Hibernate关联关系映射(单向篇)

Hibernate关联关系可分为单向关联和双向关联两大类。单向关联可以分为一对一、一对多、多对一和多对多4种关联方式，而多向关联可以分为一对一、一对多和多对多3种关联方式。 Hibernate连接管理类HibernateUtil.java public class HibernateUtil { private st

Hibernate关联关系可分为单向关联和双向关联两大类。单向关联可以分为一对一、一对多、多对一和多对多4种关联方式，而多向关联可以分为一对一、一对多和多对多3种关联方式。

Hibernate连接管理类HibernateUtil.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> HibernateUtil {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> SessionFactory sessionFactory;

    <span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> final ThreadLocal<Session> threadLocal = <span class="hljs-keyword">new</span> ThreadLocal<Session>();

    <span class="hljs-keyword">static</span>{
        <span class="hljs-keyword">try</span>{
            Configuration cfg = <span class="hljs-keyword">new</span> Configuration().configure();
            sessionFactory = cfg.buildSessionFactory();
        }<span class="hljs-keyword">catch</span>(Throwable ex){
            <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> ExceptionInInitializerError(ex);
        }
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> SessionFactory <span class="hljs-title">getSessionFactory</span>(){
        <span class="hljs-keyword">return</span> sessionFactory;
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> Session <span class="hljs-title">getSession</span>() throws HibernateException{
        Session session = (Session)threadLocal.<span class="hljs-keyword">get</span>();
        <span class="hljs-keyword">if</span>(session == <span class="hljs-keyword">null</span> || !session.isOpen()){
            session = (sessionFactory != <span class="hljs-keyword">null</span>)?sessionFactory.openSession():<span class="hljs-keyword">null</span>;
            threadLocal.<span class="hljs-keyword">set</span>(session);
        }

        <span class="hljs-keyword">return</span> session;
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">closeSession</span>() throws HibernateException{
        Session session = (Session)threadLocal.<span class="hljs-keyword">get</span>();
        threadLocal.<span class="hljs-keyword">set</span>(<span class="hljs-keyword">null</span>);
        <span class="hljs-keyword">if</span>(session != <span class="hljs-keyword">null</span>){
            session.close();
        }
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">shutdown</span>(){
        getSessionFactory().close();
    }

}</code>

1.单向的一对一关联

（1）通过主键关联

通过主键关联，是指两个数据表之间通过主键建立一对一的关联关系。这两张表的主键值是相同的，一张表改动时，另一张也会相关的发生改变，从而避免多余字段被创建，但基于主键关联的持久化类(其对应的数据表称为从表)不能拥有自己的主键生成策略，它的主键由关联类负责生成。另外，增加one-to-one元素来关联属性，必须为one-to-one元素增加constrained=”true”属性，表明该类主键由关联类生成。

示例：

实体类：

User.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> User {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> userid;
    <span class="hljs-keyword">private</span> String name;
    <span class="hljs-keyword">private</span> String password;
    <span class="hljs-keyword">private</span> Address address;
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getUserid</span>() {
        <span class="hljs-keyword">return</span> userid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setUserid</span>(<span class="hljs-keyword">int</span> userid) {
        <span class="hljs-keyword">this</span>.userid = userid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getName</span>() {
        <span class="hljs-keyword">return</span> name;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setName</span>(String name) {
        <span class="hljs-keyword">this</span>.name = name;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getPassword</span>() {
        <span class="hljs-keyword">return</span> password;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setPassword</span>(String password) {
        <span class="hljs-keyword">this</span>.password = password;
    }
    <span class="hljs-keyword">public</span> Address <span class="hljs-title">getAddress</span>() {
        <span class="hljs-keyword">return</span> address;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddress</span>(Address address) {
        <span class="hljs-keyword">this</span>.address = address;
    }
}</code>

Address.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> Address {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> addressid;
    <span class="hljs-keyword">private</span> String addressinfo;
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getAddressid</span>() {
        <span class="hljs-keyword">return</span> addressid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressid</span>(<span class="hljs-keyword">int</span> addressid) {
        <span class="hljs-keyword">this</span>.addressid = addressid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getAddressinfo</span>() {
        <span class="hljs-keyword">return</span> addressinfo;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressinfo</span>(String addressinfo) {
        <span class="hljs-keyword">this</span>.addressinfo = addressinfo;
    }


