单例模式

package newdemo.jeno.designdemo.utlis;

/**
 * Created by songjiabin1 on 2016/9/12.
 */
public class Login {
    private static Login instance = null;

    public static Login getInstance() {
        if (instance == null) {
            synchronized (Login.class) {
                if (instance == null) {
                    instance = new Login();
                }
            }
        }
        return instance;
    }

}