初学者Servlet问题

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();

Connection conn=null;
PreparedStatement pstmt= null;
ResultSet rs=null;
String getname=request.getParameter("USERNAME");
String getpsw=request.getParameter("USERPSW");
try {
Class.forName("com.mysql.jdbc.driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost/db?"
+ "user=root&password=root");
pstmt=conn.prepareStatement("SELECT * FROM USERINFO WHERE UNAME=? AND UPSW=?");
pstmt.setString(1, getname);
pstmt.setString(2, getpsw);

rs = pstmt.executeQuery();
} catch (ClassNotFoundException e) {

e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
if(rs.next()){
response.sendRedirect("Welcome");
}
else {
response.sendRedirect("Login");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
out
.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println("  <BODY>");
out.print("   哈哈 "); out.println("  </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}