Java Web

我也不知道我错哪了
我想实现的功能是当用户输入用户名和密码时，后台获取，然后再SAE的云数据库中查询，返回true|false给前台
总是显示连接超时：
求大神指点！！
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
Caused by: java.net.ConnectException: Connection timed out: connect

public class ComputeService {
/**
* 获取数据库连接
*
* @param request
* @return
*/
private Connection getConn() {
String url = "jdbc:mysql://w.rdc.sae.sina.com.cn:3307/app_wwwite";
String user = "nwj5k4yoyw";
String password = "iywhj4jizmmxmw52hi3iz3yj140jzm53xy2hhjyi";
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url, user, password);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}

/**
* 操作数据库，比对该用户名和密码是否存在于数据库
*
* @param bean 包含用户名与密码
* @return true|false
* @throws java.sql.SQLException
*/
public boolean isExit(UserBean bean) throws SQLException {

String User_Name = bean.getA();
String User_Password = bean.getB();
String sql = "select password from binding where snum=?";

ResultSet rs = null;
try {
Connection conn = new ComputeService().getConn();
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, User_Name);
//执行查询并获取结果集
rs = ps.executeQuery();
//遍历查询结果集
while (rs.next()) {
return rs.getString("password").equals(User_Password);
}
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}