}</code>

表结构：

user表：

address表：

配置文件：

User.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.User"</span> table=<span class="hljs-string">"user"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"id"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"user_id"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"foreign"</span>>
                <param <span class="hljs-property">name</span>=<span class="hljs-string">"property"</span>>address</param>
            </generator>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"name"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"name"</span>>
        </<span class="hljs-keyword">property</span>>
        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"password"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"password"</span>>
        </<span class="hljs-keyword">property</span>>
        <one-<span class="hljs-keyword">to</span>-one <span class="hljs-property">name</span>=<span class="hljs-string">"address"</span> <span class="hljs-type">class</span>=<span class="hljs-string">"Address"</span> constrained=<span class="hljs-string">"true"</span>></one-<span class="hljs-keyword">to</span>-one>

    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

Address.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.Address"</span> table=<span class="hljs-string">"address"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"addressid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressinfo"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"addressinfo"</span>>
        </<span class="hljs-keyword">property</span>>


    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

测试类Test.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> Test {
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span>(String[] args){
        Session session = HibernateUtil.getSession();
        Transaction tx = session.beginTransaction();

        User u = <span class="hljs-keyword">new</span> User();
        u.setName(<span class="hljs-string">"sbw"</span>);
        u.setPassword(<span class="hljs-string">"123"</span>);

        Address a = <span class="hljs-keyword">new</span> Address();
        a.setAddressinfo(<span class="hljs-string">"heu"</span>);
        u.setAddress(a);

        session.save(a);
        session.save(u);
        tx.commit();

        HibernateUtil.closeSession();

    }
}</code>

运行结果：

（2）通过外键关联

通过外键关联时两张数据表的主键是不同的，通过在一张表中添加外键列来保持一对一的关系。配置外键关联关系时需要使用many-to-one元素。因为通过外键关联的一对一关系，本质上是多对一关系的特例。因此，只需在many-to-one元素中增加unique=“true”属性即可，这相当于在多的一端增加了唯一性的约束，表示多的一端也必须是唯一的，这样就变成为单向的一对一关系了。

示例：

实体类与通过主键关联相同。

表结构：

user表

address表

配置文件：

User.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.User"</span> table=<span class="hljs-string">"user"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"userid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"userid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"name"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"name"</span>>
        </<span class="hljs-keyword">property</span>>
        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"password"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"password"</span>>
        </<span class="hljs-keyword">property</span>>

        <many-<span class="hljs-keyword">to</span>-one <span class="hljs-property">name</span>=<span class="hljs-string">"address"</span> <span class="hljs-type">class</span>=<span class="hljs-string">"com.entity.Address"</span> unique=<span class="hljs-string">"true"</span> column=<span class="hljs-string">"addressid"</span>></many-<span class="hljs-keyword">to</span>-one>

    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

Address.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.Address"</span> table=<span class="hljs-string">"address"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"addressid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressinfo"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"addressinfo"</span>>
        </<span class="hljs-keyword">property</span>>


    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

测试类与通过主键关联一样

运行结果：

2.单向一对多关联

单向的一对多关联映射关系主要是通过外键来关联的。一对多的关联映射是在表示多的一方的数据表中增加一个外键，并由“一”的一方指向“多”的一方。单向的一对多关联的持久化类里需要包含一个集合属性，在“一”的一方访问“多”的一方时，“多”的一方将以集合的形式来体现。

示例：

实体类：

User.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> User {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> userid;
    <span class="hljs-keyword">private</span> String name;
    <span class="hljs-keyword">private</span> String password;
    <span class="hljs-keyword">private</span> Set<Address> address = <span class="hljs-keyword">new</span> HashSet<Address>();

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getUserid</span>() {
        <span class="hljs-keyword">return</span> userid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setUserid</span>(<span class="hljs-keyword">int</span> userid) {
        <span class="hljs-keyword">this</span>.userid = userid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getName</span>() {
        <span class="hljs-keyword">return</span> name;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setName</span>(String name) {
        <span class="hljs-keyword">this</span>.name = name;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getPassword</span>() {
        <span class="hljs-keyword">return</span> password;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setPassword</span>(String password) {
        <span class="hljs-keyword">this</span>.password = password;
    }
    <span class="hljs-keyword">public</span> Set<Address> <span class="hljs-title">getAddress</span>() {
        <span class="hljs-keyword">return</span> address;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddress</span>(Set<Address> address) {
        <span class="hljs-keyword">this</span>.address = address;
    }
}</code>

Address.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> Address {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> addressid;
    <span class="hljs-keyword">private</span> String addressinfo;

