AJAX实例应用-1（注册时判断用户名是否存在）

最新推荐文章于 2021-08-05 19:50:04 发布

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#ajax #import #null #user #xmlhttprequest #input

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本文介绍了一个简单的用户注册系统实现，包括前端验证和后端处理。通过JavaScript进行用户名唯一性检查，并使用JSP完成用户数据的存储。

1.首先附上我的注册页面源码。（这其中的User类没有很好的封装及分层，大家凑合着看，我会在最后贴上User的源码，中间的那段JavaScript是重中之重）：

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>

<%@ page import="com.ycringfinger.shopping.*" %>

request.setCharacterEncoding("GB18030");

String action = request.getParameter("action");

if(action!=null && action.equals("register")){

String username = request.getParameter("username");

String password = request.getParameter("password");

String phone = request.getParameter("phone");

String addr = request.getParameter("addr");

User u = new User();

u.setUsername(username);

u.setPassword(password);

u.setPhone(phone);

u.setAddr(addr);

u.setRdate(new Date(System.currentTimeMillis()));

u.save();

return;

}

<html>

<head>

var req;

function validate() {

var idField = document.getElementById("username");

var url = "validate.jsp?username=" + escape(idField.value);

if(window.XMLHttpRequest) {

req = new XMLHttpRequest();

} else if (window.ActiveXObject) {

req = new ActiveXObject("Microsoft.XMLHTTP");

}

req.open("GET", url, true);

req.onreadystatechange = callback;

req.send(null);

}

function callback() {

if(req.readyState == 4) {

if(req.status == 200) {

var msg = req.responseXML.getElementsByTagName("msg")[0];

setMsg(msg.childNodes[0].nodeValue)

}

function setMsg(msg) {

if(msg == "valid") {

document.getElementById("usermsg").innerHTML = "<font color='green'>恭喜你，该用户名尚未注册</font>"

} else if(msg == "invalid") {

document.getElementById("usermsg").innerHTML = "<font color='red'>该用户名已注册</font>"

}

</script>

</head>

<body>

<form name="form" action="register.jsp" method="post"

onSubmit="return checkdata()">

<tr>

<td>

用户名:

</td>

<td>

</td>

</tr>

<tr>

<td>

密码:

</td>

<td>

</td>

</tr>

<tr>

<td>

密码确认:

</td>

<td>

</td>

</tr>

<tr>

<td>

电话:

</td>

<td>

</td>

</tr>

<tr>

<td>

地址:

</td>

<td>

</td>

</tr>

<tr>

<td>

</td>

</tr>

</table>

</form>

</body>

</html>

2.validate.jsp的源码如下（注意前面那几个设置属性如setContentType,setHeader等是必需的）：

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>

<%@ page import="com.ycringfinger.shopping.*" %>

response.setContentType("text/xml");

response.setHeader("Cache-Control", "no-store");

response.setHeader("Pragma", "no-cache");

response.setDateHeader("Expires", 0);

request.setCharacterEncoding("GB18030");

String userName = request.getParameter("username").trim();

if(User.userExists(userName)) {

response.getWriter().write("<msg>valid</msg>");

} else {

response.getWriter().write("<msg>invalid</msg>");

}

3.本人的User.java：（大家不要笑话）

package com.ycringfinger.shopping;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.sql.Timestamp;

import java.util.ArrayList;

import java.util.Date;

import java.util.Iterator;

import java.util.List;

import com.ycringfinger.shopping.util.*;

public class User {

private int id;

private String username;

private String password;

private String phone;

private String addr;

private Date rdate;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

public String getPhone() {

return phone;

}

public void setPhone(String phone) {

this.phone = phone;

}

public String getAddr() {

return addr;

}

public void setAddr(String addr) {

this.addr = addr;

}

public Date getRdate() {

return rdate;

}

public void setRdate(Date rdate) {

this.rdate = rdate;

}

public void save() {

Connection conn = DB.getConnection();

String sql = "insert into user values (null, ?, ?, ?, ?, ?)";

PreparedStatement pstmt = DB.getPreparedStatement(conn, sql);

try {

pstmt.setString(1, username);

pstmt.setString(2, password);

pstmt.setString(3, phone);

pstmt.setString(4, addr);

pstmt.setTimestamp(5, new Timestamp(rdate.getTime()));

pstmt.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();

} finally {

DB.closePreparedStatement(pstmt);

DB.closeConnection(conn);

}

public static List<User> getUsers() {

List<User> users = new ArrayList<User>();

Connection conn = null;

Statement stmt = null;

ResultSet rs = null;

try {

conn = DB.getConnection();

stmt = DB.getStatement(conn);

String sql = "select * from user";

rs = DB.executeQuery(stmt, sql);

while (rs.next()) {

User u = new User();

u.setId(rs.getInt(1));

u.setUsername(rs.getString("username"));

u.setPassword(rs.getString("password"));

u.setPhone(rs.getString("phone"));

u.setAddr(rs.getString("addr"));

u.setRdate(rs.getTimestamp("rdate"));

users.add(u);

}

} catch (SQLException e) {

e.printStackTrace();

} finally {

DB.closeResultSet(rs);

DB.closeStatement(stmt);

DB.closeConnection(conn);

}

return users;

}

public static void deleteUser(int id) {

Connection conn = null;

Statement stmt = null;

try {

conn = DB.getConnection();

stmt = DB.getStatement(conn);

stmt.executeUpdate("delete from user where id = " + id);

} catch (Exception e) {

e.printStackTrace();

} finally {

DB.closeStatement(stmt);

DB.closeConnection(conn);

}

public static User validate(String username, String password)

throws UserNotFoundException, PasswordNotCorrectException {

Connection conn = null;

String sql = "select * from user where username = '" + username + "'";

Statement stmt = null;

ResultSet rs = null;

User u = null;

try {

conn = DB.getConnection();

stmt = DB.getStatement(conn);

rs = DB.executeQuery(stmt, sql);

if (!rs.next()) {

throw new UserNotFoundException();

} else if (!rs.getString("password").trim().equals(password)) {

throw new PasswordNotCorrectException();

} else {

u = new User();

u.setId(rs.getInt("id"));

u.setUsername(rs.getString("username"));

u.setPassword(rs.getString("password"));

u.setPhone(rs.getString("phone"));

u.setAddr(rs.getString("addr"));

u.setRdate(rs.getTimestamp("rdate"));

}

} catch (SQLException e) {

e.printStackTrace();

} finally {

DB.closeResultSet(rs);

DB.closeStatement(stmt);

DB.closeConnection(conn);

}

return u;

}

public void update(){

Connection conn = DB.getConnection();

String sql = "update user set username = ?, phone = ?, addr = ? where id = " + this.id;

PreparedStatement pstmt = DB.getPreparedStatement(conn, sql);

try {

pstmt.setString(1, username);

pstmt.setString(2, phone);

pstmt.setString(3, addr);

pstmt.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();

} finally {

DB.closePreparedStatement(pstmt);

DB.closeConnection(conn);

}

public static boolean userExists(String userName) {

boolean b = true;

List<User> users = User.getUsers();

for(Iterator<User> it=users.iterator(); it.hasNext(); ) {

User u = it.next();

if(u.getUsername().equals(userName)) {

b = false;

}

return b;

}