【DRP】AJAX异步判断用户是否存在

 用户名 和提示：

<td width="78%">
     <input name="userId" type="text" class="text1" id="userId"
            size="10" maxlength="10" onkeypress="userIdOnKeyPress()" value="<%=userId %>" onblur="validate(this)">
     <span id="spanUserId"></span>
 </td>

 

 失去焦点的事件：

function validate(field) {
        //alert(document.getElementById("userId").value);
        //alert(field.value);
        if (trim(field.value).length != 0) {
            //创建Ajax核心对象XMLHttpRequest
            createXMLHttpRequest();
            
            var url = "user_validate.jsp?userId=" + trim(field.value) + "&time=" + new Date().getTime();
            
            //设置请求方式为GET，设置请求的URL，设置为异步提交
            xmlHttp.open("GET", url, true);
            
            //将方法地址复制给onreadystatechange属性
            //类似于电话号码
            xmlHttp.onreadystatechange=callback;
            
            //将设置信息发送到Ajax引擎
            xmlHttp.send(null);
        } else {
            document.getElementById("spanUserId").innerHTML = "";
        }    
    }

 

 

验证AJAX是否请求成功：

function callback() {
        //alert(xmlHttp.readyState);
        //Ajax引擎状态为成功
        if (xmlHttp.readyState == 4) {
            //HTTP协议状态为成功
            if (xmlHttp.status == 200) {
                if (trim(xmlHttp.responseText) != "") {
                    //通过span标签 提示用户信息
                    document.getElementById("spanUserId").innerHTML = "<font color='red'>" + xmlHttp.responseText + "</font>"
                }else {
                    document.getElementById("spanUserId").innerHTML = "";
                }
            }else {
                alert("请求失败，错误码=" + xmlHttp.status);
            }
        }
    }

 

 

接收  GET 请求传过来的值：

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<%@ page import="com.bjpowernode.drp.sysmgr.manager.*" %>      
<%
    //Thread.currentThread().sleep(5000);
    String userId = request.getParameter("userId");
    if (UserManager.getInstance().findUserById(userId) != null) {
        out.println("用户代码已经存在");
    }    
%>

 

 

调用底层方法查询数据库：

/**
     * 根据用户代码查询
     * @param userId
     * @return 如果存在返回User对象，否则返回null
     */
    public User findUserById(String userId) {
        String sql = "select user_id, user_name, password, contact_tel, email, create_date from t_user where user_id=?";
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        User user = null;
        try {
            conn = DbUtil.getConnection();
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, userId);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                user = new User();
                user.setUserId(rs.getString("user_id"));
                user.setUserName(rs.getString("user_name"));
                user.setPassword(rs.getString("password"));
                user.setContactTel(rs.getString("contact_tel"));
                user.setEmail(rs.getString("email"));
                user.setCreateDate(rs.getTimestamp("create_date"));
            }
        }catch(SQLException e) {
            e.printStackTrace();
        }finally {
            DbUtil.close(rs);
            DbUtil.close(pstmt);
            DbUtil.close(conn);
        }
        return user;
    }

 

连接数据库：

public static Connection getConnection() {

//如果不用XML文件 可以直接用下面注释掉的代码。
//        Connection conn = null;
//        try {
//            Class.forName("oracle.jdbc.driver.OracleDriver");
//            String url = "jdbc:oracle:thin:@localhost:1521:bjpowern";
//            String username = "drp1";
//            String password = "drp1";
//            conn = DriverManager.getConnection(url, username, password);
//        } catch (ClassNotFoundException e) {
//            e.printStackTrace();
//        } catch (SQLException e) {
//            e.printStackTrace();
//        }
//        return conn;

//读取XML文件中的连接数据库信息

        Connection conn = null;
        try {
            JdbcConfig jdbcConfig = XmlConfigReader.getInstance().getJdbcConfig();
            Class.forName(jdbcConfig.getDriverName());
            conn = DriverManager.getConnection(jdbcConfig.getUrl(), jdbcConfig.getUserName(), jdbcConfig.getPassword());
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

 

总结：让以后的开发变的高效起来！