Hibernate的代碼生成的外鍵引用對象

Question

我使用Hibernate逆向工程...... 我有一個表的用戶。 我有食譜Recipe_FK - 到User.userId。

當我運行的代碼生成我得到了與用戶POJO文件：

private Set<?> recipeses = new HashSet<Object>(0); 

現在 - 幾個問題：1。 當我做session.load（User.class，用戶id）; 它會加入嗎？並從食譜表中獲取食譜？我不想那樣... 我可以手動刪除它嗎？ 我怎樣才能扭轉英格蘭。沒有得到這個「設置」參考參數的表？

（我喜歡做需要提高性能時，手動連接。）

這裏是的.hbm.xml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"> 
<!-- Generated Aug 26, 2011 10:56:44 AM by Hibernate Tools 3.4.0.CR1 --> 
<hibernate-mapping> 
<class catalog="yoavby2_icdb" name="com.icdb.data.Recipe" table="recipes"> 
    <id name="recipeid" type="int"> 
    <column name="recipeid"/> 
    <generator class="identity"/> 
    </id> 
    <many-to-one class="com.icdb.data.User" fetch="select" name="users"> 
    <column name="ownerid" not-null="true"/> 
    </many-to-one> 
    <property generated="never" lazy="false" name="releasedate" type="timestamp"> 
    <column length="19" name="releasedate" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="preparationtime" type="int"> 
    <column name="preparationtime" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="name" type="string"> 
    <column length="50" name="name" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="description" type="string"> 
    <column length="200" name="description"/> 
    </property> 
    <property generated="never" lazy="false" name="lastupdated" type="timestamp"> 
    <column length="19" name="lastupdated" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="servecount" type="java.lang.Integer"> 
    <column name="servecount"/> 
    </property> 
    <property generated="never" lazy="false" name="complete" type="boolean"> 
    <column name="complete" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="ratingOneStar" type="int"> 
    <column name="ratingOneStar" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="ratingTwoStar" type="int"> 
    <column name="ratingTwoStar" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="ratingThreeStar" type="int"> 
    <column name="ratingThreeStar" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="ratingFourStar" type="int"> 
    <column name="ratingFourStar" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="ratingFiveStar" type="int"> 
    <column name="ratingFiveStar" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="totalRating" type="float"> 
    <column name="totalRating" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="category" type="int"> 
    <column name="category" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="numOfViews" type="int"> 
    <column name="numOfViews" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="indexOfRecipeOfUser" type="int"> 
    <column name="indexOfRecipeOfUser" not-null="true"/> 
    </property> 
    <property generated="never" lazy="false" name="picUrl" type="string"> 
    <column length="200" name="picUrl" not-null="false"/> 
    </property> 
    <set fetch="select" inverse="true" lazy="true" 
    name="recipeingredientses" sort="unsorted" table="recipeingredients"> 
    <key> 
    <column name="recipeid" not-null="true"/> 
    </key> 
    <one-to-many class="com.icdb.data.RecipeIngredient"/> 
    </set> 
    <set fetch="select" inverse="true" lazy="true" name="recipereviewses" 
    sort="unsorted" table="recipereviews"> 
    <key> 
    <column name="recipeid" not-null="true"/> 
    </key> 
    <one-to-many class="com.icdb.data.RecipeReviews"/> 
    </set> 
    <set fetch="select" inverse="true" lazy="true" 
    name="recipeinstructionses" sort="unsorted" table="recipeinstructions"> 
    <key> 
    <column name="recipeid" not-null="true"/> 
    </key> 
    <one-to-many class="com.icdb.data.RecipeInstruction"/> 
    </set> 
    <property name="recipedifficulty" type="int"> 
    <column name="recipedifficulty" not-null="true" sql-type="INTEGER"/> 
    </property> 
</class> 
</hibernate-mapping> 




<?xml version="1.0"?> 
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 
<!-- Generated 20:18:59 15/02/2012 by Hibernate Tools 3.4.0.CR1 --> 
<hibernate-mapping> 
    <class name="com.icdb.data.User" table="users" catalog="yoavby2_icdb"> 
     <id name="userid" type="java.lang.Integer"> 
      <column name="userid" /> 
      <generator class="identity" /> 
     </id> 
     <property name="birthdate" type="string"> 
      <column name="birthdate" length="50" not-null="true" /> 
     </property> 
     <property name="password" type="string"> 
      <column name="password" length="100" not-null="true" /> 
     </property> 
     <property name="firstname" type="string"> 
      <column name="firstname" length="50" not-null="true" /> 
     </property> 
     <property name="lastname" type="string"> 
      <column name="lastname" length="50" not-null="true" /> 
     </property> 
     <property name="country" type="string"> 
      <column name="country" length="100" not-null="true" /> 
     </property> 
     <property name="email" type="string"> 
      <column name="email" length="100" not-null="true" /> 
     </property> 
     <property name="numOfRecipes" type="int"> 
      <column name="numOfRecipes" not-null="true" /> 
     </property> 
     <property name="picUrl" type="string"> 
      <column name="picUrl" length="200" /> 
     </property> 
     <set name="usermessagesesForSenderUserId" table="usermessages" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="senderUserId" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.Usermessages" /> 
     </set> 
     <set name="usermessagesesForUserId" table="usermessages" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="userId" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.Usermessages" /> 
     </set> 
     <set name="recipeses" table="recipes" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="ownerid" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.Recipe" /> 
     </set> 
     <set name="generaltipses" table="generaltips" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="authorid" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.GeneralTip" /> 
     </set> 
     <set name="usersesForFavUserId" table="userfavchefsync" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="userId" not-null="true" /> 
      </key> 
      <many-to-many entity-name="com.icdb.data.User"> 
       <column name="favUserId" not-null="true" /> 
      </many-to-many> 
     </set> 
     <set name="friendshiptablesForUserBId" table="friendshiptable" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="userB_Id" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.Friendshiptable" /> 
     </set> 
     <set name="usersesForUserId" table="userfavchefsync" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="favUserId" not-null="true" /> 
      </key> 
      <many-to-many entity-name="com.icdb.data.User"> 
       <column name="userId" not-null="true" /> 
      </many-to-many> 
     </set> 
     <set name="friendshiptablesForUserAId" table="friendshiptable" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="userA_Id" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.Friendshiptable" /> 
     </set> 
     <set name="userrecipessyncs" table="userrecipessync" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="userId" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.Userrecipessync" /> 
     </set> 
     <set name="recipereviewses" table="recipereviews" inverse="true" lazy="true" fetch="select"> 
      <key> 
       <column name="reviewerid" not-null="true" /> 
      </key> 
      <one-to-many class="com.icdb.data.RecipeReviews" /> 
     </set> 
    </class> 
</hibernate-mapping> 

約阿夫

Answer 1

看到這一行：

<set name="recipeses" table="recipes" inverse="true" lazy="true" fetch="select"> 

的lazy="true"屬性意味着，集將被延遲加載，當溜溜ü訪問：

User u = session.find(User.class, someId); // only load the data from the User table 
Set<Recipe> recipes = u.getRecipes(); // returns the set, which is not loaded yet 
int size = recipes.size(); // loads the recipes linked to the user from the database, and returns the size 

這是一個必知。在使用Hibernate之前閱讀Hibernate documentation，否則你的應用程序將會是一場災難。你必須瞭解它是如何工作的，以避免犯錯誤。

我強烈建議您爲映射使用註釋而不是XML。它更標準，更簡潔，並且更易於udnerstand。