java 读XML 文件

<?xml version="1.0" encoding="utf-8" ?>

<studentsdata>
  <ugstudents>
  <StudentNo>10193322</StudentNo>
  <Title>Ms.</Title>
  <FirstNames>Adwoa Ago</FirstNames>
  <Surname>Achampong</Surname>
  <Email>aaachampong@st.ug.edu.gh</Email>
  <Campus>Main</Campus>
  <Centre>Legon</Centre>
<Subjects>
<subjectCode>ENGL</subjectCode>
<subjectCode>dfdf</subjectCode>
</Subjects>
  </ugstudents>

  <ugstudents>
  <StudentNo>10211342</StudentNo>
  <Title>Mr.</Title>
  <FirstNames>Andrews Akwasi</FirstNames>
  <Surname>Acheampong</Surname>
  <Email>aaacheampong@st.ug.edu.gh</Email>
  <Campus>Main</Campus>
  <Centre>Legon</Centre>
<Subjects>
<subjectCode>ENGL</subjectCode>
<subjectCode>dfdf</subjectCode>
<subjectCode>dfdf</subjectCode>
</Subjects>
  </ugstudents>
</studentsdata>

文件格式如上，我在读取的时候