RecyclerView实现设置最大高度maxHeight

RecyclerView是没有maxHeight属性配置的，但我们可以通过继承RecyclerView自定义实现此属性功能。

具体实现如下：

public class MaxHeightRecyclerView extends RecyclerView {
    private int mMaxHeight;

    public MaxHeightRecyclerView(Context context) {
        super(context);
    }

    public MaxHeightRecyclerView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initialize(context, attrs);
    }

    public MaxHeightRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initialize(context, attrs);
    }

    private void initialize(Context context, AttributeSet attrs) {
        TypedArray arr = context.obtainStyledAttributes(attrs, R.styleable.MaxHeightRecyclerView);
        mMaxHeight = arr.getLayoutDimension(R.styleable.MaxHeightRecyclerView_maxHeight, mMaxHeight);
        arr.recycle();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (mMaxHeight > 0) {
            heightMeasureSpec = MeasureSpec.makeMeasureSpec(mMaxHeight, MeasureSpec.AT_MOST);
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

在style.xml文件中加入：

<declare-styleable name="MaxHeightRecyclerView">
    <attr name="maxHeight" format="dimension" />
</declare-styleable>

然后就可以在xml中使用：

app:maxHeight="400dp"