需求：輸入框和文本顯示框，單行的時候文字靠右，多行的時候文字靠左

最優(yōu)解

public class  OrientionEditText extends EditText {

    public OrientionEditText (Context context) {
        super(context);
    }

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

    @Override protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (getLineCount() > 1) {//得到文本的行數(shù)
            setGravity(Gravity.LEFT);
        } else {
            setGravity(Gravity.RIGHT);
        }

        canvas.restore();
    }
}