DOM4j 修改和删除

XML文件

<?xml version="1.0" encoding="UTF-8"?>
<contactList>
    <contact id="1">
        <name>某某</name>
        <age>20</age>
        <phone>15426354785</phone>
        <qq>1024557455</qq>
    </contact>
    <contact id="2">
        <name>张三</name>
        <age>44</age>
        <phone>17854213658</phone>
        <qq>1024532584</qq>
    </contact>
</contactList>