java 如何使用 Jersey 缓存响应？

Question

提问by chiru

I am trying to develop restful API using Jersey.I have GET API's for a particular get operation my GET is taking same time from the same client. Is it possible to cache response? Any pointers is appreciated.

我正在尝试使用 Jersey 开发restful API。我有一个特定的获取操作的 GET API，我的 GET 正在从同一个客户端花费相同的时间。是否可以缓存响应？任何指针表示赞赏。

Thanks

谢谢

Answer 1

回答by TheWhiteRabbit

You can use CacheControl, eTag - follow below example code

您可以使用 CacheControl、eTag - 按照下面的示例代码

// 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();

Replace resourcewith your Resource instance.

替换resource为您的 Resource 实例。

Answer 2

回答by dur

Summary of solutions:

解决方案总结：

Requestas method parameter

Interface:

@Path("myentity")
public interface MyEntityResource

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

Implementation:

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();
    }
}

Disadvantages:

implementation detail Requestis exposed
return type Reponseis generic
missing grammar of return type in WADL
client proxywith unnecessary parameter Request

Requestas instance variable

Interface:

@Path("myentity")
public interface MyEntityResource

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

Implementation:

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();
    }
}

Disadvantages:

return type Reponseis generic
missing grammar of return type in WADL
dependency injection with @Contextis complicated, see https://stackoverflow.com/questions/33240443

ShallowEtagHeaderFilteras web filter

web.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>

Interface:

@Path("myentity")
public interface MyEntityResource

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

Implementation:

public class MyEntityResourceImpl implements MyEntityResource

    @Override
    public MyEntity getMyEntity() {

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

Disadvantages:

bad server performance, see JavaDoc
works only on uncommitted response
no support of weak ETag

Custom WriterInterceptoras JAX-RS Interceptor

Interceptor:

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);
        }
    }
}

See also: ServerCacheInterceptor(Resteasy)

Interface:

@Path("myentity")
public interface MyEntityResource

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

Implementation:

public class MyEntityResourceImpl implements MyEntityResource

    @Override
    public MyEntity getMyEntity() {

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

Disadvantages:

no predefined interceptor for Jersey available
bad server performance
no support of weak ETag
ugly workaround with WebApplicationException

请求作为方法参数

界面：

@Path("myentity")
public interface MyEntityResource

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

执行：

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();
    }
}

缺点：

实现细节Request公开
返回类型Reponse是通用的
WADL 中缺少返回类型的语法
带有不必要参数的客户端代理Request

请求作为实例变量

界面：

@Path("myentity")
public interface MyEntityResource

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

执行：

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();
    }
}

缺点：

返回类型Reponse是通用的
WADL 中缺少返回类型的语法
依赖注入@Context很复杂，见https://stackoverflow.com/questions/33240443

ShallowEtagHeaderFilter作为网络过滤器

网页.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>

界面：

@Path("myentity")
public interface MyEntityResource

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

执行：

public class MyEntityResourceImpl implements MyEntityResource

    @Override
    public MyEntity getMyEntity() {

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

缺点：

服务器性能不佳，请参阅JavaDoc
仅适用于未提交的响应
不支持弱 ETag

自定义WriterInterceptor作为JAX-RS 拦截器

拦截器：

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);
        }
    }
}

另请参阅：ServerCacheInterceptor（Resteasy）

界面：

@Path("myentity")
public interface MyEntityResource

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

执行：

public class MyEntityResourceImpl implements MyEntityResource

    @Override
    public MyEntity getMyEntity() {

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

缺点：

泽西岛没有可用的预定义拦截器
服务器性能不佳
不支持弱 ETag
丑陋的解决方法 WebApplicationException

Answer 3

回答by flash

You could use any caching mechanism applicable for standard java together with Jersey, like Ehcache.

您可以将适用于标准 java 的任何缓存机制与 Jersey 一起使用，例如Ehcache。

You only have to pay attention to verify that your data in the backend hasn't changed.

你只需要注意验证你在后端的数据没有改变。

Here is simple example with Ehcache:

这是一个简单的例子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();
}

Answer 4

回答by Andrey Lebedenko

Recently I've been solving the similar (if not the same) problem. As a side result of it the following library emerged: https://bitbucket.org/Andrey-Lebedenko/caching-filter

最近我一直在解决类似（如果不一样）的问题。作为它的附带结果，出现了以下库：https: //bitbucket.org/Andrey-Lebedenko/caching-filter

The way it can be used is like below:

它的使用方式如下：

@GET
@Produces(MediaType.APPLICATION_JSON)
@Path("/cached")
@ResponseCachedByFilter(10000)
public Object getCached() {
    return dao.get();
}

Hope it helps.

希望能帮助到你。

java 如何使用 Jersey 缓存响应？

提问by chiru

回答by TheWhiteRabbit

回答by dur

回答by flash

回答by Andrey Lebedenko

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java 如何使用 Jersey 缓存响应？

提问by chiru

回答by TheWhiteRabbit

回答by dur

回答by flash

回答by Andrey Lebedenko

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