Java中运用的的设计模式 - 结构模式

Java中应用的的设计模式 - 结构模式

Structural patterns

Adapter?(recognizeable by creational methods taking an instance of?different?abstract/interface type and returning an implementation of own/another abstract/interface type which?decorates/overrides?the given instance)

• java.io.InputStreamReader(InputStream)?(returns a?Reader)
• java.io.OutputStreamWriter(OutputStream)?(returns a?Writer)
• javax.xml.bind.annotation.adapters.XmlAdapter#marshal()?and?#unmarshal()

  Bridge?(recognizeable by creational methods taking an instance of?different?abstract/interface type and returning an implementation of own abstract/interface type which?delegates/uses?the given instance)

  • None comes to mind yet. A fictive example would be?new LinkedHashMap(LinkedHashSet<K>, List<V>)?which returns an unmodifiable linked map which doesn't clone the items, but?uses?them. The?java.util.Collections#newSetFromMap()?and?singletonXXX()?methods however comes close.

    Composite?(recognizeable by behavioral methods taking an instance of?same?abstract/interface type)

    • java.util.Map#putAll(Map)
    • java.util.List#addAll(Collection)
    • java.util.Set#addAll(Collection)
    • java.nio.ByteBuffer#put(ByteBuffer)?(also on?CharBuffer,?ShortBuffer,?IntBuffer,LongBuffer,?FloatBuffer?and?DoubleBuffer)
    • java.awt.Container#add(Component)?(practically all over Swing thus)

      Decorator?(recognizeable by creational methods taking an instance of?same?abstract/interface type)

      • All subclasses of?java.io.InputStream,?OutputStream,?Reader?and?Writer?have a constructor taking an instance of same type.
      • Almost all implementations of?java.util.List,?Set?and?Map?have a constructor taking an instance of same type.
      • java.util.Collections, the?checkedXXX(),?synchronizedXXX()?and?unmodifiableXXX()methods.
      • javax.servlet.http.HttpServletRequestWrapper?and?HttpServletResponseWrapper

        Facade?(recognizeable by behavioral methods which internally uses instances of?different?independent abstract/interface types)

        • javax.faces.webapp.FacesServlet, it internally uses under each the abstract/interface typesServletContext,?LifeCycle,?ViewHandler,?NavigationHandler?and many more without that the enduser has to worry about it (which are however overrideable by injection).

          Flyweight?(recognizeable by creational methods returning a cached instance, a bit the "multiton" idea)

          • java.lang.Integer#valueOf(int)?(also on?Boolean,?Byte,?Character,?Short,?Long,?Floatand?Double)

            Proxy?(recognizeable by creational methods which returns an implementation of given abstract/interface type which in turn?delegates/uses?a?different?implementation of given abstract/interface type)

            • java.lang.reflect.Proxy
            • java.rmi.*, the whole API actually.

              ^{_{The Wikipedia example is IMHO a bit poor, lazy loading has actually completely nothing to do with the proxy pattern at all.}}