeUserType;

/** *//**
 * @author Emmanuel Bernard
 */
public class MonetaryAmountUserType implements CompositeUserType ...{

    public String[] getPropertyNames() ...{
        return new String[]...{"amount", "currency"};
    }

    public Type[] getPropertyTypes() ...{
        return new Type[]...{Hibernate.BIG_DECIMAL, Hibernate.CURRENCY};
    }

    public Object getPropertyValue(Object component, int property) throws HibernateException ...{
        MonetaryAmount ma = (MonetaryAmount) component;
        return property == 0 ? (Object) ma.getAmount() : (Object) ma.getCurrency();
    }

    public void setPropertyValue(Object component, int property, Object value)
            throws HibernateException ...{
        MonetaryAmount ma = (MonetaryAmount) component;
        if ( property == 0 ) ...{
            ma.setAmount( (BigDecimal) value );
        }
        else ...{
            ma.setCurrency( (Currency) value );
        }
    }

    public Class returnedClass() ...{
        return MonetaryAmount.class;
    }

    public boolean equals(Object x, Object y) throws HibernateException ...{
        if ( x == y ) return true;
        if ( x == null || y == null ) return false;
        MonetaryAmount mx = (MonetaryAmount) x;
        MonetaryAmount my = (MonetaryAmount) y;
        return mx.getAmount().equals( my.getAmount() ) &&
                mx.getCurrency().equals( my.getCurrency() );
    }

    public int hashCode(Object x) throws HibernateException ...{
        return ( (MonetaryAmount) x ).getAmount().hashCode();
    }

    public Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner)
            throws HibernateException, SQLException ...{
        BigDecimal amt = (BigDecimal) Hibernate.BIG_DECIMAL.nullSafeGet( rs, names[0] );
        Currency cur = (Currency) Hibernate.CURRENCY.nullSafeGet( rs, names[1] );
        if ( amt == null ) return null;
        return new MonetaryAmount( amt, cur );
    }

    public void nullSafeSet(
            PreparedStatement st, Object value, int index,
            SessionImplementor session
    ) throws HibernateException, SQLException ...{
        MonetaryAmount ma = (MonetaryAmount) value;
        BigDecimal amt = ma == null ? null : ma.getAmount();
        Currency cur = ma == null ? null : ma.getCurrency();
        Hibernate.BIG_DECIMAL.nullSafeSet( st, amt, index );
        Hibernate.CURRENCY.nullSafeSet( st, cur, index + 1 );
    }

    public Object deepCopy(Object value) throws HibernateException ...{
        MonetaryAmount ma = (MonetaryAmount) value;
        return new MonetaryAmount( ma.getAmount(), ma.getCurrency() );
    }

    public boolean isMutable() ...{
        return true;
    }

    public Serializable disassemble(Object value, SessionImplementor session)
            throws HibernateException ...{
        return (Serializable) deepCopy( value );
    }

    public Object assemble(Serializable cached, SessionImplementor session, Object owner)
            throws HibernateException ...{
        return deepCopy( cached );
    }

    public Object replace(Object original, Object target, SessionImplementor session, Object owner)
            throws HibernateException ...{
        return deepCopy( original ); //TODO: improve
    }

}