登陆界面(jsp)客户端验证

[html] 
<pre class="html" name="code">第二步：通过servlet处理</pre><pre class="html" name="code"> </pre><pre class="html" name="code"> </pre><pre class="html" name="code">import java.io.IOException; 
import java.io.PrintWriter; 
import java.util.ArrayList; 
import java.util.List; 
 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
 
public class validateServlet extends HttpServlet { 
 
    public void doGet(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, IOException { 
            //获得用户的信息 
        String username=req.getParameter("username"); 
        String password=req.getParameter("password"); 
        String repassword=req.getParameter("repassword"); 
        String shuoming=req.getParameter("shuoming");//说明 
        String []sex=req.getParameterValues("sex");//获得性别 
        String []aihao=req.getParameterValues("aihao");//获得兴趣 
        String []add=req.getParameterValues("add");//获得地址 
         
 
         
        //String repassword=req.getParameter("repassword"); 
        //String repassword=req.getParameter("repassword"); 
         
        List<String> list=new ArrayList<String>(); 
        List<String> xingqu=new ArrayList<String>(); 
        if (null=="username"||"".equals(username)) 
        { 
            list.add("there can't be a blank!");             
        } 
        if (password==null||password.length()<6||password.length()>10)