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getAddressid</span>() {
        <span class="hljs-keyword">return</span> addressid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressid</span>(<span class="hljs-keyword">int</span> addressid) {
        <span class="hljs-keyword">this</span>.addressid = addressid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getAddressinfo</span>() {
        <span class="hljs-keyword">return</span> addressinfo;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressinfo</span>(String addressinfo) {
        <span class="hljs-keyword">this</span>.addressinfo = addressinfo;
    }
}</code>

表结构：

User表

Address表

配置文件

User.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.User"</span> table=<span class="hljs-string">"user"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"userid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"userid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"name"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"name"</span>>
        </<span class="hljs-keyword">property</span>>
        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"password"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"password"</span>>
        </<span class="hljs-keyword">property</span>>

        <<span class="hljs-keyword">set</span> <span class="hljs-property">name</span>=<span class="hljs-string">"address"</span> table=<span class="hljs-string">"address"</span> inverse=<span class="hljs-string">"false"</span> lazy=<span class="hljs-string">"true"</span>>
            <key>
                <column <span class="hljs-property">name</span>=<span class="hljs-string">"userid"</span>/>
            </key>

            <one-<span class="hljs-keyword">to</span>-many <span class="hljs-type">class</span>=<span class="hljs-string">"com.entity.User"</span>/>
        </<span class="hljs-keyword">set</span>>

    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

Address.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.Address"</span> table=<span class="hljs-string">"address"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"addressid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressinfo"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"addressinfo"</span>>
        </<span class="hljs-keyword">property</span>>


    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

测试代码

Test.java

<code class=" hljs avrasm">public class Test {
    public static void main(String[] args){
        Session session = HibernateUtil<span class="hljs-preprocessor">.getSession</span>()<span class="hljs-comment">;</span>
        Transaction tx = session<span class="hljs-preprocessor">.beginTransaction</span>()<span class="hljs-comment">;</span>

        User u = new User()<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setName</span>(<span class="hljs-string">"sbw"</span>)<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setPassword</span>(<span class="hljs-string">"123"</span>)<span class="hljs-comment">;</span>

        Address a = new Address()<span class="hljs-comment">;</span>
        a<span class="hljs-preprocessor">.setAddressinfo</span>(<span class="hljs-string">"heu"</span>)<span class="hljs-comment">;</span>
        Address a1 = new Address()<span class="hljs-comment">;</span>
        a1<span class="hljs-preprocessor">.setAddressinfo</span>(<span class="hljs-string">"hrb"</span>)<span class="hljs-comment">;</span>

        u<span class="hljs-preprocessor">.getAddress</span>()<span class="hljs-preprocessor">.add</span>(a)<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.getAddress</span>()<span class="hljs-preprocessor">.add</span>(a1)<span class="hljs-comment">;</span>

        session<span class="hljs-preprocessor">.save</span>(a)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(a1)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(u)<span class="hljs-comment">;</span>
        tx<span class="hljs-preprocessor">.commit</span>()<span class="hljs-comment">;</span>

        HibernateUtil<span class="hljs-preprocessor">.closeSession</span>()<span class="hljs-comment">;</span>

    }
}</code>

运行结果：

3.单向的多对一关联

单向的多对一关联映射关系也是通过外键来关联的。多对一的映射方式类似于一对多的映射方式，不过它的映射关系是由“多”的一方指向“一”的一方。在表示“多”的一方的数据表中增加一个外键来指向表示“一”的一方的数据表，“一”的一方作为主表，”多“的一方作为从表。

示例：

实体类

User.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> User {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> userid;
    <span class="hljs-keyword">private</span> String name;
    <span class="hljs-keyword">private</span> String password;
    <span class="hljs-keyword">private</span> Address address = <span class="hljs-keyword">new</span> Address();

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getUserid</span>() {
        <span class="hljs-keyword">return</span> userid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setUserid</span>(<span class="hljs-keyword">int</span> userid) {
        <span class="hljs-keyword">this</span>.userid = userid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getName</span>() {
        <span class="hljs-keyword">return</span> name;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setName</span>(String name) {
        <span class="hljs-keyword">this</span>.name = name;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getPassword</span>() {
        <span class="hljs-keyword">return</span> password;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setPassword</span>(String password) {
        <span class="hljs-keyword">this</span>.password = password;
    }
    <span class="hljs-keyword">public</span> Address <span class="hljs-title">getAddress</span>() {
        <span class="hljs-keyword">return</span> address;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddress</span>(Address address) {
        <span class="hljs-keyword">this</span>.address = address;
    }
}</code>

Address.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> Address {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> addressid;
    <span class="hljs-keyword">private</span> String addressinfo;

