Ajax js 使用Ajax檢測使用者名稱是否存在

jsp頁面: Js代碼

1. <script type="text/javascript" language="javascript">   
2.         var xmlHttp = false;   
3.         try {   
4.             xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");   
5.         } catch (e) {   
6.             try {   
7.                 xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");   
8.             } catch (e2) {   
9.                 xmlHttp = false;   
10.             }   
11.         }   
12.         if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {   
13.             xmlHttp = new XMLHttpRequest();   
14.         }   
15.            
16.         //檢測使用者名稱是否存在   
17.         function callServerCheckUname() {   
18.             //通過GET方法請求，將請求封裝在URL中
      
19.             var uname = document.getElementById("u_name").value;   
20.             xmlHttp.open("POST", 'CheckUname?u_name='+uname);   
21.             //設定伺服器響應的處理方法   
22.             xmlHttp.onreadystatechange = updatePageCheckUname;   
23.             // 發送請求   
24.             xmlHttp.send(null);   
25.         }   
26.         function updatePageCheckUname() {   
27.             if (xmlHttp.readyState == 4) {   
28.                 var response = xmlHttp.responseText;   
29.                 if(response >= 1){   
30.                     alert("使用者名稱已存在!");   
31.                 }else{   
32.                     alert("可註冊!");   
33.                 }   
34.             }   
35.         }   
36.         </script>  

<script type="text/javascript" language="javascript">var xmlHttp = false;try {    xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");} catch (e) {    try {        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");    } catch (e2) {        xmlHttp = false;    }}if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {    xmlHttp = new XMLHttpRequest();}//檢測使用者名稱是否存在function callServerCheckUname() {    //通過GET方法請求，將請求封裝在URL中    var uname = document.getElementById("u_name").value;    xmlHttp.open("POST", 'CheckUname?u_name='+uname);    //設定伺服器響應的處理方法    xmlHttp.onreadystatechange = updatePageCheckUname;    // 發送請求    xmlHttp.send(null);}function updatePageCheckUname() {    if (xmlHttp.readyState == 4) {        var response = xmlHttp.responseText;        if(response >= 1){        alert("使用者名稱已存在!");        }else{        alert("可註冊!");        }    }}</script>

web.xml設定檔: Xml代碼

1. <servlet>  
2.     <servlet-name>CheckUname</servlet-name>  
3.     <servlet-class>servlet.AjaxCheckUname</servlet-class>  
4.   </servlet>  
5. <servlet-mapping>  
6.     <servlet-name>CheckUname</servlet-name>  
7.     <url-pattern>/CheckUname</url-pattern>  
8.   </servlet-mapping>  

<servlet>    <servlet-name>CheckUname</servlet-name>    <servlet-class>servlet.AjaxCheckUname</servlet-class>  </servlet><servlet-mapping>    <servlet-name>CheckUname</servlet-name>    <url-pattern>/CheckUname</url-pattern>  </servlet-mapping>

servlet頁面: Java代碼

1. public void doPost(HttpServletRequest request, HttpServletResponse response)   
2.             throws ServletException, IOException {   
3.         response.setContentType("text/html;charset=GB2312");   
4.         PrintWriter out = response.getWriter();   
5.         try {   
6.             String uname = request.getParameter("u_name");   
7.             RegistDAOImpl regDao = new RegistDAOImpl();   
8.             out.print(regDao.checkUname(uname)) ;   
9.         } catch (Exception e) {   
10.         }   
11.         out.flush();   
12.         out.close();   
13.     }  

public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=GB2312");PrintWriter out = response.getWriter();try {String uname = request.getParameter("u_name");RegistDAOImpl regDao = new RegistDAOImpl();out.print(regDao.checkUname(uname)) ;} catch (Exception e) {}out.flush();out.close();}

DAO實作類別: Java代碼

1. public int checkUname(String uname){   
2.         Connection conn = null;   
3.         PreparedStatement pstm = null;   
4.         ResultSet rs = null;   
5.         int success = 0;   
6.         String sql = "select u_name from u_info where u_name='"+uname+"' or u_mobtel='"+uname+"' or u_email='"+uname+"'";
     
7.         try {   
8.             conn = getConnection();   
9.             pstm = conn.prepareStatement(sql);   
10.             rs = pstm.executeQuery(sql);   
11.             if(rs.next()){   
12.                 success = 1;   
13.             }   
14.             return success;   
15.         } catch (Exception e) {   
16.             e.printStackTrace();   
17.         } finally {   
18.             try {   
19.                 conn.close();   
20.             } catch (Exception e) {   
21.                 e.printStackTrace();   
22.             }   
23.         }   
24.         return success;   
25.     }