Jonathan Lalou's blog

Archive for June, 2011

How to access a non-acccessible field (either protected, package-protected or private) of an object in Java?

For instance, you would like to access the field threads of ThreadGroup:

ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
final Field privateThreadsField;
privateThreadsField = ThreadGroup.class.getDeclaredField("threads");
privateThreadsField.setAccessible(true);
threads = (Thread[]) privateThreadsField.get(threadGroup);

Case

After rooting my Nexus S, I tried to flash the ROM, in order to replace the genuine GingerBread with a CyanoGen ehanced version. This worked pretty well, but for a amazing reason I do not know, I missed the so-called “GApps”: GMail, GMaps, etc., this way a Nexus S (or any other Android-driven mobile device) losing any interest. Then, it was the worst catastrophic epiphenomenon I might fear: the Nexus was “bricked”. Indeed, the splash screen, with the Android robot on a skate, did not stop from looping…

Brick, Block and Pitfall

I tried to restore CyanoGen, wipe the memory, etc., but nothing efficient. At last I decided to restore a genuine Gingerbread version.
Here is the puzzling block that stands on the road: a Nexus S does not contain an actual (I mean physical) SD memory card. The “virtual” SD card must be mounted via ADB. But ADB does not recognize the device, since the Nexus is “bricked”. The only access to the Nexus appears to be FastBoot… which does not recognize the /sdcard folder. And the circle is complete.

As you understand, the key is to be able to mount /sdcard, which is sufficient to copy a ROM, and then apply it as a regular update.

Fix

Here we assume you have a minimal knownledge on how to use ADB and FastBoot:

• Download recovery-clockwork-3.0.2.4-crespo.img
• Download GingerBread original ROM: da8206299fe6.signed-soju-ota-121341.da820629.zip
• Switch on your Nexus in recovery mode (sound up and on/off buttons at the same time)
• Select “recovery“
• Connect it to your PC
• On the PC: fastboot boot ~/recovery-clockwork-3.0.2.4-crespo.img
• Your phone reboots with a yellow on black console.
  • Select “mounts and storage” > “mount usb storage”
• Now your PC detects the phone as a regular mass storage device.
  • Copy GingerBread ROM to /sdcard folder.
  • Rename it as update.zip (optionnal, easier for the next step)
• On the PC: fastboot boot ~/recovery-clockwork-3.0.2.4-crespo.img
• On the phone,
  • select the option “apply update“
  • select update.zip
• Restart the phone
• If the phone freezes a long time, shut it down and switch it on again
• Now the regular Nexus splash screen should be OK

Case

Under WebLogic, I deploy RMI services:

    <bean id="fakeRmiServer" class="org.springframework.remoting.rmi.JndiRmiServiceExporter">
        <property name="service" ref="fakeInterfaceImpl" />
        <property name="serviceInterface" value="lalou.jonathan.FakeInterface" />
        <property name="jndiName" value="fakeRmiServer" />
    </bean>
    <bean id="fakeInterfaceImpl" class="lalou.jonathan.FakeInterfaceImpl" />

The WAR is hosted by a WebLogic 10.3.3 server (this point does not matter).

I retrieve the RMI services on client side, with this Spring config:

    <bean id="fakeServiceClient" class="org.springframework.remoting.rmi.JndiRmiProxyFactoryBean">
        <property name="jndiName" value="fakeRmiServer"/>
        <property name="jndiEnvironment">
            <props>
                <prop key="java.naming.factory.initial">weblogic.jndi.WLInitialContextFactory</prop>
                <prop key="java.naming.provider.url">t3://localhost:7003</prop>
            </props>
        </property>
        <property name="serviceInterface" value="lalou.jonathan.FakeInterface"/>
    </bean>

On launching the client side, I get this error:

java.lang.ClassCastException: Cannot narrow remote object ClusterableRemoteRef(-2462835584319760815S:123.123.123.123:[7003,7003,-1,-1,-1,-1,-1]:JonathanApplication:JonathanAdminServer [-2462835584319760815S:123.123.123.123:[7003,7003,-1,-1,-1,-1,-1]:JonathanApplication:JonathanAdminServer/375])/375 to lalou.jonathan.FakeInterface

