输入框带删除按钮, 此乃标配, 实现起来方法也很多, 网上开源也很多.

但是, 没事就喜欢瞎折腾.

上图说话.

只是在原生的基础上加了扩展. 相对来说入侵非常少, 使用方法和原生的一模一样.无任何阉割.

完整代码:

public class ExEditText extends AppCompatEditText {

    Rect clearRect = new Rect();

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

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

    public ExEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        //在不影响默认过滤规则的情况下,添加Emoji表情过滤
        if ("emoji".equalsIgnoreCase(String.valueOf(getTag()))) {
            final InputFilter[] filters = getFilters();
            final InputFilter[] newFilters = new InputFilter[filters.length + 1];
            System.arraycopy(filters, 0, newFilters, 0, filters.length);
            newFilters[filters.length] = new EmojiFilter();
            setFilters(newFilters);
        }
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
        super.onFocusChanged(focused, direction, previouslyFocusedRect);
        //焦点改变,检查是否需要显示删除按钮
        checkEdit(focused);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //用来计算删除按钮所在的矩形区域
        clearRect.set(w - getPaddingRight() - Math.min(w, h), getPaddingTop(), w - getPaddingRight(), Math.min(w, h) - getPaddingBottom());
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //检查点击删除按钮区域,并且当前具有焦点
        if (event.getAction() == MotionEvent.ACTION_DOWN && isFocused()) {
            //检查是否在删除按钮矩形区域,按下
            if (checkClear(event.getX(), event.getY())) {
                //如果当前已经是空的, 不处理Touch事件,否则清空文本,达到删除的效果
                if (!TextUtils.isEmpty(getText())) {
                    setText("");
                    return true;
                }
            }
        }
        return super.onTouchEvent(event);
    }

    private void checkEdit(boolean focused) {
        if (TextUtils.isEmpty(getText()) || !focused) {
            setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0);
        } else {
            //这里才是关键, 用的是原生的方法显示删除图标.
            setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.base_edit_delete, 0);
        }
    }

    //坐标是否在按钮区
    private boolean checkClear(float x, float y) {
        return clearRect.contains(((int) x), (int) y);
    }

    @Override
    protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
        super.onTextChanged(text, start, lengthBefore, lengthAfter);
        //时刻检查一下
        checkEdit(true);
    }
}

Emoji表情过滤:

可能还是有些特殊的Emoji表情,或者字符表情无法过滤, 抱歉;
如果你发现, 请告知, 让我们一起完善一下, 谢谢!

public class EmojiFilter implements InputFilter {
    Pattern emojiPattern = Pattern.compile("[\ud83c\udc00-\ud83c\udfff]|[\ud83d\udc00-\ud83d\udfff]|[\u2600-\u27ff]",
            Pattern.UNICODE_CASE | Pattern.CASE_INSENSITIVE);
    private int mMax = -1;//默认不过滤长度

    public EmojiFilter() {
    }

    public EmojiFilter(int max) {
        mMax = max;
    }

    /**
     * 检测是否有emoji表情
     *
     * @param source
     * @return
     */
    public static boolean containsEmoji(CharSequence source) {
        int len = source.length();
        for (int i = 0; i < len; i++) {
            char codePoint = source.charAt(i);
            if (!isEmojiCharacter(codePoint)) { //如果不能匹配,则该字符是Emoji表情
                return true;
            }
        }
        return false;
    }

    /**
     * 判断是否是Emoji
     *
     * @param codePoint 比较的单个字符
     * @return
     */
    private static boolean isEmojiCharacter(char codePoint) {
        return (codePoint == 0x0) || (codePoint == 0x9) || (codePoint == 0xA) ||
                (codePoint == 0xD) || ((codePoint >= 0x20) && (codePoint <= 0xD7FF)) ||
                ((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) || ((codePoint >= 0x10000)
                && (codePoint <= 0x10FFFF));
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart,
                               int dend) {
        if (this.emojiPattern.matcher(source).find() || containsEmoji(source)) {
            return "";
        }

        if (mMax != -1) {
            int keep = mMax - (dest.length() - (dend - dstart));
            if (keep <= 0) {
                return "";
            } else if (keep >= end - start) {
                return null; // keep original
            } else {
                keep += start;
                if (Character.isHighSurrogate(source.charAt(keep - 1))) {
                    --keep;
                    if (keep == start) {
                        return "";
                    }
                }
                return source.subSequence(start, keep);
            }
        }

        return source;
    }
}

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