Kotlin/Dropwizard 中的子资源定位器

Question

我正在尝试使用 Kotlin 1.0.3 在 Dropwizard 1.0 中实现具有子资源的资源。我有一个示例资源：

package net.reznik.stackoverflow.resources

import javax.ws.rs.Consumes
import javax.ws.rs.Path
import javax.ws.rs.PathParam
import javax.ws.rs.Produces
import javax.ws.rs.core.MediaType

@Path("/test")
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
class TestResource {

    @Path("/{foo}/")
    fun subresource(@PathParam("foo") foo: String): Any {
        return TestSubResource()
    }
}

还有一个子资源：

package net.reznik.stackoverflow.resources

import javax.ws.rs.POST
import javax.ws.rs.Path
import javax.ws.rs.core.MediaType
import javax.ws.rs.core.Response

class TestSubResource {

    @POST
    @Path("/bar")
    fun bar(request: String): Response {
        return Response.ok("entity received: $request", MediaType.TEXT_PLAIN_TYPE).build()
    }
}

如果我将子资源函数的返回类型从Any 更改为TestSubResource，那么一切都会按预期工作。我想使用Any 作为返回类型，这样我就可以根据{foo} 的值返回不同的子资源。

当使用Any 时，dropwizard 会在启动时以较长的堆栈跟踪崩溃...

WARN  [2016-08-31 22:01:32,454] /: unavailable
! java.lang.NullPointerException: null
! at io.dropwizard.jersey.DropwizardResourceConfig$EndpointLogger.populate(DropwizardResourceConfig.java:173)
! at io.dropwizard.jersey.DropwizardResourceConfig$EndpointLogger.populate(DropwizardResourceConfig.java:164)
! at io.dropwizard.jersey.DropwizardResourceConfig$EndpointLogger.populate(DropwizardResourceConfig.java:189)
! at io.dropwizard.jersey.DropwizardResourceConfig$EndpointLogger.populate(DropwizardResourceConfig.java:164)
! at io.dropwizard.jersey.DropwizardResourceConfig$EndpointLogger.populate(DropwizardResourceConfig.java:159)
! at io.dropwizard.jersey.DropwizardResourceConfig.getEndpointsInfo(DropwizardResourceConfig.java:130)
! at io.dropwizard.jersey.DropwizardResourceConfig.logComponents(DropwizardResourceConfig.java:80)
! at io.dropwizard.jersey.DropwizardResourceConfig$ComponentLoggingListener.onEvent(DropwizardResourceConfig.java:245)
! at org.glassfish.jersey.server.internal.monitoring.CompositeApplicationEventListener.onEvent(CompositeApplicationEventListener.java:74)
! at org.glassfish.jersey.server.ApplicationHandler.initialize(ApplicationHandler.java:629)
! at org.glassfish.jersey.server.ApplicationHandler.access$500(ApplicationHandler.java:184)
! at org.glassfish.jersey.server.ApplicationHandler$3.call(ApplicationHandler.java:350)
! at org.glassfish.jersey.server.ApplicationHandler$3.call(ApplicationHandler.java:347)
! at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
! at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
! at org.glassfish.jersey.internal.Errors.processWithException(Errors.java:255)
! at org.glassfish.jersey.server.ApplicationHandler.<init>(ApplicationHandler.java:347)
! at org.glassfish.jersey.servlet.WebComponent.<init>(WebComponent.java:392)
! at org.glassfish.jersey.servlet.ServletContainer.init(ServletContainer.java:177)
! at org.glassfish.jersey.servlet.ServletContainer.init(ServletContainer.java:369)
! at javax.servlet.GenericServlet.init(GenericServlet.java:244)
! at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:640)
! at org.eclipse.jetty.servlet.ServletHolder.initialize(ServletHolder.java:419)
! at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:875)
! at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:349)
! at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:772)
! at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:262)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
! at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
! at com.codahale.metrics.jetty9.InstrumentedHandler.doStart(InstrumentedHandler.java:103)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
! at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
! at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
! at org.eclipse.jetty.server.handler.gzip.GzipHandler.doStart(GzipHandler.java:231)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
! at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
! at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
! at org.eclipse.jetty.server.handler.StatisticsHandler.doStart(StatisticsHandler.java:252)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
! at org.eclipse.jetty.server.Server.start(Server.java:411)
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
! at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
! at org.eclipse.jetty.server.Server.doStart(Server.java:378)
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
! at io.dropwizard.cli.ServerCommand.run(ServerCommand.java:53)
! at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:44)
! at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:85)
! at io.dropwizard.cli.Cli.run(Cli.java:75)
! at io.dropwizard.Application.run(Application.java:79)

有没有办法使用 kotlin/dropwizard 实现子资源定位器，以便我可以根据我自己的自定义逻辑动态返回多个子资源之一 - 即，使用返回类型 Any？

Answer 1

当 Jersey 使用多态资源返回的类型也可能是资源时，它会在请求期间在运行时解析此子资源。 DropWizard 几乎按原样使用 Jersey，因此将支持此用例。

但是，DropWizard 有一个功能可以记录正在生成的路由绑定的输出，它会输出它在 Servlet 初始化期间确定的资源配置。而且这段代码有一个错误。我在这里报告了确切的错误：

https://github.com/dropwizard/dropwizard/issues/1716

我没有看到一个简单的解决方法，例如关闭此日志记录调用或取消注册事件。看来需要为 DropWizard 打补丁。

更新：此问题已通过拉取请求 https://github.com/dropwizard/dropwizard/pull/1718 解决，如果您使用该合并到 master 跟踪下一个版本，它将包含此修复。