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简介：在系统中要创建大量的对象，这些对象之间具有几乎完全相同的功能，只是在细节上有一点儿差别
用原型实例指定创建对象的种类，并且通过拷贝这些原型创建新的对象
example 1：
我们需要一张Bitmap的几种不同格式：ARGB_8888、RGB_565、ARGB_4444、ALAPHA_8等。那我们就可以先创建一个ARGB_8888的Bitmap作为原型，在它的基础上，通过调用Bitmap.copy(Config)来创建出其它几种格式的Bitmap
/** * Tries to make a new bitmap based on the dimensions of this bitmap, * setting the new bitmap‘s config to the one specified, and then copying * this bitmap‘s pixels into the new bitmap. If the conversion is not * supported, or the allocator fails, then this returns NULL. The returned * bitmap initially has the same density as the original. * * @param config The desired config for the resulting bitmap * @param isMutable True if the resulting bitmap should be mutable (i.e. * its pixels can be modified) * @return the new bitmap, or null if the copy could not be made. */ public Bitmap copy(Config config, boolean isMutable) { checkRecycled("Can‘t copy a recycled bitmap"); Bitmap b = nativeCopy(mNativeBitmap, config.nativeInt, isMutable); if (b != null) { b.setPremultiplied(mRequestPremultiplied); b.mDensity = mDensity; } return b; }
另外一个例子就是Java中所有对象都有的一个名字叫clone的方法
/** * 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); } } @Override public Object clone() { return new Intent(this); }
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原文地址：http://www.cnblogs.com/suncan/p/4331859.html
