ajax jsp 实现动态验证

package cn.edu.bit.servlet; import java.io.IOException; import javax.servlet.ServletConfig; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class CheckServlet extends HttpServlet { public String[] usernameList; public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException { String username = (String)request.getParameter("username"); String password = (String)request.getParameter("password"); String repassword = (String)request.getParameter("repassword"); String email = (String)request.getParameter("email"); if(this.IsContain(username)) { request.setAttribute("error.message","您输入的用户名已经存在!"); RequestDispatcher requestDispatcher = request.getRequestDispatcher("error.jsp"); requestDispatcher.forward(request,response); }else { RequestDispatcher requestDispatcher = request.getRequestDispatcher("success.jsp"); requestDispatcher.forward(request,response); } } public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException { doGet(request,response); } public void init(ServletConfig config) throws ServletException { usernameList = new String[]{"Tom","Jerry","Brain"}; } public boolean IsContain(String param) { for(int i = 0; i <usernameList.length;i++) { if(usernameList[i].equals(param)) { return true; } else continue; } return false; } }