检测用户名是否存在的问题 我用了以个button,用来点击检查用户名是否存在,但是不知道代码怎么写,求完整代码实例. 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 1.点击按钮。跳转到新的页面,把当前文本框内的用户名传到那个页面。。2.在那个页面,先接收传过来的用户名,然后去SQL执行查询。查询表内是否有相同名字的记录。你用的什么语言我都不知道。。代码还是自己写比较好。 <%@ page language="java" pageEncoding="GBK"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>My JSP 'MyJsp1.jsp' starting page</title> </head> <body> <form action="/JD/check" method="POST"> 用户名:<input type="text" id="name" name="name"><input type="submit" value="[检查用户名重否]"><em><%=request.getAttribute("msg")==null?"":request.getAttribute("msg")%></em> </form> </body></html>package csdn;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class CheckExist extends HttpServlet { /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */ public void init() throws ServletException { // Put your code here } protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String msg = ""; String name = req.getParameter("name"); if(name==null || name.trim().length()==0){ msg = "非法字符串,空字符串"; }else{ //去数据库查询 //如果查到 if(true){ msg = "用户名已存在!"; }else{ msg = "用户名可用!"; } } req.setAttribute("msg",msg); req.getRequestDispatcher("/MyJsp1.jsp").forward(req, resp); }}<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet> <servlet-name>DataTest</servlet-name> <servlet-class>csdn.DataTest</servlet-class> </servlet> <servlet> <servlet-name>CheckExist</servlet-name> <servlet-class>csdn.CheckExist</servlet-class> </servlet> <servlet-mapping> <servlet-name>DataTest</servlet-name> <url-pattern>/DataTest</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>CheckExist</servlet-name> <url-pattern>/check</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app> 表单应用感觉$.post比$.ajax好用 大家呢? SVG控件会遮挡div的问题 这个ajax相关新闻怎么没有反应呢? [转]介绍一组实用的组件库--zkjs 我佛山人 Validator v4.0 求救! 一个函数内,同一个变量被声明了2次,用于不同的元素,会冲突吗? 求助在javascript的Unload()事件里调用一段JSP代码或包含一个JSP的页面方法 如何设置用WB打印控件进行打印预览时只预览某个iframe,而不是整个页面? 使用WebBrowser控件,怎么才能把打印出来的头部的页数、和底部的文件地址去掉?急用, JS的一个比较奇怪的问题,据说是闭包导致的 js日历
<%@ page language="java" pageEncoding="GBK"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'MyJsp1.jsp' starting page</title>
</head>
<body>
<form action="/JD/check" method="POST">
用户名:<input type="text" id="name" name="name"><input type="submit" value="[检查用户名重否]"><em><%=request.getAttribute("msg")==null?"":request.getAttribute("msg")%></em>
</form>
</body>
</html>package csdn;
import java.io.IOException;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class CheckExist extends HttpServlet { /**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
} /**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String msg = "";
String name = req.getParameter("name");
if(name==null || name.trim().length()==0){
msg = "非法字符串,空字符串";
}else{
//去数据库查询
//如果查到
if(true){
msg = "用户名已存在!";
}else{
msg = "用户名可用!";
}
}
req.setAttribute("msg",msg);
req.getRequestDispatcher("/MyJsp1.jsp").forward(req, resp);
}}<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<servlet-name>DataTest</servlet-name>
<servlet-class>csdn.DataTest</servlet-class>
</servlet>
<servlet>
<servlet-name>CheckExist</servlet-name>
<servlet-class>csdn.CheckExist</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DataTest</servlet-name>
<url-pattern>/DataTest</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>CheckExist</servlet-name>
<url-pattern>/check</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>