效果.gif

     <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="@dimen/dp_40"
        android:layout_marginLeft="@dimen/dp_12"
        android:layout_marginRight="@dimen/dp_12"
        android:layout_marginTop="@dimen/dp_12"
        android:background="@drawable/bg_white"
        android:orientation="horizontal">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:paddingLeft="@dimen/dp_10"
            android:text="消费金额："
            android:textColor="@color/title_color"
            android:textSize="@dimen/sp_14" />

        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/tv_buf"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginRight="@dimen/dp_10"
                android:gravity="center|right"
                android:text="￥"
                android:textColor="@color/shop_guige"
                android:textSize="@dimen/sp_20"
                android:visibility="gone" />

            <EditText
                android:id="@+id/dealMoney_et"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_alignParentRight="true"
                android:background="@null"
                android:gravity="right|center"
                android:inputType="number|numberDecimal"
                android:paddingLeft="@dimen/dp_5"
                android:paddingRight="@dimen/dp_10"
                android:textColor="@color/shop_guige"
                //@null表示和文字颜色一样
                android:textCursorDrawable="@null"
                android:textSize="@dimen/sp_14" />

            <TextView
                android:id="@+id/tv_hint"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginRight="8dp"
                android:background="@null"
                android:gravity="right|center_vertical"
                android:text="@string/询问服务员后输入"
                android:textColor="@color/third_txt_color"
                android:textSize="@dimen/sp_14" />

        </FrameLayout>

    </LinearLayout>

screenshot-1510135622138.jpg

1.输入过滤器InputFilter约束用户输入

public class CashierInputFilter implements InputFilter {
    Pattern mPattern;

    //输入的最大金额
    private static final int MAX_VALUE = 100000;
    //小数点后的位数
    private static final int POINTER_LENGTH = 2;

    private static final String POINTER = ".";

    private static final String ZERO = "0";
    //只能输入数字和小数点
    public CashierInputFilter() {
        mPattern = Pattern.compile("([0-9]|\\.)*");
    }

    /**
     * @param source 新输入的字符串
     * @param start  新输入的字符串起始下标，一般为0
     * @param end    新输入的字符串终点下标，一般为source长度-1
     * @param dest   输入之前文本框内容
     * @param dstart 原内容起始坐标，一般为0
     * @param dend   原内容终点坐标，一般为dest长度-1
     * @return 输入内容
     */
    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        String sourceText = source.toString();
        String destText = dest.toString();

        //验证删除等按键
        if (TextUtils.isEmpty(sourceText)) {
            return "";
        }

        Matcher matcher = mPattern.matcher(source);
        //已经输入小数点的情况下，只能输入数字
        if (destText.contains(POINTER)) {
            if (!matcher.matches()) {
                return "";
            } else {
                if (POINTER.equals(source.toString())) {  //只能输入一个小数点
                    return "";
                }
            }

            //验证小数点精度，保证小数点后只能输入两位
            int index = destText.indexOf(POINTER);
            int length = dend - index;

            if (length > POINTER_LENGTH) {
                return dest.subSequence(dstart, dend);
            }
        } else {
            /**
             * 没有输入小数点的情况下，只能输入小数点和数字
             * 1. 首位不能输入小数点
             * 2. 如果首位输入0，则接下来只能输入小数点了
             */
            if (!matcher.matches()) {
                return "";
            } else {
                if ((POINTER.equals(source.toString())) && TextUtils.isEmpty(destText)) {  //首位不能输入小数点
                    return "";
                } else if (!POINTER.equals(source.toString()) && ZERO.equals(destText)) { //如果首位输入0，接下来只能输入小数点
                    return "";
                }
            }
        }

        //验证输入金额的大小
        double sumText = Double.parseDouble(destText + sourceText);
        if (sumText > MAX_VALUE) {
            return dest.subSequence(dstart, dend);
        }

        return dest.subSequence(dstart, dend) + sourceText;
    }
}

在Activity中的代码

InputFilter[] filters = {new CashierInputFilter()};
etDealMoney.setFilters(filters);
NoConcessionsMoneyEd.setFilters(filters);

