自定义流布局

package cn.com.xiebiao.flowlayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by vibexie on 3/26/15.
 */
public class FlowLayout extends ViewGroup{

    //三个构造方法
    public FlowLayout(Context context) {
        //super(context);
        this(context,null);
    }

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

    }

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

    //当前ViewGroup对应的LayoutParams
    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new MarginLayoutParams(getContext(),attrs);
    }

    /*widthMeasureSpec,heightMeasureSpec分别为
     *android:layout_width="match_parent" android:layout_height="match_parent">
     * 也就是父ViewGroup传递进来的值
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        /*容器ViewGroup的宽度和模式，android:layout_width="match_parent"对应模式MeasureSpec.EXACTLY;
          android:layout_width="match_parent"对应模式MeasureSpec.AT_MOST;
          还有一种模式不常用MeasureSpec.UNSPECIFIED
         */
        int sizeWidth=MeasureSpec.getSize(widthMeasureSpec);
        int modeWidth=MeasureSpec.getMode(widthMeasureSpec);
        /*容器ViewGroup的宽度和模式，同width*/
        int sizeHeigth=MeasureSpec.getSize(heightMeasureSpec);
        int modeHeigth=MeasureSpec.getMode(heightMeasureSpec);

        /*如上，是match_parent的时候，sizeWidth和sizeHeigth可以在父viewGroup中得到
             但是如果是warp_content时，就需要自己计算sizeWidth和sizeHeigth
             */
        //记录最大宽度和最大高度对应的宽和高
        int width=0;
        int heigth=0;
        //记录每一行的宽度和高度
        int lineWidth=0;
        int lineHeigth=0;
        //得到内部元素的个数
        int cCount=getChildCount();

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

            /*测量子view的宽和高
              protected void measureChild(android.view.View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec)
             */
            measureChild(child,widthMeasureSpec,heightMeasureSpec);

            /*得到LayoutParams,必须由于父View的LayoutParams相一致，
              即与public LayoutParams generateLayoutParams(AttributeSet attrs)返回的一致
              */
            MarginLayoutParams layoutParams=(MarginLayoutParams)child.getLayoutParams();

            //子View占据的宽度
            int childWidth=child.getMeasuredWidth()+layoutParams.leftMargin+layoutParams.rightMargin;
            //子View占据的高度
            int childHeigth=child.getMeasuredHeight()+layoutParams.topMargin+layoutParams.bottomMargin;

            if((lineWidth+childWidth)>sizeWidth){
                //如果此行的宽度+下一个子View的宽度大于容器ViewGroup的宽度，则换行
                //记录的最大宽度width和本行的宽度lineWidth比较，得到最大的宽度再记录
                width=Math.max(width,lineWidth);
                //重置lineWidth
                lineWidth=childWidth;
                //记录行高
                heigth+=lineHeigth;
                //重置lineHeigth
                lineHeigth=childHeigth;
            }else {
                //不换行
                //叠加行宽
                lineWidth+=childWidth;
                //得到当前行最到的高度
                lineHeigth=Math.max(lineHeigth,childHeigth);
            }

            if(i==cCount-1){
                //到达最后一个子view
                width=Math.max(lineWidth,width);
                heigth+=lineHeigth;
            }
        }

        //设定最终尺寸
        setMeasuredDimension(modeWidth==MeasureSpec.EXACTLY?sizeWidth:width,modeHeigth==MeasureSpec.EXACTLY?sizeHeigth:heigth);

        //super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    //保存所有的View,以分行的方式保存
    private List<List<View>> mAllViews=new ArrayList<List<View>>();

    //每一行的高度
    private List<Integer> mLineHeigth=new ArrayList<Integer>();

    @Override
    protected void onLayout(boolean b, int i, int i2, int i3, int i4) {
        //调用多次onlayout方法时，清空保存的内容
        mAllViews.clear();
        mLineHeigth.clear();

        //当前ViewGroup的宽度，之前已经执行了onMesure()方法
        int width=getWidth();

        int lineWidth=0;
        int lineHeigth=0;

        //存放每一行的View
        List<View> lineViews=new ArrayList<View>();

        //子View的个数
        int cCount=getChildCount();

        for(int j=0;j<cCount;j++){
            View child=getChildAt(j);
            MarginLayoutParams layoutParams=(MarginLayoutParams)child.getLayoutParams();

            int childWidth=child.getMeasuredWidth();
            int childHeigth=child.getMeasuredHeight();

            //如果需要换行
            if((childWidth+lineWidth+layoutParams.leftMargin+layoutParams.rightMargin)>width){
                //记录lineHeigth
                mLineHeigth.add(lineHeigth);
                //记录当前的view
                mAllViews.add(lineViews);

                //重置行宽和行高
                lineWidth=0;
                lineHeigth=childHeigth+layoutParams.topMargin+layoutParams.bottomMargin;

                //重置lineViews集合
                lineViews=new ArrayList<View>();
            }

            //不换行则将child加入lineViews中
            lineWidth+=childWidth+layoutParams.leftMargin+layoutParams.rightMargin;
            lineHeigth=Math.max(lineHeigth,childHeigth+layoutParams.topMargin+layoutParams.bottomMargin);
            lineViews.add(child);
        }

        //处理最后一行
        mLineHeigth.add(lineHeigth);
        mAllViews.add(lineViews);


        //处理子View的位置
        int left=0;
        int top=0;

        //行数
        int lineNum=mAllViews.size();

        for(int j=0;j<lineNum;j++){
            //当前行的所有View
            lineViews=mAllViews.get(j);
            lineHeigth=mLineHeigth.get(j);

            for(int k=0;k<lineViews.size();k++){
                View child=lineViews.get(k);

                //判断child的状态
                if(child.getVisibility()==View.GONE){
                    continue;
                }

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

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

                //为子View布局
                child.layout(lc,tc,rc,bc);

                left+=child.getMeasuredWidth()+layoutParams.leftMargin+layoutParams.rightMargin;
            }

            //到达下一行
            left=0;
            top+=lineHeigth;
        }
    }
}

<RelativeLayout xmlns:android=""
    xmlns:tools="" android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <cn.com.xiebiao.flowlayout.FlowLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="hello"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="welocom"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="fdsfsd"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="fdsfdsgdgdfgdfgf"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ghfdhdgfhdfghdgfh"/>
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ggg"/>

    </cn.com.xiebiao.flowlayout.FlowLayout>

</RelativeLayout>

package cn.com.xiebiao.flowlayout;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;


public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}