dp、sp与px的转换

float scale = context.getResources().getDisplayMetrics().density;
在分辨率为720*1280的手机上，scale的值为2，对应密度xhdpi

//dp转px
public static int dp2px(Context context, float dpValue) {
        float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
   }

//px转dp
public static int px2dp(Context context, float pxValue) {
        float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue /scale + 0.5f);
   }

//sp转
public static int sp2px(Context context, float spValue) {  
            float fontScale = context.getResources().getDisplayMetrics().scaledDensity;  
            return (int) (spValue * fontScale + 0.5f);  
    }