设计模式与Android(篇一)

private Object readResolve() throws ObjectStreamException(){    return sInstent;        // 返回单例中的实例对象}

class ContextImpl extends Context {    // 存储所有系统服务的集合    private static final HashMap<String, ServiceFetcher> SYSTEM_SERVICE_MAP =new HashMap<String, ServiceFetcher>();        // 一个注册服务的并添加到结合的方法    private static void registerService(String serviceName, ServiceFetcher fetcher) {       if (!(fetcher instanceof StaticServiceFetcher)) {           fetcher.mContextCacheIndex = sNextPerContextServiceCacheIndex++;       }       SYSTEM_SERVICE_MAP.put(serviceName, fetcher);    }        // 静态语句块, 只在类第一次被加载的时候调用, 保证了服务只被添加一次.    static {        // 注册了LayoutInflate服务        registerService(LAYOUT_INFLATER_SERVICE, new ServiceFetcher() {                public Object createService(ContextImpl ctx) {                    return PolicyManager.makeNewLayoutInflater(ctx.getOuterContext());                }});                        registerService(INPUT_SERVICE, new StaticServiceFetcher() {                public Object createStaticService() {                    return InputManager.getInstance();                }});        /**         *  后面省略一大坨的注册的服务代码        **/    }    }

// 一个粗略的创建dialog// 创建构建者builder角色AlertDialog.Builder builder = new AlertDialog.Builder(this);builder.setIcon(android.R.drawable.sym_def_app_icon)      .setTitle("标题")      .setMessage("message")      // 设置点击等..      .setPositiveButton("确定", null);// 构建AlertDialog alertDialog = builder.create();// 显示alertDialog.show();

public class AlertDialog extends Dialog implements DialogInterface {    // AlertController 这个对象会保存Builder对象中的各个参数    private AlertController mAlert;        // 实际上操作的是上面这个变量中的属性    @Override    public void setTitle(CharSequence title) {        super.setTitle(title);        mAlert.setTitle(title);    }        public void setMessage(CharSequence message) {        mAlert.setMessage(message);    }    // 省略一坨代码如各种setter等    // Builder以内部类的形式存在    public static class Builder {        // 1.存储AlertDialog的各个参数 如title,icon等        private final AlertController.AlertParams P;                // 构造函数        public Builder(Context context) {            this(context, resolveDialogTheme(context, 0));        }        // 2. 设置参数, 我们构建的Builder设置的参数就是这些方法        public Builder setTitle(int titleId) {            P.mTitle = P.mContext.getText(titleId);            return this;        }                public Builder setTitle(CharSequence title) {            P.mTitle = title;            return this;        }                // ....                // 3.构建AlertDialog, 传递参数        public AlertDialog create() {            // 4.因为已经通过builder设置了参数, 接下来就可以创建真正需要的AlertDialog对象            final AlertDialog dialog = new AlertDialog(P.mContext, mTheme, false);                        // 5.将Builder类中的成员变量P应用到AlertDialog类中            P.apply(dialog.mAlert);            dialog.setCancelable(P.mCancelable);            if (P.mCancelable) {                dialog.setCanceledOnTouchOutside(true);            }            dialog.setOnCancelListener(P.mOnCancelListener);            dialog.setOnDismissListener(P.mOnDismissListener);            if (P.mOnKeyListener != null) {                dialog.setOnKeyListener(P.mOnKeyListener);            }            return dialog;        }          }   }

// AlertDialog类protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   mAlert.installContent();}// AlertController类public void installContent() {   // 设置窗口, 没有title类型   mWindow.requestFeature(Window.FEATURE_NO_TITLE);   int contentView = selectContentView();   // 设置窗口的内容视图   mWindow.setContentView(contentView);   // 初始化AlertDialog其他子视图的内容   setupView();   setupDecor();}

public class WordDocument implements Cloneable{    // 文本    public String mText;    // 图片名列表    public ArrayList<String> mImages = new ArrayList<String>();    public WordDocument(){        System.out.println("-----------WordDocument构造函数-----------");    }    @Override    protected WordDocument clone() {        try {            // 通过本地方法特殊途径, 构建一个对象            WordDocument doc = (WordDocument) super.clone();            doc.mText = this.mText;            // 因为Image是引用类型, 这样直接赋值属于浅拷贝, 再次对集合进行clone. 实现wordDocument的深拷贝            doc.mImages = (ArrayList<String>) this.mImages.clone();            return doc;        }catch (Exception ex){}        return null;    }    /**     * 打印文档内容     */    public void showDocument(){        System.out.println("------------开始输出内容---------------------");        System.out.println("Text: "+mText);        System.out.println("List: "+mImages.toString());        System.out.println("------------输出结束------------------------");    }}

