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数据加载中……

Hibernate之deleted object would be re-saved by cascade异常

在Hibernate中,删除存在关联关系的一个对象时,会出现 org.hibernate.ObjectDeletedException: deleted object would be re-saved by cascade (remove deleted object from associations)这个异常

如下:
持久化类:
import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
import org.apache.commons.lang.builder.ToStringBuilder;

/**
 * 产品类别对象
 * 
@author crazycy
 *
 
*/
public class ProductCategory extends BaseObject {

    
// Fields    

    
private long id;

    
private String name;

    
private String description;

    
private ProductCategory parentCategory;

    
private Set childrenCategories = new HashSet();

    
// Constructors

    
/** default constructor */
    
public ProductCategory() {
    }

    
/** minimal constructor */
    
public ProductCategory(String name) {
        
this.name = name;
    }
    
    
public ProductCategory(String name, String description) {
        
this.name = name;
        
this.description = description;
    }

    
/** full constructor */
    
public ProductCategory(String name, String description,
            ProductCategory parentCategory) {
        
this.name = name;
        
this.description = description;
        
this.parentCategory = parentCategory;
    }

    
/** full constructor */
    
public ProductCategory(String name, String description,
            Set childrenCategories) {
        
this.name = name;
        
this.description = description;
        
this.childrenCategories = childrenCategories;
    }

    
// Property accessors

    
public long getId() {
        
return this.id;
    }

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

    
public String getName() {
        
return this.name;
    }

    
public void setName(String name) {
        
this.name = name;
    }

    
public String getDescription() {
        
return this.description;
    }

    
public void setDescription(String description) {
        
this.description = description;
    }

    
public ProductCategory getParentCategory() {
        
return this.parentCategory;
    }

    
public void setParentCategory(ProductCategory parentCategory) {
        
this.parentCategory = parentCategory;
    }
    
    
/**
     * 由主来调:是主添加
     * 
@param productCategory
     
*/
    
public void addCategory(ProductCategory productCategory) {
        productCategory.setParentCategory(
this);
        childrenCategories.add(productCategory);
    }
    
    
/**
     * 由主来调;是从主删除
     * 
@param productCategory
     
*/
    
public void removeCategory(ProductCategory productCategory) {
        childrenCategories.remove(productCategory);
        productCategory.setParentCategory(
null);
    }
    
    
public Set getChildrenCategories() {
        
return childrenCategories;
    }

    
public void setChildrenCategories(Set childrenCategories) {
        
this.childrenCategories = childrenCategories;
    }

    
/**
     * 
@see java.lang.Object#equals(Object)
     
*/
    
public boolean equals(Object object) {
        
if (!(object instanceof ProductCategory)) {
            
return false;
        }
        ProductCategory rhs 
= (ProductCategory) object;
        
return new EqualsBuilder().append(this.description, rhs.description)
                .append(
this.name, rhs.name).append(this.id, rhs.id).isEquals();
    }

    
/**
     * 
@see java.lang.Object#hashCode()
     
*/
    
public int hashCode() {
        
return new HashCodeBuilder(1009592109-669108101).append(
                
this.description).append(this.name).append(this.id)
                .toHashCode();
    }

    
/**
     * 
@see java.lang.Object#toString()
     
*/
    
public String toString() {
        
return new ToStringBuilder(this).append("name"this.name).append(
                
"description"this.description).append("id"this.id)
                .toString();
    }

}

映射文件
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="">
    
<class name="ProductCategory" table="productcategory">
        
<id name="id" type="long">
            
<column name="ID" />
            
<generator class="native" />
        
</id>
        
<property name="name" type="string">
            
<column name="name" length="50" not-null="true" />
        
</property>
        
<property name="description" type="string">
            
<column name="description" length="150" />
        
</property>
        
<set name="childrenCategories" cascade="save-update" inverse="true">
            
<key column="parent"/>
            
<one-to-many class="ProductCategory"/>
        
</set>
        
<many-to-one name="parentCategory" column="parent" 
            
class="ProductCategory" 
            cascade
="save-update"
         
>
        
</many-to-one>
    
</class>
</hibernate-mapping>

测试代码:
category2.getChildrenCategories().remove(category5);
        category5.setParentCategory(
null);
        dao.removeProductCategory(category5.getId());

解决方案如下:
方法1 删除Set方的cascade
方法2 解决关联关系后,再删除 :
category2.getChildrenCategories().remove(category5);
        category5.setParentCategory(
null);
        dao.removeProductCategory(category5.getId());
方法3 在many-to-one方增加cascade 但值不能是none

如果以上三个方案都失败(哼哼~ 我用了5个小时才找出来的)
检查一下hashCode equals是否使用了id作为唯一标示的选项了;我用uuid.hex时是没有问