這裡所說的FlowLayout元件是來自鴻洋提供的一個流式佈局的框架
框架原始碼看這裡
框架作者部落格介紹看這裡

廢話不多說,直接上程式碼,主要就是修改FlowLayout的onMeasure和onLayout方法,同時我這裡還對onLayout方法優化了一下,減少了一次for迴圈處理行view,行高,行寬等資訊

public class FlowLayout extends ViewGroup {
    private static final String TAG = "FlowLayout";
    protected static final int LEFT =
 
 -1;
    protected static final int CENTER = 0;
    protected static final int RIGHT = 1;

    protected List<List<View>> mAllViews = new ArrayList<List<View>>();//記錄所有行
    protected List<Integer> mLineHeight = new ArrayList<Integer>();//記錄所有行高
    protected List<Integer>
 
 mLineWidth = new ArrayList<Integer>();//記錄所有行寬
    protected List<View> lineViews = new ArrayList<>();//臨時記錄每行的view
    protected int mGravity;
    private int maxLine = -1;//最大行數

    public void setMaxLine(int maxLine) {
        this.maxLine = maxLine;
    }

    public FlowLayout(Context context,
 
 AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.TagFlowLayout);
        mGravity = ta.getInt(R.styleable.TagFlowLayout_tag_gravity, LEFT);
        int layoutDirection = TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault());
        if (layoutDirection == LayoutDirection.RTL) {
            if (mGravity == LEFT) {
                mGravity = RIGHT;
            } else {
                mGravity = LEFT;
            }
        }
        ta.recycle();
    }

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

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


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

        mAllViews.clear();//記錄所有行的view
        mLineHeight.clear();//記錄每一行的高度
        mLineWidth.clear();//記錄每一行的寬度
        lineViews.clear();//記錄每一行的view

        int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
        int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
        int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
        int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

        // wrap_content 最終寬高
        int width = 0;
        int height = 0;

        //當前已用行寬高
        int lineWidth = 0;
        int lineHeight = 0;

        int cCount = getChildCount();

        for (int i = 0; i < cCount; i++) {
            View child = getChildAt(i);

            if (child.getVisibility() == View.GONE) {
                continue;
            }
            //測量子view
            measureChild(child, widthMeasureSpec, heightMeasureSpec);
            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
            //子View寬高
            int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
            int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;

            if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
                if (maxLine > 0 && mAllViews.size() + 1 >= maxLine) { //+1是因為後面還有最後一行
                    break;//超過最大行數跳出迴圈
                }
                //需要換行
                width = Math.max(width, lineWidth);//記錄最大行寬
                height += lineHeight;//累加包裹內容所需的高度

                //換行,儲存上一行資料
                mLineHeight.add(lineHeight);
                mLineWidth.add(lineWidth);
                mAllViews.add(lineViews);

				//重置新行變數
                lineWidth = 0;//重新賦值行寬
                lineHeight = 0;//重新賦值行高
                lineViews = new ArrayList<View>();
            }
			//記錄當前行資料
            lineWidth += childWidth;//累加行寬
            lineHeight = Math.max(lineHeight, childHeight);//取當前行最大高度作為行高
            lineViews.add(child);


        }

        //新增最後一行資料
        //包裹內容所需的最大寬度
        width = Math.max(lineWidth, width);
        height += lineHeight;
        mLineHeight.add(lineHeight);
        mLineWidth.add(lineWidth);
        mAllViews.add(lineViews);

        setMeasuredDimension(
                //父控制元件寬高確定則用確定的,否則用測量後的
                modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width + getPaddingLeft() + getPaddingRight(),
                modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height + getPaddingTop() + getPaddingBottom()//
        );

    }


    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        //總寬
        int width = getWidth();
        //當前已用行寬高
        int lineHeight = 0;
        //下面是對每一行的View進行佈局
        int left = getPaddingLeft();
        int top = getPaddingTop();
        int lineNum = mAllViews.size();
        for (int i = 0; i < lineNum; i++) {
            //獲取當前行和行高
            lineViews = mAllViews.get(i);
            lineHeight = mLineHeight.get(i);

            // set gravity
            int currentLineWidth = this.mLineWidth.get(i);
            switch (this.mGravity) {
                case LEFT:
                    left = getPaddingLeft();
                    break;
                case CENTER:
                    left = (width - currentLineWidth) / 2 + getPaddingLeft();
                    break;
                case RIGHT:
                    //  適配了rtl，需要補償一個padding值 ,從右邊向左開始佈局
                    left = width - (currentLineWidth + getPaddingLeft()) - getPaddingRight();
                    //  適配了rtl，需要把lineViews裡面的陣列倒序排,從右邊開始存放view
                    Collections.reverse(lineViews);
                    break;
            }
            //開始一行行地佈局子view
            for (int j = 0; j < lineViews.size(); j++) {
                View child = lineViews.get(j);
                if (child.getVisibility() == View.GONE) {
                    continue;
                }

                MarginLayoutParams lp = (MarginLayoutParams) child
                        .getLayoutParams();

                int lc = left + lp.leftMargin;
                int tc = top + lp.topMargin;
                int rc = lc + child.getMeasuredWidth();
                int bc = tc + child.getMeasuredHeight();

                child.layout(lc, tc, rc, bc);

                //更新下一個view新增到當前行的left
                left += child.getMeasuredWidth() + lp.leftMargin
                        + lp.rightMargin;
            }
            //更新下一個view新增到下一行的top
            top += lineHeight;
        }

    }

    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new MarginLayoutParams(getContext(), attrs);
    }

    @Override
    protected LayoutParams generateDefaultLayoutParams() {
        return new MarginLayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
    }

    @Override
    protected LayoutParams generateLayoutParams(LayoutParams p) {
        return new MarginLayoutParams(p);
    }

    /**
     * 獲取指定行數內的item個數
     *
     * @return 每行的個數之和
     * @lineNum 總行數
     */
    public int getTotalByLine(int lineNum) {
        int count = 0;
        if (lineNum <= mAllViews.size()) {
            for (int i = 0; i < lineNum; i++) {
                List<View> line = mAllViews.get(i);
                count += line.size();
            }
        }

        return count;
    }
}