Complete Stacktrace

java.lang.ClassCastException: Cannot narrow remote object ClusterableRemoteRef(-2462835584319760815S:123.123.123.123:[7003,7003,-1,-1,-1,-1,-1]:JonathanApplication:JonathanAdminServer [-2462835584319760815S:123.123.123.123:[7003,7003,-1,-1,-1,-1,-1]:JonathanApplication:JonathanAdminServer/375])/375 to lalou.jonathan.FakeInterface

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'fakeServiceClient' defined in class path resource [lalou/jonathan/java/webservices/jonathan-services.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [lalou.jonathan.java.webservices.FakeServiceWSServer]: Constructor threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'fakeServiceClient' defined in class path resource [lalou/jonathan/java/webservices/jonathan-rmi-client-spring.xml]: Invocation of init method failed; nested exception is org.springframework.remoting.RemoteLookupFailureException: Could not narrow RMI stub to service interface [lalou.jonathan.FakeInterface]; nested exception is java.lang.ClassCastException: Cannot narrow remote object ClusterableRemoteRef(-2462835584319760815S:123.123.123.123:[7003,7003,-1,-1,-1,-1,-1]:JonathanApplication:JonathanAdminServer [-2462835584319760815S:123.123.123.123:[7003,7003,-1,-1,-1,-1,-1]:JonathanApplication:JonathanAdminServer/375])/375 to lalou.jonathan.FakeInterface
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:883)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:839)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:440)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
        at java.security.AccessController.doPrivileged(Native Method)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
        at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:221)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:429)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:729)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:381)
        at org.apache.cxf.transport.servlet.CXFServlet.loadAdditionalConfig(CXFServlet.java:171)
        at org.apache.cxf.transport.servlet.CXFServlet.updateContext(CXFServlet.java:139)
        at org.apache.cxf.transport.servlet.CXFServlet.loadSpringBus(CXFServlet.java:101)
        at org.apache.cxf.transport.servlet.CXFServlet.loadBus(CXFServlet.java:70)
        at org.apache.cxf.transport.servlet.AbstractCXFServlet.init(AbstractCXFServlet.java:78)
        at (...)
        at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:440)
        at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:263)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:736)
        at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
        at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1282)
        at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:518)
        at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:499)
        at org.mortbay.jetty.plugin.Jetty6PluginWebAppContext.doStart(Jetty6PluginWebAppContext.java:115)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152)
        at org.mortbay.jetty.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:156)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:152)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
        at org.mortbay.jetty.Server.doStart(Server.java:224)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.plugin.Jetty6PluginServer.start(Jetty6PluginServer.java:132)
        at org.mortbay.jetty.plugin.AbstractJettyMojo.startJetty(AbstractJettyMojo.java:454)
        at org.mortbay.jetty.plugin.AbstractJettyMojo.execute(AbstractJettyMojo.java:396)
        at org.mortbay.jetty.plugin.Jetty6RunWarExploded.execute(Jetty6RunWarExploded.java:170)
        at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
        at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
        at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
        at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:375)

Fix

Indeed, this issue appeared with Spring 2.5.4, and was fixed with 2.5.6 release. I let you guess which version I was using…
(cf. Spring 2.5.6 Changelog: * JndiRmiClientInterceptor skips narrowing for RmiInvocationHandler stubs (fixing a regression in 2.5.4)
Therefore, to fix this issue you have to upgrade your Spring version to 2.5.6.

Case

Migrating a cache from EhCache to Tangosol / Oracle Coherence, I got the following error when the cache started to be filled:

com.tangosol.io.lh.LHIOException:C:\DOCUME~1\JonathanLalou\LOCALS~1\Temp\jonathanLalouCache.store, Primary file, Reading, Group 880, Frame 880: End of file reached

Quick Fix

I could not fix the issue itself. The documentation is not abundant on the subject. I never enjoyed working on closed source libraries. Anyway, a quick fix consists in replacing the LH store with a Berkeley DB store, ie replacing:

<lh-file-manager><file-name>{cache-name}.store</file-name></lh-file-manager>

with some kind of:

<bdb-store-manager></bdb-store-manager>