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getAddressid</span>() {
        <span class="hljs-keyword">return</span> addressid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressid</span>(<span class="hljs-keyword">int</span> addressid) {
        <span class="hljs-keyword">this</span>.addressid = addressid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getAddressinfo</span>() {
        <span class="hljs-keyword">return</span> addressinfo;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressinfo</span>(String addressinfo) {
        <span class="hljs-keyword">this</span>.addressinfo = addressinfo;
    }
}</code>

表结构：

user表

address表

配置文件：

User.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.User"</span> table=<span class="hljs-string">"user"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"userid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"userid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"name"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"name"</span>>
        </<span class="hljs-keyword">property</span>>
        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"password"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"password"</span>>
        </<span class="hljs-keyword">property</span>>

        <many-<span class="hljs-keyword">to</span>-one <span class="hljs-property">name</span>=<span class="hljs-string">"address"</span> column=<span class="hljs-string">"addressid"</span>/>

    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

Address.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.Address"</span> table=<span class="hljs-string">"address"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"addressid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressinfo"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"addressinfo"</span>>
        </<span class="hljs-keyword">property</span>>


    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

测试类Test.java

<code class=" hljs avrasm">public class Test {
    public static void main(String[] args){
        Session session = HibernateUtil<span class="hljs-preprocessor">.getSession</span>()<span class="hljs-comment">;</span>
        Transaction tx = session<span class="hljs-preprocessor">.beginTransaction</span>()<span class="hljs-comment">;</span>

        User u = new User()<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setName</span>(<span class="hljs-string">"sbw"</span>)<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setPassword</span>(<span class="hljs-string">"123"</span>)<span class="hljs-comment">;</span>

        User u1 = new User()<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setName</span>(<span class="hljs-string">"gaoya"</span>)<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setPassword</span>(<span class="hljs-string">"456"</span>)<span class="hljs-comment">;</span>

        Address a = new Address()<span class="hljs-comment">;</span>
        a<span class="hljs-preprocessor">.setAddressinfo</span>(<span class="hljs-string">"heu"</span>)<span class="hljs-comment">;</span>

        u<span class="hljs-preprocessor">.setAddress</span>(a)<span class="hljs-comment">;</span>
        u1<span class="hljs-preprocessor">.setAddress</span>(a)<span class="hljs-comment">;</span>

        session<span class="hljs-preprocessor">.save</span>(a)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(u)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(u1)<span class="hljs-comment">;</span>
        tx<span class="hljs-preprocessor">.commit</span>()<span class="hljs-comment">;</span>

        HibernateUtil<span class="hljs-preprocessor">.closeSession</span>()<span class="hljs-comment">;</span>

    }
}</code>

测试结果:

4.单向的多对多关联

多对多关联在数据库中是比较常见的，它利用中间表将两个主表关联起来。中间表的作用是将两张表的主键作为其外键，通过外键建立这两张表的映射关系。在单向的多对多关联中，需要在主控端的类定义中增加一个Set集合属性，使得被关联一方的类的实例以集合的形式存在。

示例：

实体类：

User.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> User {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> userid;
    <span class="hljs-keyword">private</span> String name;
    <span class="hljs-keyword">private</span> String password;
    <span class="hljs-keyword">private</span> Set<Address> address = <span class="hljs-keyword">new</span> HashSet<Address>();

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getUserid</span>() {
        <span class="hljs-keyword">return</span> userid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setUserid</span>(<span class="hljs-keyword">int</span> userid) {
        <span class="hljs-keyword">this</span>.userid = userid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getName</span>() {
        <span class="hljs-keyword">return</span> name;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setName</span>(String name) {
        <span class="hljs-keyword">this</span>.name = name;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getPassword</span>() {
        <span class="hljs-keyword">return</span> password;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setPassword</span>(String password) {
        <span class="hljs-keyword">this</span>.password = password;
    }
    <span class="hljs-keyword">public</span> Set<Address> <span class="hljs-title">getAddress</span>() {
        <span class="hljs-keyword">return</span> address;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddress</span>(Set<Address> address) {
        <span class="hljs-keyword">this</span>.address = address;
    }
}</code>

Address.java

<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> Address {
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> addressid;
    <span class="hljs-keyword">private</span> String addressinfo;

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getAddressid</span>() {
        <span class="hljs-keyword">return</span> addressid;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressid</span>(<span class="hljs-keyword">int</span> addressid) {
        <span class="hljs-keyword">this</span>.addressid = addressid;
    }
    <span class="hljs-keyword">public</span> String <span class="hljs-title">getAddressinfo</span>() {
        <span class="hljs-keyword">return</span> addressinfo;
    }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAddressinfo</span>(String addressinfo) {
        <span class="hljs-keyword">this</span>.addressinfo = addressinfo;
    }
}</code>

