需求
通过ajax异步刷新页面验证用户输入的账号密码是否在数据库中存在。
技术栈
jsp+servlet+oracle
具体代码
jsp部分：
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<%@ page language="java" contenttype="text/html; charset=utf-8" pageencoding="utf-8"%><!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd"><html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"><title>insert title here</title></head><script> function createxmlhttprequest() { try { xmlhttp = new xmlhttprequest();//除了ie之外的其他浏览器使用ajax } catch (tryms) { try { xmlhttp = new activexobject("msxml2.xmlhttp");//ie浏览器适配 } catch (otherms) { try { xmlhttp = new activexobject("microsoft.xmlhttp");//ie浏览器适配 } catch (failed) { xmlhttp = null; } } } return xmlhttp; } //提交请求 var xmlhttp; function checkuserexists() { var u = document.getelementbyid("uname"); var username = u.value; if (username == "") { alert("请输入用户名"); u.focus(); return false; } //访问字符串 var url = "loginservlet"; //创建核心xmlhttprequest组件 xmlhttp = createxmlhttprequest(); //设置回调函数 xmlhttp.onreadystatechange = proessrequest; //初始化核心组件 xmlhttp.open("post", url, true); //设置请求头 xmlhttp.setrequestheader("content-type","application/x-www-form-urlencoded;"); //发送请求 xmlhttp.send("uname="+username); } //回调函数 function proessrequest() { if (xmlhttp.status==200 && xmlhttp.readystate == 4) { var b = xmlhttp.responsetext;//得到服务端的输出结果 if (b=="true") { document.getelementbyid("alert").innerhtml = "<font color='red'>用户名已经存在！</font>"; }else { document.getelementbyid("alert").innerhtml = "<font color='blue'>用户名可以使用！</font>"; } } }</script><body> 请输入用户名： <input id="uname" name="uname" type="text" onblur="checkuserexists()" /><div id="alert" style="display:inline"></div></body></html> |
这里没有用dao层，直接用servlet和service层进行验证。
下面是service下jdbc查询的代码：
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import java.sql.connection;import java.sql.resultset;import java.sql.sqlexception;import java.sql.statement;import com.stx.service.user;import com.stx.service.connectionmanager;public class ajaxservice { public boolean searchuser (string uname) { //jdbc查询用户名是否存在 boolean isfalse = false; connection connection = null; statement stmt = null; resultset rs = null; connection = connectionmanager.getconnection(); try { stmt = connection.createstatement(); string sql = "select * from user_b where uname='"+uname+"'";//sql语句 rs = stmt.executequery(sql); isfalse=rs.next(); } catch (sqlexception e) { e.printstacktrace(); } finally { connectionmanager.closeresultset(rs); connectionmanager.closestatement(stmt); connectionmanager.closeconnection(connection); } return isfalse; }} |
jdbc连接代码：
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import java.sql.connection;import java.sql.drivermanager;import java.sql.resultset;import java.sql.sqlexception;import java.sql.statement;public class connectionmanager { private final static string driver_class = "oracle.jdbc.oracledriver"; private final static string url = "jdbc:oracle:thin:@localhost:1521:orcl"; private final static string dbname = "ibook"; private final static string password = "qwer"; public static connection getconnection() { connection connection = null; try { class.forname(driver_class); connection = drivermanager.getconnection(url, dbname, password); } catch (classnotfoundexception e) { e.printstacktrace(); } catch (sqlexception e) { e.printstacktrace(); } return connection; } public static void closeresultset(resultset rs) { try { if (rs != null) rs.close(); } catch (sqlexception e) { e.printstacktrace(); } } public static void closeconnection(connection connection) { try { if (connection != null && !connection.isclosed()) connection.close(); } catch (sqlexception e) { e.printstacktrace(); } } public static void closestatement(statement stmt) { try { if (stmt != null) stmt.close(); } catch (sqlexception e) { e.printstacktrace(); } }} |
关于user类：
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public class user { private string uname; public user() { super(); } public user(string uname) { super(); this.uname = uname; } public string getuname() { return uname; } public void setuname(string uname) { this.uname = uname; } |
关于控制层servlet：
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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.stx.service.ajaxservice;/** * servlet implementation class loginservlet */public class loginservlet extends httpservlet { private static final long serialversionuid = 1l; private ajaxservice ajaxservice = new ajaxservice(); /** * @see httpservlet#httpservlet() */ public loginservlet() { super(); // todo auto-generated constructor stub } /** * @see httpservlet#doget(httpservletrequest request, httpservletresponse response) */ protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { request.setcharacterencoding("utf-8"); string uname = request.getparameter("uname");//获取到输入的用户名 boolean isuname = ajaxservice.searchuser(uname);//调用service中的查询方法 response.setcharacterencoding("utf-8");//设置字符编码 printwriter out = response.getwriter(); out.print(isuname); out.flush(); out.close();//关闭资源 } /** * @see httpservlet#dopost(httpservletrequest request, httpservletresponse response) */ protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception { // todo auto-generated method stub doget(request, response); }} |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://segmentfault.com/a/1190000015150083
