如何緩存Jersey的響應？

10

您可以使用CacheControl，ETAG - 按照下面的示例代碼

// In your jersey method 
    final EntityTag eTag = new EntityTag(resource.getId() + "_" + 
    resource.getLastModified().getTime()); 
    final CacheControl cacheControl = new CacheControl(); 
    cacheControl.setMaxAge(-1); 

    ResponseBuilder builder = request.evaluatePreconditions(
     resource.getLastModified(), eTag); 

    // the resoruce's information was modified, return it 
    if (builder == null) { 
     builder = Response.ok(resource); 
    } 

    // the resource's information was not modified, return a 304 

    return builder.cacheControl(cacheControl).lastModified(
     resource.getLastModified()).tag(eTag).build();

與資源實例替換resource。

來源

2013-02-26 11:32:01 TheWhiteRabbit

+0

ü介意解釋爲什麼ü禁用緩存控制（無緩存）？它就像說：沒有緩存可能，但看看這裏我有一個無用的Etag和Last-Modified頭。 – Orri 2013-11-12 17:50:05

+2

這是說，它的永久緩存，但服務器可以說資源是否被修改基於電子標籤，因此客戶端/瀏覽器可以使用它從緩存 – TheWhiteRabbit 2013-11-13 09:18:12

3

你可以與新澤西一起使用適用於標準的java任何緩存機制，像Ehcache。

您只需要注意驗證後端數據沒有變化。

下面是簡單的例子與Ehcache：

@GET 
@Path("{id}") 
public List<Data> getData(@PathParam("id") Long id) { 
    Element element = CacheManager.getInstance().getCache("test").get(id); 
    if(element == null) { 
     Data value = fetchElementFromBackend(id); 
     CacheManager.getInstance().getCache("test").put(new Element(id, value)); 
     return value; 
    } 

    return element.getObjectValue(); 
}

來源

2013-02-26 11:31:51 flash

5

解決方案的概要：

Request作爲方法參數

接口：

@Path("myentity") 
public interface MyEntityResource 

    @GET 
    @Produces(MediaType.APPLICATION_JSON) 
    public Response getMyEntity(@Context final Request request); 
}

實現：

public class MyEntityResourceImpl implements MyEntityResource 

    @Override 
    public Response getMyEntity(final Request request) { 

     final MyEntity myEntity = ... // load entity 
     final String eTagValue = ... // calclutate value of ETag 

     final EntityTag eTag = new EntityTag(eTagValue); 

     ResponseBuilder responseBuilder = request.evaluatePreconditions(eTag); 

     if (responseBuilder == null) { 
      return Response.ok(user).tag(eTag).build(); 
     } 

     return responseBuilder.build(); 
    } 
}

缺點：

實現細節Request暴露
返回類型Reponse是通用
缺少返回類型的語法在WADL
client proxy不必要參數Request

Request作爲實例變量

接口：

@Path("myentity") 
public interface MyEntityResource 

    @GET 
    @Produces(MediaType.APPLICATION_JSON) 
    public Response getMyEntity(); 
}

實現：

public class MyEntityResourceImpl implements MyEntityResource 

    @Context 
    private Request request 

    @Override 
    public Response getMyEntity() { 

     final MyEntity myEntity = ... // load entity 
     final String eTagValue = ... // calclutate value of ETag 

     final EntityTag eTag = new EntityTag(eTagValue); 

     ResponseBuilder responseBuilder = request.evaluatePreconditions(eTag); 

     if (responseBuilder == null) { 
      return Response.ok(user).tag(eTag).build(); 
     } 

     return responseBuilder.build(); 
    } 
}

缺點：

返回類型Reponse是通用
缺少返回類型的語法WADL
依賴注入@Context是複雜的，看到https://stackoverflow.com/questions/33240443

ShallowEtagHeaderFilter如Web過濾

網絡。XML：

<filter> 
    <filter-name>etagFilter</filter-name> 
    <filter-class>org.springframework.web.filter.ShallowEtagHeaderFilter</filter-class> 
</filter> 
<filter-mapping> 
    <filter-name>etagFilter</filter-name> 
    <url-pattern>/api/*</url-pattern> 
</filter-mapping>

接口：

@Path("myentity") 
public interface MyEntityResource 

    @GET 
    @Produces(MediaType.APPLICATION_JSON) 
    public MyEntity getMyEntity(); 
}

實現：

public class MyEntityResourceImpl implements MyEntityResource 

    @Override 
    public MyEntity getMyEntity() { 

     final MyEntity myEntity = ... // load entity 
     return myEntity; 
    } 
}

缺點：

壞服務器的性能，看看JavaDoc
只有在提交響應
作品
不支持的weak ETag

定製WriterInterceptor爲JAX-RS Interceptor

攔截：

public class CustomInterceptor implements WriterInterceptor { 

    @Context 
    private Request request; 

    @Override 
    public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException { 

     OutputStream old = context.getOutputStream(); 

     ByteArrayOutputStream buffer = new ByteArrayOutputStream(); 

     try { 

      context.setOutputStream(buffer); 
      context.proceed(); 

      byte[] entity = buffer.toByteArray(); 

      String etag = ... // calclutate value of ETag 
      context.getHeaders().putSingle(HttpHeaders.ETAG, etag); 

      ResponseBuilder responseBuilder = request.evaluatePreconditions(eTag); 

      if (responseBuilder == null) { 
       throw new WebApplicationException(responseBuilder.status(Response.Status.NOT_MODIFIED).header(HttpHeaders.ETAG, etag).build()); 
      } 

      old.write(entity); 

     } finally { 
      context.setOutputStream(old); 
     } 
    } 
}

另請參見：ServerCacheInterceptor（RestEasy的）

接口：

@Path("myentity") 
public interface MyEntityResource 

    @GET 
    @Produces(MediaType.APPLICATION_JSON) 
    public MyEntity getMyEntity(); 
}

實現：

public class MyEntityResourceImpl implements MyEntityResource 

    @Override 
    public MyEntity getMyEntity() { 

     final MyEntity myEntity = ... // load entity 
     return myEntity; 
    } 
}

缺點：

沒有預定義的攔截器澤西可用
壞服務器性能
不支持的weak ETag
醜陋的解決方法與WebApplicationException

來源

2016-01-06 14:14:59 dur

如何緩存Jersey的響應？

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