Java中的适配器原理解析

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对象可能在其他方法中会被使用到，因此需要定义一个成员变量
	private ServletConfig config;
  @Override
  //不能让子类重写init方法，因为加入config=null,会出问题，所以要给init方法加关键字final来阻止init方法被重写
  public final void init(ServletConfig config) throws ServletException {
			this.config=config;
			//如果必须在子类重写init方法，可以重载以后一个init方法，在原来的init方法中调用即可
			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() {
    }
}