import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by TONG on 2017/3/19.
 */

public class MyView extends View {

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec));
    }

    private int measureHeight(int measureSpec) {
        int result;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        //match_parent 具体值
        if(specMode==MeasureSpec.EXACTLY){
            result=specSize;
        }else{
            result=100;
            //wrap_content
            if(specMode==MeasureSpec.AT_MOST){
                result=Math.min(result,specSize);
            }
        }
        return result;
    }

    private int measureWidth(int measureSpec) {
        int result;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        if(specMode==MeasureSpec.EXACTLY){
            result=specSize;
        }else {
            result=200;
            if(specMode==MeasureSpec.AT_MOST){
                result=Math.min(result,specSize);
            }
        }
        return result;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        setBackgroundColor(getResources().getColor(android.R.color.holo_blue_light));
    }
}

Paste_Image.png