1、高仿小米商城項目，愛了！
2、為什么有些公司不讓用 Lombok ？
3、厲害了，為了干掉 HTTP ，Spring 團隊開源了 nohttp 項目！
4、別瞎學(xué)了，這幾門語言要被淘汰了！
5、一個基于 Spring Boot 的項目骨架，非常舒服！

public Object getSingleton(String beanName){
    //參數(shù)true設(shè)置標(biāo)識允許早期依賴
    return getSingleton(beanName,true);
}
protected Object getSingleton(String beanName, boolean allowEarlyReference) {
    //檢查緩存中是否存在實例
    Object singletonObject = this.singletonObjects.get(beanName);
    if (singletonObject == null && isSingletonCurrentlyInCreation(beanName)) {
        //如果為空，則鎖定全局變量并進行處理。
        synchronized (this.singletonObjects) {
            //如果此bean正在加載，則不處理
            singletonObject = this.earlySingletonObjects.get(beanName);
            if (singletonObject == null && allowEarlyReference) {
                //當(dāng)某些方法需要提前初始化的時候則會調(diào)用addSingleFactory 方法將對應(yīng)的ObjectFactory初始化策略存儲在singletonFactories
                ObjectFactory<?> singletonFactory = this.singletonFactories.get(beanName);
                if (singletonFactory != null) {
                    //調(diào)用預(yù)先設(shè)定的getObject方法
                    singletonObject = singletonFactory.getObject();
                    //記錄在緩存中，earlysingletonObjects和singletonFactories互斥
                    this.earlySingletonObjects.put(beanName, singletonObject);
                    this.singletonFactories.remove(beanName);
                }
            }
        }
    }
    return (singletonObject != NULL_OBJECT ? singletonObject : null);
}

public abstract class ApplicationEvent extends EventObject {
    private static final long serialVersionUID = 7099057708183571937L;
    private final long timestamp;
    public ApplicationEvent(Object source) {
    super(source);
    this.timestamp = System.currentTimeMillis();
    }
    public final long getTimestamp() {
        return this.timestamp;
    }
}

public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {
     void onApplicationEvent(E event);
}

public interface ApplicationEventPublisher {
        void publishEvent(ApplicationEvent event);
}

public void publishEvent(ApplicationEvent event) {
    Assert.notNull(event, "Event must not be null");
    if (logger.isTraceEnabled()) {
         logger.trace("Publishing event in " + getDisplayName() + ": " + event);
    }
    getApplicationEventMulticaster().multicastEvent(event);
    if (this.parent != null) {
    this.parent.publishEvent(event);
    }
}

public abstract class AbstractApplicationContext extends DefaultResourceLoader
    implements ConfigurableApplicationContext, DisposableBean {
    private ApplicationEventMulticaster applicationEventMulticaster;
    protected void registerListeners() {
    // Register statically specified listeners first.
    for (ApplicationListener<?> listener : getApplicationListeners()) {
    getApplicationEventMulticaster().addApplicationListener(listener);
    }
    // Do not initialize FactoryBeans here: We need to leave all regular beans
    // uninitialized to let post-processors apply to them!
    String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
    for (String lisName : listenerBeanNames) {
    getApplicationEventMulticaster().addApplicationListenerBean(lisName);
    }
  }
}

public abstract class JdbcTemplate {
     public final Object execute（String sql）{
        Connection con=null;
        Statement stmt=null;
        try{
            con=getConnection（）;
            stmt=con.createStatement（）;
            Object retValue=executeWithStatement（stmt,sql）;
            return retValue;
        }catch（SQLException e）{
             ...
        }finally{
            closeStatement（stmt）;
            releaseConnection（con）;
        }
    }
    protected abstract Object executeWithStatement（Statement stmt, String sql）;
}

public interface StatementCallback{
    Object doWithStatement（Statement stmt）;
}

public class JdbcTemplate {
    public final Object execute（StatementCallback callback）{
        Connection con=null;
        Statement stmt=null;
        try{
            con=getConnection（）;
            stmt=con.createStatement（）;
            Object retValue=callback.doWithStatement（stmt）;
            return retValue;
        }catch（SQLException e）{
            ...
        }finally{
            closeStatement（stmt）;
            releaseConnection（con）;
        }
    }

    ...//其它方法定義
}

JdbcTemplate jdbcTemplate=...;
    final String sql=...;
    StatementCallback callback=new StatementCallback(){
    public Object=doWithStatement(Statement stmt){
        return ...;
    }
}
jdbcTemplate.execute(callback);