private String quote(String string) {
        StringWriter sw = new StringWriter();
        try {
            return quote(string, sw).toString();
        } catch (IOException ignored) {
            return "";
        }
    }
@author Robert HG (254963746@qq.com) on 12/28/15.
lts-core/src/main/java/com/github/ltsopensource/json/JSONObject.java