public String scanFieldString(char[] fieldName) {
        matchStat = UNKNOWN;

        if (!charArrayCompare(fieldName)) {
            matchStat = NOT_MATCH_NAME;
            return stringDefaultValue();
        }

        // int index = bp + fieldName.length;

        int offset = fieldName.length;
        char chLocal = charAt(bp + (offset++));

        if (chLocal != '"') {
            matchStat = NOT_MATCH;

            return stringDefaultValue();
        }

        final String strVal;
        {
            int startIndex = bp + fieldName.length + 1;
            int endIndex = indexOf('"', startIndex);
            if (endIndex == -1) {
                throw new JSONException("unclosed str");
            }

            int startIndex2 = bp + fieldName.length + 1; // must re compute
            String stringVal = subString(startIndex2, endIndex - startIndex2);
            if (stringVal.indexOf('\\') != -1) {
                for (;;) {
                    int slashCount = 0;
                    for (int i = endIndex - 1; i >= 0; --i) {
                        if (charAt(i) == '\\') {
                            slashCount++;
                        } else {
                            break;
                        }
                    }
                    if (slashCount % 2 == 0) {
                        break;
                    }
                    endIndex = indexOf('"', endIndex + 1);
                }

                int chars_len = endIndex - (bp + fieldName.length + 1);
                char[] chars = sub_chars( bp + fieldName.length + 1, chars_len);

                stringVal = readString(chars, chars_len);
            }

            offset += (endIndex - (bp + fieldName.length + 1) + 1);
            chLocal = charAt(bp + (offset++));
            strVal = stringVal;
        }

        if (chLocal == ',') {
            bp += offset;
            this.ch = this.charAt(bp);
            matchStat = VALUE;
            return strVal;
        }

        if (chLocal == '}') {
            chLocal = charAt(bp + (offset++));
            if (chLocal == ',') {
                token = JSONToken.COMMA;
                bp += offset;
                this.ch = this.charAt(bp);
            } else if (chLocal == ']') {
                token = JSONToken.RBRACKET;
                bp += offset;
                this.ch = this.charAt(bp);
            } else if (chLocal == '}') {
                token = JSONToken.RBRACE;
                bp += offset;
                this.ch = this.charAt(bp);
            } else if (chLocal == EOI) {
                token = JSONToken.EOF;
                bp += (offset - 1);
                ch = EOI;
            } else {
                matchStat = NOT_MATCH;
                return stringDefaultValue();
            }
            matchStat = END;
        } else {
            matchStat = NOT_MATCH;
            return stringDefaultValue();
        }

        return strVal;
    }
internal method, don't invoke
@param token
src/main/java/com/alibaba/fastjson/parser/JSONLexerBase.java