虽然网上一大堆这种流式布局，但是自己亲手写一遍，还是很有收获的。可以设置item间隙，还有setAdapter方法，用起来很方便。

效果图

device-111.png

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public class FlowLayout extends ViewGroup {
private int horizontalmargin = 10;
private int verticalmargin = 10;
private int childMaxHeight;

public FlowLayout(Context context) {
    this(context, null);
}

public FlowLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
}

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

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    int width = MeasureSpec.getSize(widthMeasureSpec);
    //item最大高度
    childMaxHeight = 0;
    //行数
    int lineCount = 1;

    int paddingLeft = getPaddingLeft();
    int paddingRight = getPaddingRight();
    int padding = paddingLeft + paddingRight;
    
    //当前行宽
    int columWidth = padding;

    int childCount = getChildCount();
    for (int i = 0; i < childCount; i++) {
        View child = getChildAt(i);
        
        //测量子view宽高，才能使用child.getMeasuredWidth();
        measureChild(child,widthMeasureSpec,heightMeasureSpec);

        int measuredWidth = child.getMeasuredWidth();
        int measuredHeight = child.getMeasuredHeight();

        if (measuredHeight > childMaxHeight) {
            childMaxHeight = measuredHeight;
        }

        columWidth = columWidth+measuredWidth + horizontalmargin;
        if (columWidth >= width) {
            lineCount++;
            columWidth = padding+measuredWidth + horizontalmargin;
        }
    }

    //flowlayout总高度
    int height = lineCount * childMaxHeight + (lineCount - 1) * verticalmargin+getPaddingTop()+getPaddingBottom();
    
    height = Math.max(height,0);
    setMeasuredDimension(width,height);
}


private static final String TAG = "FlowLayout";
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {

    int measuredWidth = getMeasuredWidth();


    int start = getPaddingLeft();
    int paddingRight = getPaddingRight();

    //第几行
    int lineIndex =0;
    //行宽
    int lineWidth =start;

    for (int i = 0; i < getChildCount(); i++) {

        View child = getChildAt(i);
        int childMeasuredWidth = child.getMeasuredWidth();
        int childMeasuredHeight = child.getMeasuredHeight();


        if(lineWidth+childMeasuredWidth>measuredWidth){//超出一行宽度换行
            lineIndex++;
            lineWidth=start;
        }

        int top = lineIndex*childMaxHeight+verticalmargin*lineIndex+(childMaxHeight-childMeasuredHeight)/2+getPaddingTop();
        int left = lineWidth;

        //摆放子view
        child.layout(left,top,left+childMeasuredWidth,top+childMeasuredHeight);

        lineWidth=lineWidth+childMeasuredWidth+horizontalmargin;

    }


}

public void setAdapter(BaseAdapter adapter){
    if(adapter==null){
        return;
    }
    removeAllViews();
    int count = adapter.getCount();
    if(count>0){
        for (int i = 0; i < count; i++) {
            View view = adapter.getView(i, null, null);
            addView(view);
        }
    }
}

}
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