Person object has setters and getters for Address and the Person mapping looks like this:

<one-to-one name="address" class="test.Address"
   cascade="save-update"
   outer-join="false"
   constrained="true"/>

CREATE TABLE PERSON (
       PERSON_ID           INTEGER NOT NULL,
       FIRST_NAME           VARCHAR2(30) NOT NULL,
       LAST_NAME            VARCHAR2(20) NOT NULL,
       SEX                  VARCHAR2(7) NOT NULL,
       BIRTH_DATE           DATE NOT NULL
);

ALTER TABLE PERSON
       ADD  ( PRIMARY KEY (PERSON_ID) ) ;


CREATE TABLE ADDRESS (
       ADDRESS_ID           INTEGER NOT NULL,
       ADDRESS1             VARCHAR2(40) NOT NULL,
       CITY                 VARCHAR2(40) NULL,
       STATE                VARCHAR2(30) NULL,
       ZIP                  INTEGER NULL,
       PERSON_ID           INTEGER NULL
);

ALTER TABLE ADDRESS
       ADD  ( PRIMARY KEY (ADDRESS_ID) ) ;

ALTER TABLE ADDRESS
       ADD  ( FOREIGN KEY (PERSON_ID)
                             REFERENCES PERSON
                             ON DELETE SET NULL ) ;

Person Mapping--------------------------------------
<hibernate-mapping>
<class name="test.Person" schema="Test" table="PERSON">

<id column="PERSON_ID" name="id" type="java.lang.Integer">
<generator class="sequence">
<param name="sequence">PERSON_SEQ</param>
</generator>
</id>

<property column="FIRST_NAME" length="30" name="firstName" not-null="true" type="string"/>
<property column="LAST_NAME" length="20" name="lastName" not-null="true" type="string"/>
<property column="SEX" length="7" name="sex" not-null="true" type="string"/>
<property column="BIRTH_DATE" length="7" name="birthDate" not-null="true" type="timestamp"/>
</class>
</hibernate-mapping>


Address Mapping----------------------------------------

<hibernate-mapping>
<class name="test.Address" schema="TEST" table="ADDRESS">

<id column="ADDRESS_ID" name="id" type="java.lang.Integer">
<generator class="sequence">
<param name="sequence">ADDRESS_SEQ</param>
</generator>
</id>

<property column="ADDRESS1" length="40" name="address1" not-null="true" type="string"/>
<property column="CITY" length="40" name="city" type="string"/>
<property column="STATE" length="30" name="state" type="string"/>
<property column="ZIP" length="22" name="zip" type="java.lang.Integer"/>
<property column="PATIENT_ID" length="22" name="patientId" type="java.lang.Integer"/>

</class>
</hibernate-mapping>

public class Person {
    private Address address;
    // ...
}

<one-to-one name="address" class="test.Address" cascade="all" constrained="true"/>