StudentsDao.java

public int id;
  public String  sname;
  public String sgender ;
  public int sage;
  public int grade;
  public String smarriage;

StudentsTest.java 

String url="jdbc:mysql://localhost:3306/lz?useUnicode&chacter=utf8";
    
    try {
      
      Class.forName("com.mysql.jdbc.Driver");
      Connection conn = DriverManager.getConnection(url, "root", "12345678");
      
      String sql="select sname from students";
      PreparedStatement pstm = conn.prepareStatement(sql);
      ResultSet rs = pstm.executeQuery();
      List lists= new ArrayList<StudentsDao>();
      
      while(rs.next()) {
        StudentsDao st = new StudentsDao();
        st.sname=rs.getString("sname");
      lists.add(st);
    }
      
      for( int i = 0 ; i < lists.size(); i ++) {
        StudentsDao st = (StudentsDao) lists.get(i);
        System.out.println(st.sname);
      }
      rs.close(); //结果集
      pstm.close(); 
      conn.close(); //数据库连接
      
      //System.out.println(conn);
    } catch ( Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }