public abstract GenericServlet implements Servlet{
  @Override
  public void init(ServletConfig servletConfig) throws ServletException {
    }
  @Override
  public ServletConfig getServletConfig() {
        return null;
    }
  public abstract void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException;
  @Override
  public String getServletInfo() {
        return null;
    }
   @Override
  public void destroy() {
    }
}

public class targetClass extende GenericServlet(){
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException{
    System.out.println("Target's service is executing");
    }
}

public abstract GenericServlet implements Servlet{
	//config對象可能在其他方法中會被使用到，因此需要定義一個(gè)成員變量
	private ServletConfig config;
  @Override
  //不能讓子類重寫init方法，因?yàn)榧尤隿onfig=null,會出問題，所以要給init方法加關(guān)鍵字final來阻止init方法被重寫
  public final void init(ServletConfig config) throws ServletException {
			this.config=config;
			//如果必須在子類重寫init方法，可以重載以后一個(gè)init方法，在原來的init方法中調(diào)用即可
			this.init();
    }
	public void init(){
	}
  @Override
  public ServletConfig getServletConfig() {
        return config;
    }
  public abstract void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException;
  @Override
  public String getServletInfo() {
        return null;
    }
   @Override
  public void destroy() {
    }
}