@Overrideprotected WordDocument clone() {   try {       // 通过本地方法特殊途径, 构建一个对象       WordDocument doc = (WordDocument) super.clone();       doc.mText = this.mText;       // 这里进行修改 那么此时属于浅拷贝       doc.mImages = this.mImages;       return doc;}

public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, java.io.Serializable{    transient Object[] elementData;     private int size;        public Object clone() {        try {            ArrayList<?> v = (ArrayList<?>) super.clone();            v.elementData = Arrays.copyOf(elementData, size);            v.modCount = 0;            return v;        } catch (CloneNotSupportedException e) {            throw new InternalError(e);        }    }

Intent intent = new Intent("某一个activity的action");intent.putExtra("result", "Successful");// 调用克隆方法Intent clone = (Intent) intent.clone();startActivity(clone);

@Overridepublic Object clone() {   return new Intent(this);}/*** Copy constructor.*/public Intent(Intent o) {   this.mAction = o.mAction;   this.mData = o.mData;   this.mType = o.mType;   this.mPackage = o.mPackage;   this.mComponent = o.mComponent;   this.mFlags = o.mFlags;   this.mContentUserHint = o.mContentUserHint;   if (o.mCategories != null) {       this.mCategories = new ArraySet<String>(o.mCategories);   }   if (o.mExtras != null) {       this.mExtras = new Bundle(o.mExtras);   }   if (o.mSourceBounds != null) {       this.mSourceBounds = new Rect(o.mSourceBounds);   }   if (o.mSelector != null) {       this.mSelector = new Intent(o.mSelector);   }   if (o.mClipData != null) {       this.mClipData = new ClipData(o.mClipData);   }}

public interface Collection<E> extends Iterable<E> {    // ....}public interface Iterable<T> {    Iterator<T> iterator();        // 可能JDK1.8之后添加两个默认方法, 这里我们不需要关心}

public class ArrayList<E> extends AbstractList<E> implements Cloneable, Serializable, RandomAccess {@Override public Iterator<E> iterator() {        return new ArrayListIterator();    }    private class ArrayListIterator implements Iterator<E> {        private int remaining = size;                private int removalIndex = -1;        private int expectedModCount = modCount;        public boolean hasNext() {            return remaining != 0;        }        @SuppressWarnings("unchecked") public E next() {            ArrayList<E> ourList = ArrayList.this;            // 返回集合大小元素, 还有几个未遍历            int rem = remaining;            if (ourList.modCount != expectedModCount) {                throw new ConcurrentModificationException();            }            if (rem == 0) {                throw new NoSuchElementException();            }            remaining = rem - 1;            return (E) ourList.array[removalIndex = ourList.size - rem];        }        public void remove() {            Object[] a = array;            int removalIdx = removalIndex;            if (modCount != expectedModCount) {                throw new ConcurrentModificationException();            }            if (removalIdx < 0) {                throw new IllegalStateException();            }            System.arraycopy(a, removalIdx + 1, a, removalIdx, remaining);            a[--size] = null;  // Prevent memory leak            removalIndex = -1;            expectedModCount = ++modCount;        }    }}

// hashSet 复写逻辑public class HashSet<E> extends AbstractSet<E> implements Set<E>, Cloneable,Serializable {    public Iterator<E> iterator() {        return backingMap.keySet().iterator();    }}

