351_setFactory解析

setFactory解析


阅读鸿洋大神博客笔记


博客地址:http://blog.csdn.net/lmj623565791/article/details/51503977






先看看Inflator的setFactory和setFactory2


        new LayoutInflater().setFactory();
        new LayoutInflater().setFactory2();


    /**
     * Attach a custom Factory interface for creating views while using
     * this LayoutInflater.  This must not be null, and can only be set once;
     * after setting, you can not change the factory.  This is
     * called on each element name as the xml is parsed. If the factory returns
     * a View, that is added to the hierarchy. If it returns null, the next
     * factory default {@link #onCreateView} method is called.
     * 
     * <p>If you have an existing
     * LayoutInflater and want to add your own factory to it, use
     * {@link #cloneInContext} to clone the existing instance and then you
     * can use this function (once) on the returned new instance.  This will
     * merge your own factory with whatever factory the original instance is
     * using.
     */
    public void setFactory(Factory factory) {
        if (mFactorySet) {
            throw new IllegalStateException("A factory has already been set on this LayoutInflater");
        }
        if (factory == null) {
            throw new NullPointerException("Given factory can not be null");
        }
        mFactorySet = true;
        if (mFactory == null) {
            mFactory = factory;
        } else {
            mFactory = new FactoryMerger(factory, null, mFactory, mFactory2);
        }
    }




    /**
     * Like {@link #setFactory}, but allows you to set a {@link Factory2}
     * interface.
     */
    public void setFactory2(Factory2 factory) {
        if (mFactorySet) {
            throw new IllegalStateException("A factory has already been set on this LayoutInflater");
        }
        if (factory == null) {
            throw new NullPointerException("Given factory can not be null");
        }
        mFactorySet = true;
        if (mFactory == null) {
            mFactory = mFactory2 = factory;
        } else {
            mFactory = mFactory2 = new FactoryMerger(factory, factory, mFactory, mFactory2);
        }
    }






居然几乎一模一样
setFactory2是在SDK>=11以后引入的




有一个类直接就实现了兼容
LayoutInflatorCompat,也是setFactory方法,来看看


    /**
     * Attach a custom Factory interface for creating views while using
     * this LayoutInflater. This must not be null, and can only be set once;
     * after setting, you can not change the factory.
     *
     * @see LayoutInflater#setFactory(android.view.LayoutInflater.Factory)
     */
    public static void setFactory(LayoutInflater inflater, LayoutInflaterFactory factory) {
        IMPL.setFactory(inflater, factory);
    }




来用一下


参数是LayoutInflater inflater, LayoutInflaterFactory factory


        LayoutInflaterCompat.setFactory(LayoutInflater.from(this), new LayoutInflaterFactory() {
            @Override
            public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
                Log.e(TAG, "name = " + name);
                int n = attrs.getAttributeCount();
                for (int i = 0; i < n; i++)
                {
                    Log.e(TAG, attrs.getAttributeName(i) + " , " + attrs.getAttributeValue(i));
                }
                return null;
            }
        });


我们打印一下name,再打印一下attrs里面获取的attributeName


注意        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
要放在下面,不然会报错




打印结果是:
MainActivity﹕ name = TextView
MainActivity﹕ layout_width , -2
MainActivity﹕ layout_height , -2
MainActivity﹕ text , @2131099670


我们试试把TextView换成Button


if (name.equals("TextView"))
{
    Button button = new Button(context, attrs);
    return button;
}