这篇文章主要为大家详细介绍了AJAX实现注册验证用户名，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
本文实例为大家分享了AJAX实现注册验证用户名的具体代码，供大家参考，具体内容如下
功能说明
当用户在注册页面输入用户名并且鼠标焦点离开输入框时，到数据表中去验证该用户名是否已经存在，如果存在提示不可用，否则，提示可用。
接口
public interface UserDao { public User findName(String name); }接口实现类
import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class UserDaoImpl implements UserDao { @Override public User findName(String name) { User user =null; Connection conn = DBHelper.getConn(); String sql = "select * from user where name=?"; try { PreparedStatement ps = conn.prepareStatement(sql); ps.setString(1,name); ResultSet rs = ps.executeQuery(); if (rs.next()){ user = new User(); user.setId(rs.getInt(1)); user.setName(rs.getString(2)); user.setPassword(rs.getString(3)); } } catch (SQLException e) { e.printStackTrace(); } return user; } }servlet
import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet("/findName") public class FindNameServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); String name = request.getParameter("name"); UserDao userDao = new UserDaoImpl(); User name1 = userDao.findName(name); if (name1!=null){ response.getWriter().write("1"); }else { response.getWriter().write("2"); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }JSP页面
< page contentType="text/html;charset=UTF-8" language="java"AJAX实际操作注册验证用户名
数据库如下：
运行结果如下：
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