public float floatValue() {
        String strVal = numberString();
        float floatValue = Float.parseFloat(strVal);
        if (floatValue == 0 || floatValue == Float.POSITIVE_INFINITY) {
            char c0 = strVal.charAt(0);
            if (c0 > '0' && c0 <= '9') {
                throw new JSONException("float overflow : " + strVal);
            }
        }
        return floatValue;
    }
internal method, don't invoke
@param token
src/main/java/com/alibaba/fastjson/parser/JSONLexerBase.java