<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+request.getContextPath()+"/"; %>如何使用传统方法异步验证用户名的唯一性
代码2demo1.jsp文件：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+request.getContextPath()+"/"; %>使用的servlet中的doGet方法
代码3demo2.jsp文件：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+request.getContextPath()+"/"; %>使用的servlet中的doPost方法
代码4AjaxCheckUserNameServlet.java文件：
package com.ghj.packagofserlet;
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;
public class AjaxCheckUserNameServlet extends HttpServlet {
private static final long serialVersionUID = 6387744976765210524L;
/**
* 处理demo1.jsp中异步验证
*
* @author GaoHuanjie
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
try{
response.setCharacterEncoding("UTF-8");
request.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
//System.out.println(1/0);//故意出现异常，以检查demo1.jsp中xmlHttpRequest.status!=200的分支语句是否可用
String userName=request.getParameter("userName");//获取“用户名”
System.out.println("处理demo1.jsp中异步验证，用户名为："+userName);
if ("admin".equals(userName)) {
out.print("1");//“1”表示用户名不可用。
} else {
out.print("2");//“2”表示用户名可用。
}
out.flush();
out.close();
}catch (Exception e) {
e.printStackTrace();
response.setStatus(405);
}
}
/**
* 处理demo2.jsp中异步验证
*
* @author GaoHuanjie
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
try{
response.setCharacterEncoding("UTF-8");
request.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
//System.out.println(1/0);//故意出现异常，以检查demo2.jsp中xmlHttpRequest.status!=200的分支语句是否可用
String userName=request.getParameter("userName");//获取“用户名”
System.out.println("处理demo2.jsp中异步验证，用户名为："+userName);
if ("admin".equals(userName)) {
out.print("1");//“1”表示用户名不可用。
} else {
out.print("2");//“2”表示用户名可用。
}
out.flush();
out.close();
}catch (Exception e) {
e.printStackTrace();
response.setStatus(405);
}
}
}
代码5web.xml文件：
<?xml version="1.0" encoding="UTF-8"?>AjaxCheckUserNameServlet com.ghj.packagofserlet.AjaxCheckUserNameServlet AjaxCheckUserNameServlet /AjaxCheckUserNameServletindex.jsp