自定义控件：流式布局

实现代码

public class FlowLayout extends ViewGroup {
private List<Line> mLines = new ArrayList<Line>(); // 用来记录描述有多少行View
private Line mCurrrenLine;                      // 用来记录当前已经添加到了哪一行
private int mHorizontalSpace = 10;
private int mVerticalSpace = 10;

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

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

public void setSpace(int horizontalSpace, int verticalSpace) {
this.mHorizontalSpace = horizontalSpace;
this.mVerticalSpace = verticalSpace;
    }

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// 清空
        mLines.clear();
        mCurrrenLine = null;

int layoutWidth = MeasureSpec.getSize(widthMeasureSpec);

// 获取行最大的宽度
int maxLineWidth = layoutWidth - getPaddingLeft() - getPaddingRight();

// 测量孩子
int count = getChildCount();
for (int i = 0; i < count; i++) {
            View view = getChildAt(i);

// 如果孩子不可见
if (view.getVisibility() == View.GONE) {
continue;
            }

// 测量孩子
            measureChild(view, widthMeasureSpec, heightMeasureSpec);

// 往lines添加孩子
if (mCurrrenLine == null) {
// 说明还没有开始添加孩子
                mCurrrenLine = new Line(maxLineWidth, mHorizontalSpace);

// 添加到 Lines中
                mLines.add(mCurrrenLine);

// 行中一个孩子都没有
                mCurrrenLine.addView(view);
            } else {
// 行不为空,行中有孩子了
boolean canAdd = mCurrrenLine.canAdd(view);
if (canAdd) {
// 可以添加
                    mCurrrenLine.addView(view);
                } else {
// 不可以添加,装不下去
// 换行

// 新建行
                    mCurrrenLine = new Line(maxLineWidth, mHorizontalSpace);
// 添加到lines中
                    mLines.add(mCurrrenLine);
// 将view添加到line
                    mCurrrenLine.addView(view);
                }
            }
        }

// 设置自己的宽度和高度
int measuredWidth = layoutWidth;
// paddingTop + paddingBottom + 所有的行间距 + 所有的行的高度

float allHeight = 0;
for (int i = 0; i < mLines.size(); i++) {
float mHeigth = mLines.get(i).mHeigth;

// 加行高
            allHeight += mHeigth;
// 加间距
if (i != 0) {
                allHeight += mVerticalSpace;
            }
        }

int measuredHeight = (int) (allHeight + getPaddingTop() + getPaddingBottom() + 0.5f);
        setMeasuredDimension(measuredWidth, measuredHeight);
    }

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// 给Child 布局---> 给Line布局

int paddingLeft = getPaddingLeft();
int offsetTop = getPaddingTop();
for (int i = 0; i < mLines.size(); i++) {
            Line line = mLines.get(i);

// 给行布局
            line.layout(paddingLeft, offsetTop);

            offsetTop += line.mHeigth + mVerticalSpace;
        }
    }

    class Line {
private List<View> mViews = new ArrayList<View>();    // 用来记录每一行有几个View
private float mMaxWidth;                            // 行最大的宽度
private float mUsedWidth;                        // 已经使用了多少宽度
private float mHeigth;                            // 行的高度
private float mMarginLeft;
private float mMarginRight;
private float mMarginTop;
private float mMarginBottom;
private float mHorizontalSpace;                    // View和view之间的水平间距

public Line(int maxWidth, int horizontalSpace) {
this.mMaxWidth = maxWidth;
this.mHorizontalSpace = horizontalSpace;
        }

/**
 * 添加view，记录属性的变化
 * @param view
 */
public void addView(View view) {
// 加载View的方法

int size = mViews.size();
int viewWidth = view.getMeasuredWidth();
int viewHeight = view.getMeasuredHeight();
// 计算宽和高
if (size == 0) {
// 说还没有添加View
if (viewWidth > mMaxWidth) {
                    mUsedWidth = mMaxWidth;
                } else {
                    mUsedWidth = viewWidth;
                }
                mHeigth = viewHeight;
            } else {
// 多个view的情况
                mUsedWidth += viewWidth + mHorizontalSpace;
                mHeigth = mHeigth < viewHeight ? viewHeight : mHeigth;
            }

// 将View记录到集合中
            mViews.add(view);
        }

/**
 * 用来判断是否可以将View添加到line中
 * @param view
 * @return
 */
public boolean canAdd(View view) {
// 判断是否能添加View
int size = mViews.size();
if (size == 0) {
return true;
            }

int viewWidth = view.getMeasuredWidth();

