功能说明 8 D {" Z( m1 m4 C" ^% Y4 f4 k8 v6 G. b 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。: A3 u# j. R' N. E0 N* }" D 接口 2 R, q2 a/ i, Q# W6 V public interface UserDao {
public User findName(String name);
}接口实现类 : C# w9 t2 L0 h 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 : E! a# S) O% u8 E0 i& D 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 & F/ ]% v+ ~% s <%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>AJAX实际操作注册验证用户名</title>
<script src="js/jquery-1.8.3.js"></script>
</head>
<body>
<form action="#" method="post">
<script type="text/javascript">
$(function () {
$("[name=userName]").blur(function () {
$.ajax({
type:"get",
url:"findName?name="+$("[name=userName]").val(),
dataType:"text",
success:function (data) {
//alert(data);
if (data=="1"){
$("#show").html("用户已存在！！！")
}else {
$("#show").html("用户名可用")
}
}
})
})
});
</script>
账号<input type="text" name="userName"><span id="show"></span></br>
密码<input type="password" name="password"></br>
<input type="submit" value="提交">
</form>
</body>
</html>数据库如下： - b* G7 {+ h2 u, E+ B* Z6 o
O" _- K/ x9 h0 b( X 运行结果如下： / W0 V3 G4 e4 V& k; p7 l
) B7 h& ~, O( v7 m S8 u. l1 |
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发表于 2021-4-10 23:05:56
