您的xml文件不遵循任何模式，因此只能依赖其根元素名称和格式良好的事实。下面将其Map到通用 Package 器对象，然后对其进行处理以生成属性对象列表：

public class JAXBAttribute {
    public static void main(String[] args) throws JAXBException {
        JAXBContext context = JAXBContext.newInstance(new Class[] {Wrapper.class});
        Wrapper wrapper = (Wrapper)context.createUnmarshaller().unmarshal(Thread.currentThread().getContextClassLoader().getResourceAsStream("wrapper.xml"));
        final Map<String,String> attributeTypeMap = new HashMap<String,String>();
        for(final AttributeTypeMapEntry entry : wrapper.getEntryList()) {
            attributeTypeMap.put(entry.getKey(), entry.getValue());
        }
        for(final Attribute a : wrapper.getAttributeObjectList()) {
            a.setType(attributeTypeMap.get(a.getRef()));
        }
        System.out.println(wrapper.getAttributeObjectList());
    }
}
@XmlRootElement(name="wrapper")
@XmlAccessorType(XmlAccessType.NONE)
class Wrapper {
    @XmlElement(name="attrName")
    private List<Attribute> attributeObjectList;
    @XmlElement(name="attrType")
    private List<AttributeTypeMapEntry> entryList;
    public List<Attribute> getAttributeObjectList() {
        return attributeObjectList;
    }
    public List<AttributeTypeMapEntry> getEntryList() {
        return entryList;
    }
}
@XmlAccessorType(XmlAccessType.NONE)  // Only annotated fields will be mapped
class AttributeTypeMapEntry {
    @XmlAttribute(name="attrRef")
    private String key;
    @XmlValue
    private String value;
    public String getKey() {
        return key;
    }
    public void setKey(String key) {
        this.key = key;
    }
    public String getValue() {
        return value;
    }
    public void setValue(String value) {
        this.value = value;
    }
    @Override
    public String toString() {
        return "AttributeTypeMapEntry [key=" + key + ", value=" + value + "]";
    }
}
@XmlAccessorType(XmlAccessType.NONE) // Only annotated fields will be mapped
class Attribute {
    @XmlValue
    private String name;
    private String type;
    @XmlAttribute(name="ref")
    private String ref;
    public String  getName() {
        return name;
    }
    public void setName(String name) {
        this.name= name;
    }
    public String getRef() {
        return ref;
    }
    public void setRef(String ref) {
        this.ref= ref;
    }
    public String  getType() {
        return type;
    }
    public void setType(String type) {
        this.type= type;
    }
    @Override
    public String toString() {
        return "Attribute [name=" + name + ", type=" + type + ", ref=" + ref + "]";
    }
}

这是同一任务的另一个解决方案。其思想是将初始文档转换为直接Mapxml形式，同时解析所有引用，然后将生成的xmlMap到java对象。
数据的xslt是：

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" indent="yes"/>
    <xsl:template match="/wrapper">
        <xsl:variable name="root" select="."/>
        <xsl:copy>
            <xsl:for-each select="attrName">
                <xsl:variable name="ref" select="@ref"></xsl:variable>
                <attribute>
                    <name><xsl:value-of select="text()"/></name>
                    <ref><xsl:value-of select="$ref"/></ref>
                    <type><xsl:value-of select="$root/attrType[@attrRef=$ref]/text()"/></type>
                </attribute>
            </xsl:for-each>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="text()"/>
</xsl:stylesheet>

直接Mapxml如下所示：

<?xml version="1.0" encoding="utf-8"?>
<wrapper>
   <attribute>
      <name>xxx</name>
      <ref>a</ref>
      <type>xxx</type>
   </attribute>
   <attribute>
      <name>xxx</name>
      <ref>b</ref>
      <type>xxx</type>
   </attribute>
   <attribute>
      <name>xxx</name>
      <ref>c</ref>
      <type/>
   </attribute>
</wrapper>

带有注解的代码如下：

public class JAXBAttribute {
    public static void main(String[] args) throws Exception {
        // Transform initial XML resolving all references, resulting in an straight-to-map XML
        final Transformer t = TransformerFactory.newInstance().newTransformer(
            new StreamSource(Thread.currentThread().getContextClassLoader().getResourceAsStream("wrapper.xsl")));
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        t.transform(
            new StreamSource(Thread.currentThread().getContextClassLoader().getResourceAsStream("wrapper.xml")), 
            new StreamResult(baos));
        // Create Java objects from a straight-to-map XML
        JAXBContext context = JAXBContext.newInstance(new Class[] {Wrapper.class});
        Wrapper wrapper = (Wrapper)context.createUnmarshaller().unmarshal(new ByteArrayInputStream(baos.toByteArray()));
        //
        System.out.println(wrapper.getAttributeObjectList());
    }
}
@XmlRootElement(name="wrapper")
@XmlAccessorType(XmlAccessType.FIELD)
class Wrapper {
    @XmlElement(name="attribute")
    private List<Attribute> attributeObjectList;
    public List<Attribute> getAttributeObjectList() {
        return attributeObjectList;
    }
}
@XmlAccessorType(XmlAccessType.FIELD)
class Attribute {
    private String name;
    private String type;
    private String ref;
    public String  getName() {
        return name;
    }
    public void setName(String name) {
        this.name= name;
    }
    public String getRef() {
        return ref;
    }
    public void setRef(String ref) {
        this.ref= ref;
    }
    public String  getType() {
        return type;
    }
    public void setType(String type) {
        this.type= type;
    }
    @Override
    public String toString() {
        return "Attribute [name=" + name + ", type=" + type + ", ref=" + ref + "]";
    }
}

注意本例中的所有文件都保存在类路径根目录中。