如何禁用从控制器返回的对象上的弹簧销毁回调

Question

EDIT: This turned out to be something else in my configuration

Whenever I return an object with an inferable destruction method from a rest controller, the returned object gets closed, is it possible to disable this?

For example if I have an object like this:

public class MyObject implements AutoCloseable {

  // Some json
  private @JsonValue String foo = "hello world";

  public void close () throws Exception {
    System.out.println ("close()");
    new Throwable ("STACK TRACE").printStackTrace (System.out);
  }
}

And a controller like this:

@Controller
public class MyController {

  private Map<String, MyObject> objects = new HashMap<> ();

  @PostConstruct
  private void populate () {
    objects.put ("one", new MyObject ());
    objects.put ("two", new MyObject ());
  }

  @RequestMapping ("/hello/{id}")
  @ResponseBody
  public MyObject test (@PathVariable ("id") String id) {
    return objects.get (id);
  }
}

Spring will call MyObject.close() after it is returned from the controller method. This is clearly not a spring managed object and I'd like to disable closing it, syntactically at the controller method site, is that possible?

This is with Spring 3.2 and 4.0, from googling around I believe it doesn't happen in 3.1.

EDIT: Posting the stack trace, the final cleanup() method has a @PreDestroy annotation on it, but same thing happens if I implement AutoCloseable. Objects of SimpleDataset class are not managed by Spring.

java.lang.Throwable: STACK TRACE
    at edu.dfci.cccb.mev.dataset.domain.simple.SimpleDataset.cleanup(SimpleDataset.java:106)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:349)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeDestroyMethods(InitDestroyAnnotationBeanPostProcessor.java:314)
    at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeDestruction(InitDestroyAnnotationBeanPostProcessor.java:153)
    at org.springframework.beans.factory.support.DisposableBeanAdapter.destroy(DisposableBeanAdapter.java:238)
    at org.springframework.beans.factory.support.DisposableBeanAdapter.run(DisposableBeanAdapter.java:231)
    at org.springframework.web.context.request.AbstractRequestAttributes.executeRequestDestructionCallbacks(AbstractRequestAttributes.java:91)
    at org.springframework.web.context.request.AbstractRequestAttributes.requestCompleted(AbstractRequestAttributes.java:47)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:949)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:822)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:735)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:807)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:686)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:501)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:255)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
    at org.eclipse.jetty.server.Server.handle(Server.java:370)
    at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489)
    at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:949)
    at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1011)
    at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644)
    at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
    at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
    at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668)
    at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
    at java.lang.Thread.run(Thread.java:722)

Answer 1

When you have @ResponseBody annotated handler method, Spring uses a RequestResponseBodyMethodProcessor to handle the value returned.

This is done in ServletInvocableHandlerMethod#invokeAndHandler(..) which is implemented as such

public final void invokeAndHandle(ServletWebRequest webRequest,
        ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {

    Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);

    setResponseStatus(webRequest);

    if (returnValue == null) {
        if (isRequestNotModified(webRequest) || hasResponseStatus() || mavContainer.isRequestHandled()) {
            mavContainer.setRequestHandled(true);
            return;
        }
    }
    else if (StringUtils.hasText(this.responseReason)) {
        mavContainer.setRequestHandled(true);
        return;
    }

    mavContainer.setRequestHandled(false);

    try {
        this.returnValueHandlers.handleReturnValue(returnValue, getReturnValueType(returnValue), mavContainer, webRequest);
    }
    catch (Exception ex) {
        if (logger.isTraceEnabled()) {
            logger.trace(getReturnValueHandlingErrorMessage("Error handling return value", returnValue), ex);
        }
        throw ex;
    }
}

where

this.returnValueHandlers.handleReturnValue(returnValue, getReturnValueType(returnValue), mavContainer, webRequest);

delegates to the RequestResponseBodyMethodProcessor . Nothing in here calls close() on your return value.

What you are describing is not possible by default. You must have something else in your configuration.