java - CacheLoader 多次加载相同的键

Question

我的 cacheIterator 中有重复的键。

我正在调用一个使用 SOAP 的 Web 服务来为保险公司的保单评级。我正在尝试使用 Cachebuilder/loader 将 DTO 存储为键并将服务的响应存储为值。根据我的研究，.get 和 .getUnchecked 方法将从缓存中获取一个值，如果它不存在，它将将该值加载到缓存中。这是一些代码:

public class CacheLoaderImpl
{
   private static CacheLoaderImpl instance = null;
   private static LoadingCache<PolicyDTO, RatingServiceObjectsResponse> responses;

   protected CacheLoaderImpl()
   {
      responses = CacheBuilder.newBuilder()
            .expireAfterWrite(10, TimeUnit.MINUTES)
            .build(
                new CacheLoader<PolicyDTO, RatingServiceObjectsResponse>() {
                  public RatingServiceObjectsResponse load(PolicyDTO key)
                        throws Exception
                  {
                      return getResponse(key);
                  }
                });
   }

   public static CacheLoaderImpl getIntance()
   {
      if(instance == null)
      {
         instance = new CacheLoaderImpl();
      }

      return instance;
   }

   public LoadingCache<PolicyDTO, RatingServiceObjectsResponse> getResponses()
   {
      return responses;
   }

   public RatingServiceObjectsResponse getResponse(PolicyDTO key) throws ExecutionException
   {
     RatingServiceObjectsResponse response = new RatingServiceObjectsResponse();
     try
     {
         response = new CGIRatabaseServiceImpl().getCoverages(key);
     }
     catch (RemoteException e)
     {
        e.printStackTrace();
     }
     catch (IllegalArgumentException e)
     {
        e.printStackTrace();
     }
     return response;

   }

}

这就是我调用 get 方法的地方:

RatingServiceObjectsResponse response = CacheLoaderImpl.getIntance().getResponses().get(policy.toCoveragesCallDTO()); 

我假设它可能正在比较不同的内存地址，所以我重写了 toString 方法以将 DTO 对象转换为 JSON。检查缓存后，我可以看到键与比较工具完全相同。然而，它们仍然被存储并每次都调用该服务。我尝试覆盖 PolicyDTO 上的 equals 方法，但在调试时它从未命中。

我怎样才能让缓存加载器只加载不同键的值，并按照最初的意图提取现有值？

我想我只是不太清楚 cacheLoader 的实际工作原理。我感谢任何帮助或建议。

PolicyDTO 类:

public class PolicyDTO extends AbstractDto implements IPolicyDTO
{
   private ArrayList<ILineOfBusinessDTO> lobDTOs = new ArrayList<ILineOfBusinessDTO>();
   private String pcInd;
   private String ratingEffectiveDate;
   private String companyName;

   public String getPcInd()
   {
      return pcInd;
   }

   public void setPcInd(String pcInd)
   {
      this.pcInd = pcInd;
   }

   public String getRatingEffectiveDate()
   {
      return ratingEffectiveDate;
   }

   public void setRatingEffectiveDate(AdvancedDate ratingEffectiveDate)
   {
      if(ratingEffectiveDate != null)
      {
         this.ratingEffectiveDate = ratingEffectiveDate.toFormattedStringMMDDYYYY();
      }
      else
      {
         this.ratingEffectiveDate = new AdvancedDate().toFormattedStringMMDDYYYY();
      }
   }

   public String getCompanyName()
   {
      return companyName;
   }

   public void setCompanyName(String companyName)
   {
      this.companyName = companyName;
   }

  public DtoType getType()
   {
       return hasGetCoveragesCoverageDTO() ? DtoType.GET_COVERAGE_POLICY : DtoType.RATE_POLICY;
   }

   public boolean hasGetCoveragesCoverageDTO()
   {
       if(lobDTOs != null)
       {
           for(ILineOfBusinessDTO lineDTO : lobDTOs)
           {
               if(lineDTO.hasGetCoveragesCoverageDTO())
               {
                   return true;
               }
           }
       }

       return false;
   }

    @Override
    public void addLob(ILineOfBusinessDTO lob) {

        lobDTOs.add(lob);
    }

    @Override
    public Iterator<ILineOfBusinessDTO> getLobIterator() {

        return lobDTOs.iterator();
    }

    public ICoverageDTO findCoverage(String coverageID)
    {
        ICoverageDTO coverageDTO = null;

        for(ILineOfBusinessDTO lineDTO : lobDTOs)
        {
            coverageDTO = lineDTO.findCoverage(coverageID);

            if(coverageDTO != null)
            {
                return coverageDTO;
            }
        }

        return null;
    }
    @Override
    public String toString()
    {
       return JSONConversionUtility.convertPolicyDTO(this);
    }

    @Override
   public int hashCode()
   {
      final int prime = 31;
      int result = 1;
      result = prime * result
            + ((companyName == null) ? 0 : companyName.hashCode());
      result = prime * result + ((lobDTOs == null) ? 0 : lobDTOs.hashCode());
      result = prime * result + ((pcInd == null) ? 0 : pcInd.hashCode());
      result = prime
            * result
            + ((ratingEffectiveDate == null) ? 0 : ratingEffectiveDate
                  .hashCode());
      return result;
   }

    @Override 
   public boolean equals(Object object)
   {
      if(object instanceof PolicyDTO)
      {
         return object.toString().equals(this.toString());
      }
      return false;

   }
}

Answer 1

您的 PolicyDTO 类的 hashCode 与 equals 不一致 - 它违反了以下规则:

If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.

缓存使用 hashCode(很像 HashMap 类)，所以当它看到两个具有不同哈希码的键时，它会假定它们不相等。