// HashMap 复写逻辑public class HashMap<K, V> extends AbstractMap<K, V> implements Cloneable, Serializable {    Iterator<K> newKeyIterator() { return new KeyIterator();   }        private final class KeyIterator extends HashIterator            implements Iterator<K> {        public K next() { return nextEntry().key; }    }}

public class MainActivity extends Activity {    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(new FrameLayout(this));       }}

public static void main (String arg[]){   // 创建操作策略的环境类   TranficCalculator calculator = new TranficCalculator();   // 设置公交车的策略, 并准备计算   calculator.setStrategy(new BusStrategy());   System.out.println("公交车-->计算9公里价格: "+calculator.calculatePrice(9));   // 设置地铁的策略, 并准备计算   calculator.setStrategy(new SubwayStrategy());   System.out.println("地铁-->计算9公里价格: "+calculator.calculatePrice(9));}// 结果-->公交车-->计算9公里价格: 1地铁-->计算9公里价格: 4

public void startAnimation(Animation animation) {    // 1.初始化动画的开始时间   animation.setStartTime(Animation.START_ON_FIRST_FRAME);   // 2.对View设置动画   setAnimation(animation);   // 3.刷新父类缓存   invalidateParentCaches();   // 4.刷新View本身及子View   invalidate(true);}

protected boolean drawChild(Canvas canvas, View child, long drawingTime) {   // 简单的转发   return child.draw(canvas, this, drawingTime);}boolean draw(Canvas canvas, ViewGroup parent, long drawingTime) {    // ....    // 查看是否需要清除动画信息    final int flags = parent.mGroupFlags;    // 省略无关代码        // 获取设置的动画信息    final Animation a = getAnimation();            if (a != null) {            // 绘制动画           more = drawAnimation(parent, drawingTime, a, scalingRequired);           //...       } }

private boolean drawAnimation(ViewGroup parent, long drawingTime,       Animation a, boolean scalingRequired) {   Transformation invalidationTransform;   final int flags = parent.mGroupFlags;   final boolean initialized = a.isInitialized();   // 1. 判断动画是否已经初始化过   if (!initialized) {       a.initialize(mRight - mLeft, mBottom - mTop, parent.getWidth(), parent.getHeight());       a.initializeInvalidateRegion(0, 0, mRight - mLeft, mBottom - mTop);       if (mAttachInfo != null) a.setListenerHandler(mAttachInfo.mHandler);       // 如果设置了动画的监听, 则触发对应的回调       onAnimationStart();   }   // 获取Transformation对象, 存储动画的信息   final Transformation t = parent.getChildTransformation();   // 2. 调用Animation#getTransformation, 通过计算获取动画的相关值   boolean more = a.getTransformation(drawingTime, t, 1f);       if (more) {        // 3. 根据具体实现, 判断当前动画类型是否需要进行调整位置大小, 然后刷新不同的区域       if (!a.willChangeBounds()) {           // ...       } else {           // 获取重绘区域           a.getInvalidateRegion(0, 0, mRight - mLeft, mBottom - mTop, region,                   invalidationTransform);           parent.mPrivateFlags |= PFLAG_DRAW_ANIMATION;            // 更新计算有效区域           final int left = mLeft + (int) region.left;           final int top = mTop + (int) region.top;                      // 进行区域更新           parent.invalidate(left, top, left + (int) (region.width() + .5f),                   top + (int) (region.height() + .5f));       }   }   return more;}

public boolean getTransformation(long currentTime, Transformation outTransformation) {   //...   float normalizedTime;   // 1.计算当前时间的流逝百分比   if (duration != 0) {       normalizedTime = ((float) (currentTime - (mStartTime + startOffset))) /               (float) duration;   } else {       // time is a step-change with a zero duration       normalizedTime = currentTime < mStartTime ? 0.0f : 1.0f;   }   // 动画是否完成标记   final boolean expired = normalizedTime >= 1.0f;   mMore = !expired;   if ((normalizedTime >= 0.0f || mFillBefore) && (normalizedTime <= 1.0f || mFillAfter)) {        // 2.通过插值器获取动画执行百分比  , 这里获取的方法就是通过策略模式       final float interpolatedTime = mInterpolator.getInterpolation(normalizedTime);       // 3.应用动画效果       applyTransformation(interpolatedTime, outTransformation);   }   // 4. 如果动画执行完毕, 那么触发动画完成的回调或者执行重复动画等操作   // ...   if (!mMore && mOneMoreTime) {       mOneMoreTime = false;       return true;   }   return mMore;}