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);    }  }