3

这是我的转换代码。当我们处理大数据时，这需要很长时间......调用该方法几乎一百万次......我们可以清楚地看到它正在持有线程一段时间。

请建议我一些提高性能的方法！

public class GenericObjectXMLConverter<T> {

  private T t = null;
  private static JAXBContext jaxbContext =null;
  public GenericObjectXMLConverter() {

  }
  public GenericObjectXMLConverter(T obj){
    t = obj;
  }

  protected final Logger  log = Logger.getLogger(getClass());

  /**
   * Converts the java Object and into a xml string message type.
   * @param object the object to convert
   * @return String the converted xml message as string
   */
  public String objectToXMLMessage(T object) {
    StringWriter stringWriter = new StringWriter();
    //JAXBContext jaxbContext=null;
    try {
      jaxbContext = JAXBContext.newInstance(object.getClass());
      Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
      jaxbMarshaller.marshal(object, stringWriter);
    } catch (JAXBException e) {
      log.warn("JAXBException occured while converting the java object into xml string :"+e.getMessage());
    }
       /*if(log.isDebugEnabled())
         log.debug("xml string after conversion:"+stringWriter.toString());*/
       return stringWriter.toString();
  }

  /**
   * Converts a xml string message into a Java Object
   * @param string the string message to convert
   * @return Object the result as Java Object. If the message parameter is null then
     *  this method will simply return null.
   */
  @SuppressWarnings("unchecked")
  public T xmlToObject(String message) {
    if(message.equals("") || message.equals(" ") || message.length()==0){
      return null;
    }else{
      T object=null;
      try {
        jaxbContext = JAXBContext.newInstance(t.getClass());
        StringReader reader = new StringReader(message);
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
        object = (T)jaxbUnmarshaller.unmarshal(reader);
        } catch (JAXBException e) {
        log.warn("JAXBException occured while converting the xml string into a Java Object :"+e.getMessage());
        }
       /* if(log.isDebugEnabled()){
          log.debug("Java object after conversion:"+object.toString());
        }*/
      return object;
    }
  }

}
4

2 回答 2

19

性能和 JAXB 运行时类

  • 您应该避免JAXBContext一遍又一遍地创建相同的内容。 JAXBContext是线程安全的，应该重复使用以提高性能。
  • Marshaller/Unmarshaller不是线程安全的，但可以快速创建。重复使用它们没什么大不了的。
于 2013-09-04T09:43:56.173 回答
5

JAXBContext您应该为每个 bean 类创建单个对象。这是我维护JAXBContext每个 bean 类的单例对象的版本。

public class MyJAXBUtil {
    public static final Map<String, JAXBContext> JAXB_MAP = new HashMap<>();
    public static JAXBContext getJAXBContext(Object object) {
        if(JAXB_MAP.get(object.getClass().getCanonicalName()) != null) {
            return JAXB_MAP.get(object.getClass().getCanonicalName());
        }else {
            try {
                JAXBContext jaxbContext = JAXBContext.newInstance(object.getClass());
                JAXB_MAP.put(object.getClass().getCanonicalName(), jaxbContext);
                return jaxbContext;
            } catch (JAXBException e) {
                e.printStackTrace();
                return null;
            }
        }
    }
}

您可以在需要bean 类并在本地创建时调用getJAXBContext方法。JAXBContextMarshaller/Unmarshaller

于 2018-04-10T05:09:51.647 回答