// 预计使用的宽度
float planWidth = mUsedWidth + mHorizontalSpace + viewWidth;

if (planWidth > mMaxWidth) {
// 加不进去
return false;
            }
return true;
        }

/**
 * 给孩子布局
 * @param offsetLeft
 * @param offsetTop
 */
public void layout(int offsetLeft, int offsetTop) {
// 给孩子布局

int currentLeft = offsetLeft;
int size = mViews.size();
// 判断已经使用的宽度是否小于最大的宽度
float extra = 0;
float widthAvg = 0;
if (mMaxWidth > mUsedWidth) {
                extra = mMaxWidth - mUsedWidth;
                widthAvg = extra / size;
            }

for (int i = 0; i < size; i++) {
                View view = mViews.get(i);
int viewWidth = view.getMeasuredWidth();
int viewHeight = view.getMeasuredHeight();

// 判断是否有富余
if (widthAvg != 0) {
// 改变宽度，View的长度改变了，需要重新measure
int newWidth = (int) (viewWidth + widthAvg + 0.5f);
int widthMeasureSpec = MeasureSpec.makeMeasureSpec(newWidth, MeasureSpec
                            .EXACTLY);
int heightMeasureSpec = MeasureSpec.makeMeasureSpec(viewHeight, MeasureSpec
                            .EXACTLY);
                    view.measure(widthMeasureSpec, heightMeasureSpec);
                    viewWidth = view.getMeasuredWidth();
                    viewHeight = view.getMeasuredHeight();
                }

// 布局
int left = currentLeft;
int top = (int) (offsetTop + (mHeigth - viewHeight) / 2 + 0.5f);
// int top = offsetTop;
int right = left + viewWidth;
int bottom = top + viewHeight;
                view.layout(left, top, right, bottom);
                currentLeft += viewWidth + mHorizontalSpace;
            }
        }
    }

}

public class FlowActivity extends AppCompatActivity {

private ScrollView mScrollView;
private FlowLayout mFlowLayout;
private List<String> mData;
private Gson mGson;
private String appname = "['QQ','视频','京东','youni有你','万年历-农历黄历','支付宝钱包']";

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
        initData();
        initView();
    }

private void initData() {
        mGson = new Gson();
        mData = mGson.fromJson(appname,new TypeToken<List<String>>(){}.getType());
    }

private void initView() {
        setContentView(mScrollView = new ScrollView(this));

        SpannableString title = new SpannableString("流式布局,热门标签");
        title.setSpan(new ForegroundColorSpan(Color.WHITE),0,title.length(),
                Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
        ActionBar actionBar = getSupportActionBar();
        actionBar.setTitle(title);

        mScrollView.setBackgroundColor(Color.parseColor("#eaeaea"));
        mScrollView.setVerticalScrollBarEnabled(false);
        mFlowLayout = new FlowLayout(this);

int padding = UIUtil.dip2px(15);
        mFlowLayout.setPadding(UIUtil.dip2px(10), padding, UIUtil.dip2px(10), padding);
        mFlowLayout.setSpace(UIUtil.dip2px(10), UIUtil.dip2px(15));
for (final String data : mData) {

            TextView textView = new TextView(this);
int tvPadding = UIUtil.dip2px(10);
            textView.setPadding(UIUtil.dip2px(15), tvPadding, UIUtil.dip2px(15), tvPadding);
            textView.setGravity(Gravity.CENTER);
            textView.setTextSize(16);
            textView.setText(data);
            textView.setTextColor(Color.WHITE);

            Random random = new Random();//Math.random()
int alpha = 255;
int green = random.nextInt(190) + 30;
int red = random.nextInt(190) + 30;
int blue = random.nextInt(190) + 30;
int argb = Color.argb(alpha, red, green, blue);

//设置shape
            GradientDrawable normalDrawable = new GradientDrawable();
            normalDrawable.setCornerRadius(UIUtil.dip2px(6));
            normalDrawable.setColor(argb);

            GradientDrawable pressedDrawable = new GradientDrawable();
            pressedDrawable.setColor(Color.DKGRAY);
            pressedDrawable.setCornerRadius(UIUtil.dip2px(5));


//设置选择器selector
            StateListDrawable stateListDrawable = new StateListDrawable();
            stateListDrawable.addState(new int[]{android.R.attr.state_pressed}, pressedDrawable);
            stateListDrawable.addState(new int[]{}, normalDrawable);

            textView.setBackgroundDrawable(stateListDrawable);
            textView.setClickable(true);
            textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
                    ToastUtil.toast(data);
                }
            });
            mFlowLayout.addView(textView);
        }

        mScrollView.addView(mFlowLayout);
    }
}