private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
Connection conn=DBUtil.getConnection();
Statement stmt=null;
try{
stmt=conn.createStatement();
String sql="select * from user";
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
if(jTextField1.getText().equals(rs.getString("username"))){
JOptionPane.showMessageDialog(null,"该用户名已经存在，不可以使用。");
}else if(jTextField1.getText().equals("")){
JOptionPane.showMessageDialog(null,"用户名不能为空，请重新填写！");
}else if(!jTextField1.getText().equals(rs.getString("username"))){
JOptionPane.showMessageDialog(null,"该用户名不存在，可以使用。");
}
}
}catch(SQLException e){
e.printStackTrace();
}finally{
try{
stmt.close();
DBUtil.close(conn);
}catch(SQLException e){
e.printStackTrace();
}
}
}
这里的while语句对信息提示框(出现次数)有影响，能�
org.apache.jasper.JasperException: Unable to compile class for JSP:
An error occurred at line: 52 in the jsp file: /vip_info.jsp
ÕË cannot be resolved
49: <table border="1& ......
