[求教]为什么小弟我在使用HashCodeBuilder在one-to-many关系中出现Lazy错误

2012-11-01

[求教]为什么我在使用HashCodeBuilder在one-to-many关系中出现Lazy异常最近遇到一个奇怪的问题，我在实体类

[求教]为什么我在使用HashCodeBuilder在one-to-many关系中出现Lazy异常
最近遇到一个奇怪的问题，我在实体类的基类中使用了org.apache.commons.lang.builder.HashCodeBuilder，然后在one-to-many关系映射(customer <---> order)中出现org.hibernate.LazyInitializationException: illegal access to loading collection异常。

小弟刚刚接触hibernate，这个问题找了两天才发现问题所在，但是仍然不知道为什么会这样，请大家不吝赐教。

环境：struts + hibernate3, hibernate2也试验过
异常：
org.hibernate.LazyInitializationException: illegal access to loading collection
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:341)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
at org.hibernate.collection.PersistentSet.hashCode(PersistentSet.java:411)
at org.apache.commons.lang.builder.HashCodeBuilder.append(HashCodeBuilder.java:392)
at org.apache.commons.lang.builder.HashCodeBuilder.reflectionAppend(HashCodeBuilder.java:353)
at org.apache.commons.lang.builder.HashCodeBuilder.reflectionHashCode(HashCodeBuilder.java:327)
at org.apache.commons.lang.builder.HashCodeBuilder.reflectionHashCode(HashCodeBuilder.java:194)
at cz.model.BaseObject.hashCode(BaseObject.java:78)
at org.apache.commons.lang.builder.HashCodeBuilder.append(HashCodeBuilder.java:392)
at org.apache.commons.lang.builder.HashCodeBuilder.reflectionAppend(HashCodeBuilder.java:353)
at org.apache.commons.lang.builder.HashCodeBuilder.reflectionHashCode(HashCodeBuilder.java:327)
at org.apache.commons.lang.builder.HashCodeBuilder.reflectionHashCode(HashCodeBuilder.java:194)
at cz.model.BaseObject.hashCode(BaseObject.java:78)
at java.util.HashMap.hash(HashMap.java:261)...

Hibernate 3 和 2 都是这个异常
只是2的异常描述是：net.sf.hibernate.LazyInitializationException: cannot access loading collection

程序片断：
BO基类 cz.model.BaseObject

abstract public class BaseObject implements Serializable {public BaseObject(){}    ...    public String toString() {        return ToStringBuilder.reflectionToString(this,                ToStringStyle.MULTI_LINE_STYLE);    }    public boolean equals(Object o) {        return EqualsBuilder.reflectionEquals(this, o);    }    //注释掉这个函数就不出现异常    public int hashCode() {        return HashCodeBuilder.reflectionHashCode(this);    }

cz.model.Customer继承BaseObject

public class Customer extends BaseObject implements Serializable {      ...}

cz.model.Order继承BaseObject

public class Order extends BaseObject implements Serializable {      ...}

映射文件

Customer.hbm.xml

<?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" ><hibernate-mapping>    <class name="cz.model.Customer" table="CUSTOMERS">        <id name="id" column="ID" type="long">            <generator         inverse="true"        lazy="true">        <key column="CUSTOMER_ID" />        <one-to-many name="code"><hibernate-mapping><class name="cz.model.Order" table="ORDERS"><id name="id" type="long" column="ID"><generator /></id>                  ....<many-to-one name="customer" column="CUSTOMER_ID"cascade="save-update"/></class></hibernate-mapping>

DAO实现类中的方法

public Customer getCustomerById(Long customerId) throws AppException {Session session = HibernateUtil.getSession();Transaction tx = null;try {tx = session.beginTransaction();Query query = session.createQuery("from Customer c where c.id=:id");query.setLong("id", customerId.longValue());Customer customer = (Customer)query.uniqueResult();Set orderset = customer.getOrders();                            //在这里会抛出上面说的异常，如果在BaseObject.java中去掉                                 //public int hashCode() 方法就会正常，这是为什么呢？？System.out.println("orderset size=" + orderset.size());tx.commit();return customer;} catch (Exception ex) {HibernateUtil.rollbackTransaction(tx);AppException.appError(ex).printStackTrace();throw AppException.appError(ex);} finally {HibernateUtil.closeSession(session);}}

请大家帮我解答一下这个问题，谢谢。

1 楼 surroad 2007-02-07 遇到类似的问题，请教高手 2 楼 yes100 2007-02-16 我也遇到了，这个问题 3 楼 jasongreen 2007-03-14 可以自己实现HashCodeBuilder 
 
<div class='code_title'>java 代码</div>
<div class='dp-highlighter'>
<div class='bar'>?</div>
<ol class='dp-j' start='1'>
 <li class='alt'>import?java.lang.reflect.Array;??</li>
 <li class=''>??</li>
 <li class='alt'>public?class?HashCodeBuilder?{??</li>
 <li class=''>????public?HashCodeBuilder()?{??</li>
 <li class='alt'>??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>????private?int?result?=?17;??</li>
 <li class='alt'>??</li>
 <li class=''>????public?HashCodeBuilder?append(boolean?field)?{??</li>
 <li class='alt'>????????result?=?37?*?result?+?(field???1?:?0);??</li>
 <li class=''>????????return?this;??</li>
 <li class='alt'>????}??</li>
 <li class=''>??</li>
 <li class='alt'>????public?HashCodeBuilder?append(byte?field)?{??</li>
 <li class=''>????????result?=?37?*?result?+?(int)?field;??</li>
 <li class='alt'>????????return?this;??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>????public?HashCodeBuilder?append(char?field)?{??</li>
 <li class='alt'>????????result?=?37?*?result?+?(int)?field;??</li>
 <li class=''>????????return?this;??</li>
 <li class='alt'>????}??</li>
 <li class=''>??</li>
 <li class='alt'>????public?HashCodeBuilder?append(short?field)?{??</li>
 <li class=''>????????result?=?37?*?result?+?(int)?field;??</li>
 <li class='alt'>????????return?this;??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>????public?HashCodeBuilder?append(int?field)?{??</li>
 <li class='alt'>????????result?=?37?*?result?+?field;??</li>
 <li class=''>????????return?this;??</li>
 <li class='alt'>????}??</li>
 <li class=''>??</li>
 <li class='alt'>????public?HashCodeBuilder?append(long?field)?{??</li>
 <li class=''>????????result?=?37?*?result?+?(int)?(field?^?(field?>>>?32));??</li>
 <li class='alt'>????????return?this;??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>????public?HashCodeBuilder?append(float?field)?{??</li>
 <li class='alt'>????????result?=?37?*?result?+?Float.floatToIntBits(field);??</li>
 <li class=''>????????return?this;??</li>
 <li class='alt'>????}??</li>
 <li class=''>??</li>
 <li class='alt'>????public?HashCodeBuilder?append(double?field)?{??</li>
 <li class=''>????????append(Double.doubleToLongBits(field));??</li>
 <li class='alt'>????????return?this;??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>????public?HashCodeBuilder?append(Object?field)?{??</li>
 <li class='alt'>????????if(field?==?null)??</li>
 <li class=''>????????????result?=?0;??</li>
 <li class='alt'>????????else?if?(field.getClass().isArray())?{??</li>
 <li class=''>????????????for?(int?i?=?Array.getLength(field)?-?1;?i?>=?0;?i--)?{??</li>
 <li class='alt'>????????????????append(Array.get(field,?i));??</li>
 <li class=''>????????????}??</li>
 <li class='alt'>????????}?else??</li>
 <li class=''>????????????append(field.hashCode());??</li>
 <li class='alt'>????????return?this;??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>????public?int?toHashCode()?{??</li>
 <li class='alt'>????????return?result;??</li>
 <li class=''>????}??</li>
 <li class='alt'>??????</li>
 <li class=''>????@Override??</li>
 <li class='alt'>????public?int?hashCode()?{??</li>
 <li class=''>????????return?result;??</li>
 <li class='alt'>????}??</li>
 <li class=''>??????</li>
 <li class='alt'>????@Override??</li>
 <li class=''>????public?String?toString()?{??</li>
 <li class='alt'>????????return?String.valueOf(result);??</li>
 <li class=''>????}??</li>
 <li class='alt'>??</li>
 <li class=''>}??</li>
</ol>
</div>

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[求教]为什么小弟我在使用HashCodeBuilder在one-to-many关系中出现Lazy错误