表结构：

user表：

user_address表：

address表：

配置文件：

User.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.User"</span> table=<span class="hljs-string">"user"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"userid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"userid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"name"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"name"</span>>
        </<span class="hljs-keyword">property</span>>
        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"password"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"password"</span>>
        </<span class="hljs-keyword">property</span>>

        <<span class="hljs-keyword">set</span> <span class="hljs-property">name</span>=<span class="hljs-string">"address"</span> table=<span class="hljs-string">"user_address"</span>>
            <key column=<span class="hljs-string">"userid"</span>/>
            <many-<span class="hljs-keyword">to</span>-many column=<span class="hljs-string">"addressid"</span> <span class="hljs-type">class</span>=<span class="hljs-string">"com.entity.Address"</span>/>
        </<span class="hljs-keyword">set</span>>

    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

Address.hbm.xml

<code class=" hljs applescript"><hibernate-mapping>
    <<span class="hljs-type">class</span> <span class="hljs-property">name</span>=<span class="hljs-string">"com.entity.Address"</span> table=<span class="hljs-string">"address"</span>>
        <<span class="hljs-property">id</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressid"</span> type=<span class="hljs-string">"java.lang.Integer"</span> column=<span class="hljs-string">"addressid"</span>>
            <generator <span class="hljs-type">class</span>=<span class="hljs-string">"identity"</span>/>
        </<span class="hljs-property">id</span>>

        <<span class="hljs-keyword">property</span> <span class="hljs-property">name</span>=<span class="hljs-string">"addressinfo"</span> type=<span class="hljs-string">"java.lang.String"</span> column=<span class="hljs-string">"addressinfo"</span>>
        </<span class="hljs-keyword">property</span>>


    </<span class="hljs-type">class</span>>
</hibernate-mapping></code>

测试代码Test.java

<code class=" hljs avrasm">public class Test {
    public static void main(String[] args){
        Session session = HibernateUtil<span class="hljs-preprocessor">.getSession</span>()<span class="hljs-comment">;</span>
        Transaction tx = session<span class="hljs-preprocessor">.beginTransaction</span>()<span class="hljs-comment">;</span>

        User u = new User()<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setName</span>(<span class="hljs-string">"sbw"</span>)<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.setPassword</span>(<span class="hljs-string">"123"</span>)<span class="hljs-comment">;       </span>
        User u1 = new User()<span class="hljs-comment">;</span>
        u1<span class="hljs-preprocessor">.setName</span>(<span class="hljs-string">"gaoya"</span>)<span class="hljs-comment">;</span>
        u1<span class="hljs-preprocessor">.setPassword</span>(<span class="hljs-string">"456"</span>)<span class="hljs-comment">;</span>

        Address a = new Address()<span class="hljs-comment">;</span>
        a<span class="hljs-preprocessor">.setAddressinfo</span>(<span class="hljs-string">"heu"</span>)<span class="hljs-comment">;</span>
        Address a1 = new Address()<span class="hljs-comment">;</span>
        a1<span class="hljs-preprocessor">.setAddressinfo</span>(<span class="hljs-string">"hrb"</span>)<span class="hljs-comment">;</span>

        u<span class="hljs-preprocessor">.getAddress</span>()<span class="hljs-preprocessor">.add</span>(a)<span class="hljs-comment">;</span>
        u<span class="hljs-preprocessor">.getAddress</span>()<span class="hljs-preprocessor">.add</span>(a1)<span class="hljs-comment">;</span>
        u1<span class="hljs-preprocessor">.getAddress</span>()<span class="hljs-preprocessor">.add</span>(a)<span class="hljs-comment">;</span>
        u1<span class="hljs-preprocessor">.getAddress</span>()<span class="hljs-preprocessor">.add</span>(a1)<span class="hljs-comment">;</span>

        session<span class="hljs-preprocessor">.save</span>(a)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(a1)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(u)<span class="hljs-comment">;</span>
        session<span class="hljs-preprocessor">.save</span>(u1)<span class="hljs-comment">;</span>
        tx<span class="hljs-preprocessor">.commit</span>()<span class="hljs-comment">;</span>

        HibernateUtil<span class="hljs-preprocessor">.closeSession</span>()<span class="hljs-comment">;</span>

    }
}</code>

测试结果：