<tree name="sharedTree">
        <node id="1" label="SHARED_1" href="?label=SHARED_1">
            <node id="6" label="SHARED_6" href="?label=SHARED_6">
                <node id="7" label="SHARED_7" href="?label=SHARED_7">
                    <node id="8" label="SHARED_8" href="?label=SHARED_8">
                        <node id="9" label="SHARED_9" href="?label=SHARED_9">
                            <node id="10" label="SHARED_10" href="?label=SHARED_10"/>
                        </node>
                    </node>
                </node>
            </node>
        </node>
    </tree>
想要生成如上面所示的xml文件 请问怎么实现 ,一般想到用回调机制 ,但是java怎么实现回调机制呢  请高手帮我个忙!!