hibernate 对应关系

hibernate中的一对多关系

 

 

 

 

public class Country {

	private int id;
	private String name;
	private Set<Integer> provinceId;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Set<Integer> getProvinceId() {
		return provinceId;
	}
	public void setProvinceId(Set<Integer> provinceId) {
		this.provinceId = provinceId;
	}
}


<hibernate-mapping package="com.xiaonei.model">

    <class name="Country" table="country">
        <id name="id" column="id">
          <generator class="sequence">
             <param name="sequence">SEQ_COUNTRY</param>
          </generator>
        </id>
        <property name="name" />
        <set name="provinceId">
          <key>
            <column name="COUNTRYID"></column>
          </key>
          <one-to-many class="com.xiaonei.model.Province"/>
        </set>
    </class>
</hibernate-mapping>

 

public class Province {
	 private int  id;
	 private String name;
	 private int countryId;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getCountryId() {
		return countryId;
	}
	public void setCountryId(int countryId) {
		this.countryId = countryId;
	}
}


<hibernate-mapping package="com.xiaonei.model">

    <class name="Province" table="province">
        <id name="id" column="id">
          <generator class="sequence">
             <param name="sequence">SEQ_PROVINCE</param>
          </generator>
        </id>
        <property name="name" />
        <property name="countryId" />
    </class>
</hibernate-mapping>
 

 

一对多的时候，多的一方是主动方，在实体的对应关系中只需要设置一对多中的“一”的一方就可以了，在多的一方就不需要设置了。

   在我刚开始配置的时候，犯了这样一个错误，在多的一方也配置了一对一的关系，结果发生这样的异常

  <hibernate-mapping package="com.xiaonei.model">

   
    <class name="Province" table="province">
        <id name="id" column="id">
          <generator class="sequence">
             <param name="sequence">SEQ_PROVINCE</param>
          </generator>
        </id>
        <property name="name" />

        <property name="countryId" />

        <one-to-one name="countryId"    class="com.xiaonei.model.Country"> </one-to-one>
    </class>
</hibernate-mapping>

发生了这样的异常：

严重: IllegalArgumentException in class: com.xiaonei.model.Province, setter method of property: countryId
2012-9-1 21:57:01 org.hibernate.property.BasicPropertyAccessor$BasicSetter set
严重: expected type: int, actual value: com.xiaonei.model.Country
Exception in thread "main" org.hibernate.PropertyAccessException:

Caused by: java.lang.IllegalArgumentException: argument type mismatch