Android自定义ViewGroup实现流式布局

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  allLines.clear();
  //测量容器的宽和高
  int containerMeasuredWidth = MeasureSpec.getSize(widthMeasureSpec);
  //这个集合用于保存单行
  ArrayList<View> oneLine = null;
  for (int i = 0; i < getChildCount(); i++) {
   //获取每一Chiledview
   View child = getChildAt(i);
    int UnspecifiedMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
   child.measure(UnspecifiedMeasureSpec, UnspecifiedMeasureSpec);//相当于传了一个0,0;
   //如果是第1个view就new一个新行出来,或者View大于了可用的宽度,
   if (i == 0 || child.getMeasuredWidth() > getUsablewWidth(containerMeasuredWidth, oneLine,oneLine.size())) {
    oneLine = new ArrayList<View>();
    allLines.add(oneLine);
   }
   oneLine.add(child);
 
  }
 
  int lineNumber = allLines.size();
  int allLinesHeight = getChildAt(0).getMeasuredHeight() * lineNumber;
  int verticalTotalpadding = getPaddingBottom() + getPaddingTop();
  //垂直总的spcing
  int verticalTotalSpcing = 8 * (lineNumber - 1);
  //容器的高 = 所有View的高 + 垂直方向的Padding + 垂直总的spcing
  int containerMeasureHeight = allLinesHeight + verticalTotalpadding + verticalTotalSpcing;
  setMeasuredDimension(containerMeasuredWidth, containerMeasureHeight);
 }

private int getUsablewWidth(int containerMeasuredWidth, ArrayList<View> oneLine,int needSpacingCount) {
  int oneLineWidth = 0;
  for (View view : oneLine) {
   oneLineWidth += view.getMeasuredWidth();
  }
  //水平方向两边的padding
  int horizotalPadding = getPaddingLeft() + getPaddingRight();
  int horizontalTotalSpcing = horizotalPadding * needSpacingCount;
  int usablewWidth = containerMeasuredWidth - oneLineWidth - horizotalPadding - horizontalTotalSpcing;
  return usablewWidth;
 }

protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int tempRight = 0;//保存一行中上一个View的Right
  int tempBottom = 0;//保存上一行View的Bottom位置
  ///遍历第一排
  for (int row = 0; row < allLines.size(); row++) {
   ArrayList<View> oneLines = allLines.get(row);
   //计算一行中每个Veiw可以分到的平均宽度
   int totalUsableWidth= getUsablewWidth(getMeasuredWidth(), oneLines,oneLines.size()-1);
   int averageUsablewWidth = totalUsableWidth/oneLines.size();
   //遍历的是一行的内容
   for (int column = 0; column < oneLines.size(); column++) {
    View child = oneLines.get(column);
    //获取测量的宽高
    int measuredWidth = child.getMeasuredWidth();
    int measuredHeight = child.getMeasuredHeight();
    //如果是一行中的第一个View则排在第0个位置
    int left = column == 0 ? getPaddingLeft() : tempRight + 8;
    //如果是第1行Top坐标是PaddingTop的位置,否则就上一个View的bottom位置
    int top = row == 0 ? getPaddingTop() : tempBottom + 8;
    int right = left + measuredWidth ;//+ averageUsablewWidth;
    
    int bootom = top + measuredHeight;
    child.layout(left, top, right, bootom);
    tempRight = right;
    
    int WidthMeasureSpec = MeasureSpec.makeMeasureSpec(child.getWidth(), MeasureSpec.EXACTLY);
    int HeightMakeMeasureSpec = MeasureSpec.makeMeasureSpec(child.getHeight(), MeasureSpec.EXACTLY);
    child.measure(WidthMeasureSpec,HeightMakeMeasureSpec);
   }
   tempBottom = oneLines.get(0).getBottom();
  }
 }

public class MainActivity extends Activity {
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 FlowLayout flowLayout = new FlowLayout(this);
 flowLayout.setPadding(6, 6, 6, 6);
 
 for (String text : list) {
    TextView textView = new TextView(this);
    textView.setBackgroundResource(R.drawable.bg_text);
    textView.setGravity(Gravity.CENTER);
    textView.setPadding(6, 6, 6, 6);
    textView.setText(text);
    textView.setTextSize(20);
    flowLayout.addView(textView);
   }
 
 setContentView(flowLayout);
 } 
 }

<shape xmlns:android="http://schemas.android.com/apk/res/android" 
 android:shape="rectangle">
 <stroke android:width="1dp"
  android:color="#5000" />
 <corners android:radius="6dp"/>
</shape>