IBATIS 复杂类型属性（即自定义类型的属性）问题各位帮帮小弟,搞了好久没有找到问题原因

小弟做一个用户和地址的关联查询,就是用户表里面用一个  ADDRESSID 和 地址表里的一个 ID进行关联
domain  User 类里有一个 address类的属性 如下
public class User {
   /** @pdOid bc66dbcf-5b84-4673-a9f8-fe17a8b07387 */
   private java.lang.String id;
   /** @pdOid 47caf74d-6d89-4d94-9746-608859015ec4 */
   private java.lang.String name;
   /** @pdOid 07c34ea6-5ae1-464a-92b3-e36d888fadd5 */
   private Address address;
  

  
   /** @pdOid 6d6129f5-9fdd-496e-8436-9a0dfb2c8efe */
   public java.lang.String getId() {
      return id;
   }
  
   /** @param newId
    * @pdOid 53d4304a-f789-4f7d-ad22-0aef4e20949c */
   public void setId(java.lang.String newId) {
      id = newId;
   }
  
   /** @pdOid 612a03d8-3b1b-4d2b-bd24-30015821ae97 */
   public java.lang.String getName() {
      return name;
   }
  
   /** @param newName
    * @pdOid 338694a9-9ccf-49aa-a960-3a84cfa91e82 */
   public void setName(java.lang.String newName) {
      name = newName;
   }

public Address getAddress() {
return address;
}

public void setAddress(Address address) {
this.address = address;
}


public class Address {
   /** @pdOid 33ce27ec-a4d1-42a9-9cdd-4bba14c0ee79 */
   private java.lang.String id;
   /** @pdOid e4d9b0f7-d8b5-40c1-b6fb-f8376c1ca34e */
   private java.lang.String addname;
  
   /** @pdRoleInfo migr=no name=User assc=association1 mult=1..1 type=Composition */
   public User user;
  
   /** @pdOid c6be2677-fd4e-446c-9995-3022e36c0171 */
   public java.lang.String getId() {
      return id;
   }
  
   /** @param newId
    * @pdOid 14928d3a-2953-4b2a-bd6c-b3b2d202c1ef */
   public void setId(java.lang.String newId) {
      id = newId;
   }
  
   /** @pdOid de1d8ee3-422c-4295-97b1-d36f6baf8ab0 */
   public java.lang.String getAddname() {
      return addname;
   }
  
   /** @param newAddname
    * @pdOid 3efc3bb5-9fed-479a-a58f-028eeb29349b */
   public void setAddname(java.lang.String newAddname) {
      addname = newAddname;
   }


1.配置文件如下
<sqlMap namespace="user">
 

 
  <typeAlias alias="user" type="com.yirong.ums.domain.User"/>
   <typeAlias alias="address" type="com.yirong.ums.domain.Address"/>
  
  <resultMap id="userResult" class="user">
     <result property="id" column="ID"/>
     <result property="name" column="NAME"/>
     <result property="address" column="ADDRESSID" select="user.retriveaddress" />
  </resultMap>
 
<resultMap id="addressResult" class="address">
     <result property="id" column="ID"/>
     <result property="addname" column="ADDNAME"/>
  </resultMap>
 
  <statement id="retriveuser" resultMap="userResult" parameterClass="string">
      select * from T_USER where ID=#value#
  </statement>
<statement id="retriveaddress" resultMap="addressResult" parameterClass="string" >
      select * from ADDRESS where ID=#value#
  </statement>
  </sqlMap>

为什么关联查询的时候就是查不了呢.?
我要通过 address 这个属性来关联查询就是查不了.
报出如下错误

java.lang.NullPointerException
at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.endTransaction(SqlMapExecutorDelegate.java:782)
at com.ibatis.sqlmap.engine.impl.SqlMapSessionImpl.endTransaction(SqlMapSessionImpl.java:176)
at com.ibatis.sqlmap.engine.impl.SqlMapClientImpl.endTransaction(SqlMapClientImpl.java:154)
at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.autoEndTransaction(SqlMapExecutorDelegate.java:883)
at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.queryForObject(SqlMapExecutorDelegate.java:573)
at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.queryForObject(SqlMapExecutorDelegate.java:541)
at com.ibatis.sqlmap.engine.impl.SqlMapSessionImpl.queryForObject(SqlMapSessionImpl.java:106)
at com.ibatis.sqlmap.engine.impl.SqlMapClientImpl.queryForObject(SqlMapClientImpl.java:83)
at com.ibatis.sqlmap.engine.mapping.result.loader.ResultLoader.getResult(ResultLoader.java:77)
at com.ibatis.sqlmap.engine.mapping.result.loader.EnhancedLazyResultLoader$EnhancedLazyResultLoaderImpl.loadObject(EnhancedLazyResultLoader.java:130)
at com.ibatis.sqlmap.engine.mapping.result.loader.EnhancedLazyResultLoader$EnhancedLazyResultLoaderImpl.invoke(EnhancedLazyResultLoader.java:113)
at com.yirong.ums.domain.Address$$EnhancerByCGLIB$$89dbf808.toString(<generated>)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at com.yirong.ums.service.UserTest.testRetriveUser(UserTest.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at org.springframework.test.ConditionalTestCase.runBare(ConditionalTestCase.java:69)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:128)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)