效果图

布局文件

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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:layout_width="match_parent" android:layout_height="100dp" android:background="#003839" android:gravity="center" android:visibility="visible" android:text="SECOND"/> <com.pengkv.apple.weight.FirstView android:layout_width="wrap_content" android:visibility="visible" android:background="#888787" android:layout_height="wrap_content"/> </LinearLayout>

View代码

public class FirstView extends LinearLayout {
          public FirstView(Context context) {
     //代码实例化的时候调用        super(context);    }    public FirstView(Context context, AttributeSet attrs) {
     //布局文件引用的时候调用        super(context, attrs);    }    public FirstView(Context context, AttributeSet attrs, int defStyleAttr) {
     //自己定义属性值的时候调用        super(context, attrs, defStyleAttr);    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {//        super.onMeasure(widthMeasureSpec,heightMeasureSpec);        setMeasuredDimension(measureSpec(widthMeasureSpec),measureSpec(heightMeasureSpec)); //重測尺寸    }    public int measureSpec(int measureSpec){        int result=0;        int specMode=MeasureSpec.getMode(measureSpec);//获取測量模式        int specSize=MeasureSpec.getSize(measureSpec);//获取測量尺寸        if (specMode==MeasureSpec.EXACTLY){
     //精确模式：包含准确设置dp值和match_parent            result=specSize;        }else {            result=400;//默认设置的尺寸            if (specMode==MeasureSpec.AT_MOST){                result=Math.min(result,specSize);            }        }        return result;    }}