用Jackson将对象转储到String

与杰克逊连载：

public String serialize(Object obj, boolean pretty) {    ObjectMapper mapper = new ObjectMapper();    mapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false);    if (pretty) {        return mapper.writerWithDefaultPrettyPrinter().writevalueAsString(obj);    }    return mapper.writevalueAsString(obj);}