Android 简单实现一个流式布局的示例

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    // 获得它的父容器为它设置的测量模式和大小
    int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
    int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
    int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
    int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

    // 如果是warp_content情况下，记录宽和高
    int width = 0;
    int height = 0;

    //记录每一行的宽度，width不断取最大宽度
    int lineWidth = 0;
    //记录每一行的宽度，不断累加每行最大高度获取height
    int lineHeight = 0;

    //获取子View的数量
    int childCount = getChildCount();
    //遍历每个子元素
    for (int i = 0; i < childCount; i++) {
      //获取每一个子View
      View childView = getChildAt(i);
      //测量每一个子View的宽和高
      measureChild(childView,widthMeasureSpec,heightMeasureSpec);
      //得到子View的lp
      LayoutParam lp = (LayoutParam) childView.getLayoutParams();
      //当前子View实际占据的宽度
      int childWidth = childView.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
      //当前子View实际占据的高度
      int childHeight = childView.getMeasuredHeight() + lp.bottomMargin + lp.topMargin;

      //如果加入当前childView，超出最大宽度，则得到目前最大宽度给width，类加height 然后开启新行
      if (lineWidth + childWidth > sizeWidth) {
        // 取最大的宽度
        width = Math.max(lineWidth, childWidth);
        //重新开启新行，重新计算
        lineWidth = childWidth;
        //叠加当前高度
        height += childHeight;
        //记录下一行高度
        lineHeight = childHeight;
      }else {
        // 累加值lineWidth,lineHeight取最大高度
        lineWidth += childWidth;
        lineHeight = Math.max(lineHeight,childHeight);
      }
      // 如果是最后一个，则将当前记录的最大宽度和当前lineWidth做比较
      if (i == childCount - 1) {
        width = Math.max(width,lineWidth);
        height += lineHeight;
      }
    }
    setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY?sizeWidth:width,modeHeight == MeasureSpec.EXACTLY?sizeHeight:height);
  }

  //存储所有的View，按行记录
  private List<List<View>> mAllViews = new ArrayList<>();
  //记录每一行的最大高度
  private List<Integer> mLineHeight = new ArrayList<>();
  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    mAllViews.clear();
    mLineHeight.clear();

    int lineWidth = 0;
    int lineHeight = 0;

    int width = getWidth();

    int childCount = getChildCount();
    // 存储每一行所有的childView
    List<View> lineViews = new ArrayList<>();
    for (int i = 0; i < childCount; i++) {
      View childView = getChildAt(i);
      LayoutParam lp = (LayoutParam) childView.getLayoutParams();
      int childWidth = childView.getMeasuredWidth() + lp.rightMargin + lp.leftMargin;
      int childHeight = childView.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;

      if (lineWidth + childWidth > width) {
        // 记录这一行所有的View以及最大高度
        mLineHeight.add(lineHeight);
        // 将当前行的childView保存，然后开启新的ArrayList保存下一行的childView
        mAllViews.add(lineViews);
        lineWidth = 0;
        lineViews = new ArrayList<>();
      }
      //如果不需要换行，则累加
      lineWidth += childWidth;
      lineHeight = Math.max(lineHeight,childHeight);
      lineViews.add(childView);
    }
    // 记录最后一行
    mAllViews.add(lineViews);
    mLineHeight.add(lineHeight);

    int left = 0;
    int top = 0;

    // 得到总行数
    int size = mAllViews.size();

    for (int i = 0; i < size; i++) {
      // 每一行的所有的views
      lineViews = mAllViews.get(i);
      // 当前行的最大高度
      lineHeight = mLineHeight.get(i);

      for (View view : lineViews) {
        LayoutParam lp = (LayoutParam) view.getLayoutParams();
        //计算childView的left,top,right,bottom
        int lc = left + lp.leftMargin;
        int tc = top + lp.topMargin;
        int rc = lc + view.getMeasuredWidth();
        int bc = tc + view.getMeasuredHeight();
        view.layout(lc,tc,rc,bc);
        left += view.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
      }
      left = 0;
      top += lineHeight;
    }
  }

public class MainActivity extends AppCompatActivity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    FlowLayout flowLayout = ((FlowLayout) findViewById(R.id.flowLayout));
    FlowLayout.LayoutParam params = new    FlowLayout.LayoutParam(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    params.setMargins(10,10,10,10);
    for (int i = 0; i < 10; i++) {
      TextView textView = new TextView(this);
      textView.setPadding(i * 10,10,i * 10,10);
      textView.setBackgroundColor(Color.BLUE);
      textView.setText("哈哈哈哈");
      textView.setTextColor(Color.WHITE);
      textView.setLayoutParams(params);
      flowLayout.addView(textView);
    }
  }
}

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

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

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

  public static class LayoutParam extends MarginLayoutParams{

    public LayoutParam(Context c, AttributeSet attrs) {
      super(c, attrs);
    }

    public LayoutParam(@Px int width, @Px int height) {
      super(width, height);
    }

    public LayoutParam(MarginLayoutParams source) {
      super(source);
    }

    public LayoutParam(LayoutParams source) {
      super(source);
    }
  }