Hibernate沒有爲父/子關係進行延遲加載。相反，它在查詢

Question

2個SQL負載我有一個家長/孩子的關係是這樣的：

@Entity 
@Table(name = "Agent", schema = "dbo", catalog = "MyTime") 
public class Agent implements Serializable { 
    private Set<AgentAttr> attributes = new HashSet<AgentAttr>(); 

    @OneToMany 
    @JoinColumn(name="Agent_GUID") 
    public Set<AgentAttr> getAttributes() { 
     return attributes; 
    } 

    public void setAttributes(Set<AgentAttr> attributes) { 
     this.attributes = attributes; 
    } 
} 

這DAO調用是對代理進行查詢。

Query query = getSession().createQuery("from Agent where userName = :userName"); 
query.setParameter("userName", userName); 
List list = query.list(); 

該查詢將返回代理對象，並在列表的每個元素中加載屬性集合。 當檢查Hibernate日誌時，它顯示它執行2個SQL查詢，一個加載代理，第二個加載屬性， 。

因爲Hibernate文檔說延遲加載是默認行爲，所以我沒有想到這一點。 我希望查詢返回的屬性爲空。然後Hibernate只在調用Agent.getAttributes（）時加載它。 這就是延遲加載的重點，即只在需要時加載它，對嗎？我也試着明確地把@OneToMany（fetch = FetchType.LAZY）放在那裏，但是仍然一樣，不會執行延遲加載。

欣賞任何指示我可能做錯了什麼。謝謝。

下面是Hibernate的日誌：

2014/08/28 16:21:14.487 [DEBUG] <http-bio-8080-exec-3> (SqlStatementLogger.logStatement:109) - 
    /* 
from 
    Agent 
where 
    userName = :userName */ select 
     agent0_.Agent_GUID as Agent_GU1_1_, 
     agent0_.Address_Email as Address_2_1_, 
     agent0_.Address_SIP as Address_3_1_, 
     agent0_.Address_TEL as Address_4_1_, 
     agent0_.Address_XMPP as Address_5_1_, 
     agent0_.Company_GUID as Company_6_1_, 
     agent0_.Create_Tstamp as Create_T7_1_, 
     agent0_.Create_User as Create_U8_1_, 
     agent0_.Enabled as Enabled9_1_, 
     agent0_.First_Name as First_N10_1_, 
     agent0_.Last_Name as Last_Na11_1_, 
     agent0_.Location as Locatio12_1_, 
     agent0_.Password as Passwor13_1_, 
     agent0_.Role as Role14_1_, 
     agent0_.Security_Ans as Securit15_1_, 
     agent0_.Security_Q as Securit16_1_, 
     agent0_.Update_Tstamp as Update_17_1_, 
     agent0_.Update_User as Update_18_1_, 
     agent0_.User_Name as User_Na19_1_, 
     agent0_.Work_Status as Work_St20_1_ 
    from 
     MyTime.dbo.Agent agent0_ 
    where 
     agent0_.User_Name=? 
2014/08/28 16:21:14.487 [TRACE] <http-bio-8080-exec-3> (BasicBinder.bind:81) - binding parameter [1] as [VARCHAR] - [achansv@contactsolutions.com] 
2014/08/28 16:21:14.794 [TRACE] <http-bio-8080-exec-3> (BasicExtractor.extract:78) - extracted value ([Agent_GU1_1_] : [VARCHAR]) - [9E5537A6-96FF-4656-9F75-70B58E44C0E9] 
2014/08/28 16:21:20.632 [DEBUG] <http-bio-8080-exec-3> (SqlStatementLogger.logStatement:109) - 
    /* 
from 
    AgentAttr 
where 
    agentGuid = :agentGuid */ select 
     agentattr0_.Agent_Attr_GUID as Agent_At1_4_, 
     agentattr0_.Agent_GUID as Agent_GU2_4_, 
     agentattr0_.Attr_Category as Attr_Cat3_4_, 
     agentattr0_.Attr_Name as Attr_Nam4_4_, 
     agentattr0_.Attr_Value as Attr_Val5_4_, 
     agentattr0_.Create_Tstamp as Create_T6_4_, 
     agentattr0_.Create_User as Create_U7_4_, 
     agentattr0_.Enabled as Enabled8_4_, 
     agentattr0_.Location as Location9_4_, 
     agentattr0_.Update_Tstamp as Update_10_4_, 
     agentattr0_.Update_User as Update_11_4_ 
    from 
     MyTime.dbo.Agent_Attr agentattr0_ 
    where 
     agentattr0_.Agent_GUID=? 
2014/08/28 16:21:20.632 [TRACE] <http-bio-8080-exec-3> (BasicBinder.bind:81) - binding parameter [1] as [VARCHAR] - [9E5537A6-96FF-4656-9F75-70B58E44C0E9] 

Answer 1

根據規範中here：

懶惰的策略是提示的持久性提供運行時數據應該被延遲加載它是首當訪問。允許執行熱切地獲取已爲其指定了LAZY策略提示的數據。