hibernate 联合主键应用及配置用xml方式实现

复合（联合）主键映射    通常将复合主键相关的属性，单独放到一个类中  * 此类必须实现序列化接口 implements java.io.Serializable    * 覆写hashcode和equals方法    类：    import java.io.Serializable;    public classNamePK implements Serializable{ //主键类    private static final long serialVersionUID = 8313037022835155821L;    private String firstName;  private String lastName;    public String getFirstName() {     return firstName;  }  public void setFirstName(String firstName) {     this.firstName = firstName;  }  public String getLastName() {     return lastName;  }  public void setLastName(String lastName) {     this.lastName = lastName;  }    //重写，交给eclipse自己来写,source/generator hashCode() and equals()  public int hashCode() {     final int PRIME = 31;     int result = 1;     result = PRIME * result + ((firstName == null) ? 0 : firstName.hashCode());     result = PRIME * result + ((lastName == null) ? 0 : lastName.hashCode());     return result;  }    //重写，交给eclipse自己来写  public boolean equals(Object obj) {     if (this == obj)      return true;     if (obj == null)      return false;     if (getClass() != obj.getClass())      return false;     final NamePK other = (NamePK) obj;     if (firstName == null) {      if (other.firstName != null)       return false;     } else if (!firstName.equals(other.firstName))      return false;     if (lastName == null) {      if (other.lastName != null)       return false;     } else if (!lastName.equals(other.lastName))      return false;     return true;  }    }    public classUserInfo{  privateNamePK namePk;  private String sex;  private int age;    }    hbm.xml    UserInfo.hbm.xml    <?xml version="1.0" encoding="utf-8"?>  <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">  <hibernate-mapping package="com.zd.model">      <class name="UserInfo" table="user_info" >         <composite-id name="namePk">              <key-property name="firstName" column="first_name" length="12"/>              <key-property name="lastName" column="last_name" length="12"/>          </composite-id>          <property name="sex" length="12"/>          <property name="age" />      </class>    </hibernate-mapping>    测试用例：    public void testCompositeId(){     Session session = null;     Transaction ta = null;     try{      session = HibernateUtil.getSession();      ta = session.beginTransaction();       NamePK namePk = new NamePK();        namePk.setFirstName("Zhang");        namePk.setLastName("san");        UserInfo ui = new UserInfo();       ui.setNamePk(namePk);        ui.setSex("M");        ui.setAge(12);       session.save(ui);      ta.commit();     }catch(Exception e){      e.printStackTrace();      if(ta != null){       ta.rollback();      }     }finally{      //关闭session， user变为detached离线对象      HibernateUtil.closeSession(session);     }      }    public void testgetId(){     Session session = null;     Transaction ta = null;     try{      session = HibernateUtil.getSession();      ta = session.beginTransaction();        NamePK namePk = new NamePK();        namePk.setFirstName("Zhang");        namePk.setLastName("san");       UserInfo ui = (UserInfo) session.get(UserInfo.class, namePk); //get or load均是要序列化的类，所以要把主键implements Serializable        System.out.println(ui.getAge());        System.out.println(ui.getSex());            ta.commit();     }catch(Exception e){      e.printStackTrace();      if(ta != null){       ta.rollback();      }     }finally{      //关闭session， user变为detached离线对象      HibernateUtil.closeSession(session);     }      }