abstract class和interface有什么区别?

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public abstract class BaseServlet extends HttpServlet
{
    public final void service(HttpServletRequest request, HttpServletResponse response) throws IOException,ServletException
    {
        //记录访问日志
        //进行权限判断
        if(具有权限)
        {
            try
            {
                doService(request,response);
            }
            catch(Exception e)
            {
                记录异常信息
            }
        }
    }
    // 注意访问权限定义成protected，显得既专业，又严谨，因为它是专门给子类用的
    protected abstract void doService(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException;
}

public class MyServlet1 extends BaseServlet
{
    protected void doService(HttpServletRequest request, HttpServletResponse response) throws IOException ,ServletException
    {
        本Servlet只处理的具体业务逻辑代码
    }
}