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如何在JAVA中使用AJAX實現用戶登陸注冊驗證？很多新手對此不是很清楚，為了幫助大家解決這個難題，下面小編將為大家詳細講解，有這方面需求的人可以來學習下，希望你能有所收獲。
技術棧
JSP+Servlet+Oracle
具體代碼
JSP部分：
<%@ 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之外的其他瀏覽器使用ajax
} catch (tryMS) {
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");//ie瀏覽器適配
} catch (otherMS) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");//ie瀏覽器適配
} catch (failed) {
xmlHttp = null;
}
}
}
return xmlHttp;
}
//提交請求
var xmlHttp;
function checkUserExists() {
var u = document.getElementById("uname");
var username = u.value;
if (username == "") {
alert("請輸入用戶名");
u.focus();
return false;
}
//訪問字符串
var url = "loginServlet";
//創建核心xmlhttprequest組件
xmlHttp = createXMLHttpRequest();
//設置回調函數
xmlHttp.onreadystatechange = proessRequest;
//初始化核心組件
xmlHttp.open("post", url, true);
//設置請求頭
xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;");
//發送請求
xmlHttp.send("uname="+username);
}
//回調函數
function proessRequest() {
if (xmlHttp.status==200 && xmlHttp.readyState == 4) {
var b = xmlHttp.responseText;//得到服務端的輸出結果
if (b=="true") {
document.getElementById("alert").innerHTML = "<font color='red'>用戶名已經存在！</font>";
}else {
document.getElementById("alert").innerHTML = "<font color='blue'>用戶名可以使用！</font>";
}
}
}
</script>
<body>
請輸入用戶名：
<input id="uname" name="uname" type="text" onblur="checkUserExists()" /><div id="alert" ></div>
</body>
</html>這里沒有用Dao層，直接用servlet和service層進行驗證。
下面是service下JDBC查詢的代碼：
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查詢用戶名是否存在
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語句
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連接代碼：
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();
}
}
}關于user類：
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;
}關于控制層servlet：
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");//獲取到輸入的用戶名
boolean isUname = ajaxService.searchUser(uname);//調用service中的查詢方法
response.setCharacterEncoding("UTF-8");//設置字符編碼
PrintWriter out = response.getWriter();
out.print(isUname);
out.flush();
out.close();//關閉資源
}
/**
* @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);
}
}看完上述內容是否對您有幫助呢？如果還想對相關知識有進一步的了解或閱讀更多相關文章，請關注億速云行業資訊頻道，感謝您對億速云的支持。
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