      /**
         * 监听消费金额的输入
         */
        dealMoneyTv.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                conPrice = s.toString();
                int bg = TextUtils.isEmpty(s) ? R.drawable.selector_tuan__offer_to_pay_butn_bg : R.drawable.tuan_red_bag;
                SubmitButtonTv.setBackground(getResources().getDrawable(bg));
                SubmitButtonTv.setEnabled(TextUtils.isEmpty(s) ? false : true);
                dealWithMone(conPrice, notEnjoy);
            }

            @Override
            public void afterTextChanged(Editable s) {
                if (s.length() > 0) {
                    //设置不享受优惠编辑框可以编辑
                    NoConcessionsMoneyEd.setMoneyIsEmpty(false);
                    //显示消费金额的￥
                    tvBuf.setVisibility(View.VISIBLE);
                    //获取EditText内容长度
                    float textWidth = getTextWidth(dealMoneyTv);
                    //通过setX(float x)让￥往左移动
                    tvBuf.setX(-textWidth);
                    //隐藏hint
                    tvHint.setVisibility(View.GONE);
                } else {
                    NoConcessionsMoneyEd.setMoneyIsEmpty(true);
                    tvBuf.setVisibility(View.GONE);
                    tvHint.setVisibility(View.VISIBLE);
                }
            }

      /**
         * 监听不享受优惠金额的输入
         */
        NoConcessionsMoneyEd.setOnFocusChangeListener((v, hasFocus) -> {
            //不享受优惠金额的焦点
            noconcessionsFocus = hasFocus;
        });

        NoConcessionsMoneyEd.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                //不享受优惠金额
                notEnjoy = s.toString();
                if (!TextUtils.isEmpty(conPrice)) {
                    dealWithMone(conPrice, notEnjoy);
                }
            }

            @Override
            public void afterTextChanged(Editable s) {
                if (s.length() > 0) {
                    //不享受优惠金额￥显示
                    tvSymbol.setVisibility(View.VISIBLE);
                    //获取内容长度
                    float textWidth = getTextWidth(NoConcessionsMoneyEd);
                    tvSymbol.setX(-textWidth);
                } else {
                    tvSymbol.setVisibility(View.GONE);
                }
            }
        });

不享受优惠金额这里使用了自定义EditText

public class MyEditText extends EditText {
    /**
     * 消费金额是否为空
     * 默认为true
     */
    private boolean isEmpty = true;

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

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

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

    }

    @Override
    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
        return new InputConnecttion(super.onCreateInputConnection(outAttrs), false);

    }

    /**
     * 消费金额是否为空
     *
     * @param isEmpty
     */
    public void setMoneyIsEmpty(boolean isEmpty) {
        this.isEmpty = isEmpty;
    }

    class InputConnecttion extends InputConnectionWrapper implements
            InputConnection {

        public InputConnecttion(InputConnection target, boolean mutable) {
            super(target, mutable);
        }

        /**
         * 对输入的内容进行拦截
         *
         * @param text
         * @param newCursorPosition
         * @return
         */
        @Override
        public boolean commitText(CharSequence text, int newCursorPosition) {
            // 当消费金额为空的时候进行拦截
            if (isEmpty) {
                ToastUtil.show("请先填写消费金额");
                return false;
            }
            return super.commitText(text, newCursorPosition);
        }

        @Override
        public boolean sendKeyEvent(KeyEvent event) {
            return super.sendKeyEvent(event);
        }

        @Override
        public boolean setSelection(int start, int end) {
            return super.setSelection(start, end);
        }
    }
}

/**
     * 获取EditText的内容宽度
     * @param editText
     * @return
     */
    private float getTextWidth(EditText editText) {
        TextPaint mTextPaint = editText.getPaint();
        return mTextPaint.measureText(editText.getText().toString());
    }