日期:2014-05-16 浏览次数:20661 次
package com.wuliu.test; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.wuliu.dao.LoginDAO; public class ValidateName extends HttpServlet { public ValidateName(){ super(); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); LoginDAO dao = new LoginDAO(); boolean flag = false; String loginName=request.getParameter("loginName").toString(); flag = dao.userIsExist(loginName); if(true == flag) { response.getWriter().write("true");//此值jquery可以接收到 } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); } }
public boolean userIsExist(String loginId){ System.out.println("Enter userIsExist"); this.dao = new DBConnection(); this.cn = this.dao.getConnection(); // 根据指定用户名查询用户信息 String sql = "select * from LoginTable where LoginId='"+loginId+"'"; System.out.println("logid:"+loginId); try { // 获取PreparedStatement对象 this.ps = this.cn.prepareStatement(sql); // 对用户对象属性赋值 // ps.setString(1, loginId); // 执行查询获取结果集 rs = this.ps.executeQuery(); // 判断结果集是否有效 // System.out.println("rs.next()= "+rs.next()); if(false == rs.next()){ // 如果无效则证明此用户名可用 System.out.println("用户名可用"); return true; } // 释放此 ResultSet 对象的数据库和 JDBC 资源 rs.close(); // 释放此 PreparedStatement 对象的数据库和 JDBC 资源 ps.close(); } catch (SQLException e) { e.printStackTrace(); }finally{ // 关闭数据库连接 this.dao.closeConnection(cn); } System.out.println("用户名不可用"); return false; }