Jake Wharton之ViewPagerIndicator解读预备役

Posted 2022-12-10 王梵

关于自定义View的属性零碎知识

自定义View和自定义属性的知识不再此提及，这里着重说的是属性在自定义View中的获取方式，自定义的属性如下：

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="Wisely">
        <attr name="wisely_1" format="boolean" />
        <attr name="wisely_2" format="boolean" />
        <attr name="wisely_3" format="boolean" />
        <attr name="wisely_4" format="boolean" />
    </declare-styleable>
    
    <attr name="wisely_out" format="boolean" />

</resources>

自定义View的相关代码如下：

public CustomView(Context context, AttributeSet attrs) 
	super(context, attrs);
	TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.Wisely);
	typedArray.getBoolean(R.styleable.Wisely_wisely_1, true);
	typedArray.recycle();

重点看R.styleable.Wisely，它返回的是一个数组，而R.styleable.Wisely_wisely_1表示的则是数组的索引，它们在R文件中的表示如下：

public static final class attr 
	public static final int wisely_1 = 0x7f010000;

	public static final int wisely_2 = 0x7f010001;

	public static final int wisely_3 = 0x7f010002;

	public static final int wisely_4 = 0x7f010003;

	public static final int wisely_out = 0x7f010004;



public static final class styleable 
	public static final int[] Wisely =  0x7f010000, 0x7f010001,
			0x7f010002, 0x7f010003 ;

	public static final int Wisely_wisely_1 = 0;

	public static final int Wisely_wisely_2 = 1;

	public static final int Wisely_wisely_3 = 2;

	public static final int Wisely_wisely_4 = 3;

从上面可以看出一点，wisely_out也是attrs.xml中的属性，不过它是写在以Wisely命名的标签之外的，所以并未列入到styleable类的Wisely数组中。