//抽象課程類
public abstract class Course
{
    protected final void makeCourse() {
        this.makePPT();
        this.makeVideo();
        if (needWriteArticle()) {
            this.writeArticle();
        }
        this.packageCourse();
    }
    //final表示子類繼承后，無(wú)法修改父類該方法
    final void makePPT() {
        System.out.println("1. 制作PPT");
    }
    final void makeVideo() {
        System.out.println("2. 制作視頻");
    }
    final void writeArticle() {
        System.out.println("3. 編寫課程筆記");
    }
    //鉤子方法
    protected boolean needWriteArticle() {
        return false;
    }
   //抽象方法，留給子類去實(shí)現(xiàn)
    abstract void packageCourse();
}

public class JavaCourse extends Course {
    @Override
    void packageCourse() {
        System.out.println("4. 提供Java課程源代碼");
    }
    @Override
    protected boolean needWriteArticle() {
        return true;
    }
}

public class JavaCourse extends Course {
    @Override
    void packageCourse() {
        System.out.println("4. 提供Java課程源代碼");
    }
    @Override
    protected boolean needWriteArticle() {
        return true;
    }
}

public class TEST
{
    public static void main(String[] args) {
                System.out.println("Java課程start---");
                Course javaCourse = new JavaCourse();
                javaCourse.makeCourse();
                System.out.println("Java課程end---\n");
                System.out.println("前端課程start---");
                Course feCourse = new FECourse(false);
                feCourse.makeCourse();
                System.out.println("前端課程end---");
    }
}

public abstract class HttpServlet extends GenericServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void doHead(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void doDelete(HttpServletRequest req,  HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void doTrace(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // ...
    }
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String method = req.getMethod();
        if (method.equals(METHOD_GET)) {
            long lastModified = getLastModified(req);
            if (lastModified == -1) {
                // servlet doesn't support if-modified-since, no reason
                // to go through further expensive logic
                doGet(req, resp);
            } else {
                long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
                if (ifModifiedSince < lastModified) {
                    // If the servlet mod time is later, call doGet()
                    // Round down to the nearest second for a proper compare
                    // A ifModifiedSince of -1 will always be less
                    maybeSetLastModified(resp, lastModified);
                    doGet(req, resp);
                } else {
                    resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                }
            }
        } else if (method.equals(METHOD_HEAD)) {
            long lastModified = getLastModified(req);
            maybeSetLastModified(resp, lastModified);
            doHead(req, resp);
        } else if (method.equals(METHOD_POST)) {
            doPost(req, resp);
        } else if (method.equals(METHOD_PUT)) {
            doPut(req, resp);
        } else if (method.equals(METHOD_DELETE)) {
            doDelete(req, resp);
        } else if (method.equals(METHOD_OPTIONS)) {
            doOptions(req,resp);
        } else if (method.equals(METHOD_TRACE)) {
            doTrace(req,resp);
        } else {
            //
            // Note that this means NO servlet supports whatever
            // method was requested, anywhere on this server.
            //
            String errMsg = lStrings.getString("http.method_not_implemented");
            Object[] errArgs = new Object[1];
            errArgs[0] = method;
            errMsg = MessageFormat.format(errMsg, errArgs);
            resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
        }
    }
    // ...省略...
}

// 擴(kuò)展 HttpServlet 類
public class HelloWorld extends HttpServlet {
  public void init() throws ServletException {
    // ...
  }
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      response.setContentType("text/html");
      PrintWriter out = response.getWriter();
      out.println("<h1>Hello World!</h1>");
  }
  public void destroy() {
      // ...
  }
}

public interface ConfigurableApplicationContext extends ApplicationContext, Lifecycle, Closeable {
　　/**聲明了一個(gè)模板方法*/
　　void refresh() throws BeansException, IllegalStateException;
}

public abstract class AbstractApplicationContext extends DefaultResourceLoader
        implements ConfigurableApplicationContext, DisposableBean {
　　 /**模板方法的具體實(shí)現(xiàn)*/
    public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            // Prepare this context for refreshing.
            prepareRefresh();
　　　　　　  //注意這個(gè)方法是，里面調(diào)用了兩個(gè)抽象方法refreshBeanFactory、getBeanFactory
            // Tell the subclass to refresh the internal bean factory.
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
            // Prepare the bean factory for use in this context.
            prepareBeanFactory(beanFactory);
            try {
　　　　　　　　　 //注意這個(gè)方法是鉤子方法
                // Allows post-processing of the bean factory in context subclasses.
                postProcessBeanFactory(beanFactory);
                // Invoke factory processors registered as beans in the context.
                invokeBeanFactoryPostProcessors(beanFactory);
                // Register bean processors that intercept bean creation.
                registerBeanPostProcessors(beanFactory);
                // Initialize message source for this context.
                initMessageSource();
                // Initialize event multicaster for this context.
                initApplicationEventMulticaster();
　　　　　　　　　 //注意這個(gè)方法是鉤子方法
                // Initialize other special beans in specific context subclasses.
                onRefresh();
                // Check for listener beans and register them.
                registerListeners();
                // Instantiate all remaining (non-lazy-init) singletons.
                finishBeanFactoryInitialization(beanFactory);
                // Last step: publish corresponding event.
                finishRefresh();
            }
            catch (BeansException ex) {
                // Destroy already created singletons to avoid dangling resources.
                destroyBeans();
                // Reset 'active' flag.
                cancelRefresh(ex);
                // Propagate exception to caller.
                throw ex;
            }
        }
    }

 protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
    }
    protected void onRefresh() throws BeansException {
        // For subclasses: do nothing by default.
    }

/**其實(shí)他內(nèi)部只調(diào)用了兩個(gè)抽象方法**/    
　　protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
        refreshBeanFactory();
        ConfigurableListableBeanFactory beanFactory = getBeanFactory();
        if (logger.isDebugEnabled()) {
            logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
        }
        return beanFactory;
    }
　　protected abstract void refreshBeanFactory() throws BeansException, IllegalStateException;
　　public abstract ConfigurableListableBeanFactory getBeanFactory() throws IllegalStateException;

public abstract class AbstractRefreshableApplicationContext extends AbstractApplicationContext {
    @Override
    public final ConfigurableListableBeanFactory getBeanFactory() {
        synchronized (this.beanFactoryMonitor) {
            if (this.beanFactory == null) {
                throw new IllegalStateException("BeanFactory not initialized or already closed - " +
                        "call 'refresh' before accessing beans via the ApplicationContext");
            }
            //這里的this.beanFactory在另一個(gè)抽象方法refreshBeanFactory的設(shè)置的
            return this.beanFactory;
        }
    }
}    
public class GenericApplicationContext extends AbstractApplicationContext implements BeanDefinitionRegistry {
    @Override
    public final ConfigurableListableBeanFactory getBeanFactory() {
　　　　//同樣這里的this.beanFactory在另一個(gè)抽象方法中設(shè)置        
　　　　return this.beanFactory;
    }
}