json 需替换 特殊字符串
sourceStr = sourceStr.Replace("\b", "\\\b");
sourceStr = sourceStr.Replace("\t", "\\\t");
sourceStr = sourceStr.Replace("\n", "\\\n");
sourceStr = sourceStr.Replace("\f", "\\\f");
sourceStr = sourceStr.Replace("\r", "\\\r");
return sourceStr.Replace("\"", "\\\"");
完