Stream string values

JsonWriter.java

    class StringWriter extends Writer {
        public StringWriter(Writer out) {
            this.out = out;
        }

        @Override
        public void write(char[] cbuf, int off, int len) throws IOException {
            for (int i = 0; i < len; i++) {
                char c = cbuf[i + off];
                /*
                 * From RFC 4627, "All Unicode characters may be placed within the
                 * quotation marks except for the characters that must be escaped:
                 * quotation mark, reverse solidus, and the control characters
                 * (U+0000 through U+001F)."
                 *
                 * We also escape '\u2028' and '\u2029', which JavaScript interprets
                 * as newline characters. This prevents eval() from failing with a
                 * syntax error.
                 * http://code.google.com/p/google-gson/issues/detail?id=341
                 */
                switch (c) {
                    case '"':
                    case '\\':
                        out.write('\\');
                        out.write(c);
                        break;
                    case '\t':
                        out.write("\\t");
                        break;
                    case '\b':
                        out.write("\\b");
                        break;
                    case '\n':
                        out.write("\\n");
                        break;
                    case '\r':
                        out.write("\\r");
                        break;
                    case '\f':
                        out.write("\\f");
                        break;
                    case '\u2028':
                    case '\u2029':
                        out.write(String.format("\\u%04x", (int) c));
                        break;
                    default:
                        if (c <= 0x1F) {
                            out.write(String.format("\\u%04x", (int) c));
                        } else {
                            out.write(c);
                        }
                        break;
                }
            }
        }
        @Override
        public void flush() throws IOException {
            out.flush();
        }
        @Override
        public void close() throws IOException {
            out.write("\"");
        }
        Writer out;
    }

    public StringWriter writeString() throws IOException {
        beforeValue(false);

        out.write("\"");
        StringWriter stringWriter = new StringWriter(out);
        return stringWriter;
    }