Android从源码层100%屏幕适配

1.首先写一个获取比例的工具类

public class AutoUtils {
    private  Context context;
    private  static  AutoUtils instance;
    //标准值
    public static final float STANDARD_WIDTH=1080f;
    public static final float STANDARD_HEIGHT=1920f;
    //实际设备信息
    public static float displayMetriceWidth;
    public static float displayMetriceHight;

    public static AutoUtils getInstance(Context context){
        if (instance==null){
            instance=new AutoUtils(context);
        }
        return instance;
    }
    private AutoUtils(Context context){
        this.context=context;
        WindowManager windowManager= (WindowManager) context.getSystemService(
                Context.WINDOW_SERVICE);
        DisplayMetrics displayMetrics=new DisplayMetrics();
        if (displayMetriceWidth==0.0f||displayMetriceHight==0.0f){
            windowManager.getDefaultDisplay().getMetrics(displayMetrics);
            int systemBarHeight = getStatusBarHeight(context);
            if(displayMetrics.widthPixels>displayMetrics.heightPixels){
                displayMetriceWidth=(float) (displayMetrics.heightPixels);
                displayMetriceHight=(float) (displayMetrics.widthPixels-systemBarHeight);
            }else {
                displayMetriceWidth=(float) (displayMetrics.widthPixels);
                displayMetriceHight=(float) (displayMetrics.heightPixels-systemBarHeight);
            }
        }
    }
    public float getHorizontalScaleValue(){
        return ((float)displayMetriceWidth)/STANDARD_WIDTH;
    }
    public float getVertivaScaleValue(){
        return ((float)(displayMetriceHight)/STANDARD_HEIGHT);
    }
    /**
     * 获取状态栏高度
     *
     * @param context
     * @return
     */
    public static int getStatusBarHeight(Context context) {
        Resources resources = context.getResources();
        int resourceId = resources.getIdentifier("status_bar_height", "dimen", "android");
        int statusBarHeight = resources.getDimensionPixelSize(resourceId);
        return statusBarHeight;
    }
}

2.自定义布局，按照比例来计算组件的宽高

public class AutoRelativeLayout extends RelativeLayout {
    private boolean flag = true;
    public AutoRelativeLayout(Context context) {
        super(context);
    }
    public AutoRelativeLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public AutoRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed,l,t,r,b);
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    //保证值测量一次，查看源码会发现父类也会调用child.onMeasure()方法
       if(flag){
           float scaleX = AutoUtils.getInstance(getContext()).getHorizontalScaleValue();
           float scaleY = AutoUtils.getInstance(getContext()).getVertivaScaleValue();

           int childCount = this.getChildCount();

           for (int i = 0; i < childCount ; i++) {
               View child = getChildAt(i);
               LayoutParams layoutParams = (LayoutParams) child.getLayoutParams();
               layoutParams.width = (int)(layoutParams.width * scaleX);
               layoutParams.height= (int)(layoutParams.height * scaleY);
               layoutParams. leftMargin = (int) (layoutParams. leftMargin * scaleX);
               layoutParams. rightMargin = (int) (layoutParams. rightMargin * scaleX);
               layoutParams. topMargin = (int) (layoutParams. topMargin * scaleY) ;
               layoutParams. bottomMargin = (int) (layoutParams. bottomMargin * scaleY);
           }
       }
       flag=false;
       super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
    }
}