String xml=&quot；&lt；？xml version=&#92；&quot；1.0&#92；&quot；encoding=&#92；&quot；UTF-8&#92；&quot；standalone=&#92；&quot；yes&#92；&quot；？&gt；&lt；student&gt；&lt；classRoom&gt；&lt；className&gt；计算机&lt；/className&gt；&lt；id&gt；1&lt；/id&gt；&lt；/classRoom&gt；&lt；id&gt；1&lt；/id&gt；&lt；username&gt；zhangsan&lt；/username&gt；&lt；/student&gt；&quot。