1，引言：刚从国庆长假的放荡中醒过来，已经有将近十天没碰电脑了，上午写写代码感觉手还是挺生的，想把自定义view好好的系统的学学，在网上看了看别人出的教程 ，stay4it的自定义view感觉还是挺好的，就打算按照这个课程好好学习学习。并打算用blog记录下来（主要怕自己忘记嘛）

 

2， 今天这个简单的自定义view是在网上看的，就是实现其内所有的view放置在上下左右的顺序进行排列，然后简单的跟着别人的思路写了些，效果图如下：

不多说了 直接上代码  ，主要是重写了OnMeasure（）和OnDraw（）方法

MyFourTextViewGroup.Class

package com.wangjitao.myview.view;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.View;import android.view.ViewGroup;/** * Created by wangjitao on 2016/10/8 0008. * 当内部传入TextView的时候依次显示在上下左右的四个角 */public class MyFourTextViewGroup extends ViewGroup {    public MyFourTextViewGroup(Context context) {        super(context);    }    public MyFourTextViewGroup(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MyFourTextViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    /**     * 1,重写generateLayoutParams是view支持margin     *     * @param attrs     * @return     */    @Override    public LayoutParams generateLayoutParams(AttributeSet attrs) {        return new MarginLayoutParams(getContext(), attrs);    }    /**     * 计算所有子view的宽度和高度，根据ChildView的计算解雇，设置自己的宽和高     *     * @param widthMeasureSpec     * @param heightMeasureSpec     */    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        /**         * 获得此viewGroup上级容器为其推荐的高和宽，以及计算的方式         */        int widthMode = MeasureSpec.getMode(widthMeasureSpec);        int heightMode = MeasureSpec.getMode(heightMeasureSpec);        int widthSize = MeasureSpec.getSize(widthMeasureSpec);        int heightSize = MeasureSpec.getSize(heightMeasureSpec);        //计算出所有的childView的设置的宽和高        measureChildren(widthMeasureSpec, heightMeasureSpec);        /**         * 记录如果是wrap_content设置的宽和高         */        int width = 0;        int height = 0;        int childCount = getChildCount();        int childWidth = 0;        int childHeight = 0;        MarginLayoutParams childParams = null;        //用于计算左边两个childView的高度        int leftHeight = 0;        //用于计算右边两个childView的高度,最终高度取二者之间的最大值        int rightHeight = 0;        //用于取上面两个childView的宽度        int topWidth = 0;        //计算下面两个chideView的宽高，取二者之间的最大值        int bottomWidth = 0;        /**         * 根据childView计算出来的宽度和高度，以及设置的margin计算容器的宽和高，主要用于容器的wrap_content         */        for (int i = 0; i < childCount; i++) {            View childView = getChildAt(i);            childWidth = childView.getMeasuredWidth();            childHeight = childView.getMeasuredHeight();            childParams = (MarginLayoutParams) childView.getLayoutParams();            //上面的两个Childview比较的是宽度            if (i == 0 || i == 1) {                topWidth += childWidth + childParams.leftMargin + childParams.rightMargin;            }            if (i == 2 || i == 3) {                bottomWidth += childWidth + childParams.leftMargin + childParams.rightMargin;            }            //左边的两个childView比较的是高度            if (i == 0 || i == 2) {                leftHeight += childHeight + childParams.topMargin + childParams.bottomMargin;            }            if (i == 0 || i == 2) {                rightHeight += childHeight + childParams.topMargin + childParams.bottomMargin;            }        }        width = Math.max(topWidth, bottomWidth);        height = Math.max(leftHeight, rightHeight);        //如果是wrap_content则设置为我们计算的值，否的话则设置为父容器计算的值        setMeasuredDimension((widthMode == MeasureSpec.EXACTLY) ? widthSize : width,                (heightMode == MeasureSpec.EXACTLY) ? heightSize : height);    }    /**     * 用来给所有的childView进行定位     */    @Override    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {        int childCount = getChildCount();        int childWidth = 0;        int childHeight = 0;        MarginLayoutParams childParams = null;        /**         * 遍历所有childView根据其高和宽，以及margin进行布局         */        for (int i = 0; i < childCount; i++) {            View childView = getChildAt(i);            childWidth = childView.getMeasuredWidth();            childHeight = childView.getMeasuredHeight();            childParams = (MarginLayoutParams) childView.getLayoutParams();            int childLeft = 0;            int childTop = 0;            int childRight = 0;            int childBottom = 0;            switch (i) {                case 0:                    childLeft = childParams.leftMargin;                    childTop = childParams.topMargin;                    break;                case 1:                    Log.i("wangjitao", "getWidth():" + getWidth() + ",childWidth :" + childWidth                            + ",childParams.leftMargin:" + childParams.leftMargin);                    childLeft = getWidth() - childWidth -                            childParams.leftMargin - childParams.rightMargin;                    childTop = childParams.topMargin;                    break;                case 2:                    childLeft = childParams.leftMargin;                    childTop = getHeight() - childHeight - childParams.bottomMargin;                    break;                case 3:                    childLeft = getWidth() - childWidth -                            childParams.leftMargin - childParams.rightMargin;                    childTop = getHeight() - childHeight - childParams.bottomMargin;                    break;            }            childRight = childLeft + childWidth;            childBottom = childHeight + childTop;            childView.layout(childLeft, childTop, childRight, childBottom);        }    }}