項目中需要實現正常情況下一種默認色彩，獲取焦點后下劃線變色，如果失去焦點，檢驗輸入值改變顏色。我們知道下劃線是EditText的background，那么可以給它一個background并設置在不同的狀態下改變background的值。

background使用shape繪制

<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item  android:id="@+id/shape"
        android:bottom="1dp"
        android:left="-10dp"
        android:right="-10dp"
        android:top="-10dp">
        <shape>
            <solid android:color="@android:color/transparent"/>
            <stroke android:width="1dp" android:color="@color/color_f1f1f1"/>
        </shape>
    </item>
</layer-list>

EditText

public class AddressEditText extends EditText implements View.OnFocusChangeListener {
    private Context context;


    public void setOnCheckInputListener(OnCheckInputListener onCheckInputListener) {
        this.onCheckInputListener = onCheckInputListener;
    }

    private OnCheckInputListener onCheckInputListener;
    private GradientDrawable     drawable;

    /**
     * 檢測輸入是否符合要求的回調
     */
    public interface OnCheckInputListener {
        /**
         * 檢測輸入的方法
         *
         * @param v   點擊的view
         * @param str 輸入的字符串
         * @return 檢測成功返回true, 檢測失敗返回false
         */
        boolean checkInput(View v, String str);
    }

    public AddressEditText(Context context) {
        this(context, null);
    }

    public AddressEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        LayerDrawable layerDrawable = (LayerDrawable) getBackground();
        drawable = (GradientDrawable) layerDrawable.findDrawableByLayerId(R.id.shape);
        setOnFocusChangeListener(this);
    }


    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if (hasFocus) {
            LogUtil.i("獲取焦點");
            drawable.setStroke(ResourceUtil.getDimens(R.dimen.dp_1), ResourceUtil.getColor(R.color.color_d1d1d1));
        } else {
            LogUtil.i("失去焦點");

            if (onCheckInputListener != null && onCheckInputListener.checkInput(this, getText().toString().trim())) {
                drawable.setStroke(ResourceUtil.getDimens(R.dimen.dp_1), ResourceUtil.getColor(R.color.color_f1f1f1));

            } else if (onCheckInputListener == null) {
                drawable.setStroke(ResourceUtil.getDimens(R.dimen.dp_1), ResourceUtil.getColor(R.color.color_f1f1f1));
            } else {
                drawable.setStroke(ResourceUtil.getDimens(R.dimen.dp_1), ResourceUtil.getColor(R.color.color_ff6f00));

            }
        }
    }
}