Spring - Replacing the bean property values with new Property File values - java

I have a property file and using Spring property place holder, I set values to the Spring beans. Now, this property file may be modified during the run time. Is there a way to refresh the properties of the Spring beans with this newly modified property value? Especially, I have many singleton beans? How can I refresh them with the new values? Is there already a solution to this or should it be custom coded? If it doesn't already exist, can someone please give the best approach to achieve this? Thanks!
PS: My application is a batch application. I use Spring based Quartz configuration to schedule the batches.


I'll leave this in for reference, but the updated answer is below the divider:
Well the ConfigurableApplicationContext interface contains a refresh() method, which should be what you want, but the question is: how to access that method. Whichever way you do it, you'll start with a bean that has a dependency of type ConfigurableApplicationContext:
private ConfigurableApplicationContext context;
#Autowired
public void setContext(ConfigurableApplicationContext ctx){
this.context = ctx;
}
Now the two basic options I'd suggest would be to either
use the Task Execution Framework and let your bean watch the property resources regularly, refreshing the ApplicationContext when it finds changes or
expose the bean to JMX, allowing you to manually trigger the refresh.
Referring to comments: since it seems impossible to refresh the entire context, an alternative strategy would be to create a properties factory bean and inject that into all other beans.
public class PropertiesFactoryBean implements FactoryBean<Properties>{
public void setPropertiesResource(Resource propertiesResource){
this.propertiesResource = propertiesResource;
}
private Properties value=null;
long lastChange = -1L;
private Resource propertiesResource;
#Override
public Properties getObject() throws Exception{
synchronized(this){
long resourceModification = propertiesResource.lastModified();
if(resourceModification != lastChange){
Properties newProps = new Properties();
InputStream is = propertiesResource.getInputStream();
try{
newProps.load(is);
} catch(IOException e){
throw e;
} finally{
IOUtils.closeQuietly(is);
}
value=newProps;
lastChange= resourceModification;
}
}
// you might want to return a defensive copy here
return value;
}
#Override
public Class<?> getObjectType(){
return Properties.class;
}
#Override
public boolean isSingleton(){
return false;
}
}
You could inject this properties bean into all your other beans, however, you would have to be careful to always use prototype scope. This is particularly tricky inside singleton beans, a solution can be found here.
If you don't want to inject lookup methods all over the place, you could also inject a PropertyProvider bean like this:
public class PropertiesProvider implements ApplicationContextAware{
private String propertyBeanName;
private ApplicationContext applicationContext;
public void setPropertyBeanName(final String propertyBeanName){
this.propertyBeanName = propertyBeanName;
}
#Override
public void setApplicationContext(final ApplicationContext applicationContext) throws BeansException{
this.applicationContext = applicationContext;
}
public String getProperty(final String propertyName){
return ((Properties) applicationContext.getBean(propertyBeanName)).getProperty(propertyName);
}
}

Related

Java EE 7 Batch API : produce job scoped CDI Bean

I'm currently working on a Java EE 7 Batch API application, and I would like the lifecycle of one of my CDI Bean be related to the current job.
Actually I would like this bean to have a #JobScoped scope (but it doesn't exist in the API). Also I would like this bean to be injectable in any of my jobs class.
At first, I wanted to create my own #JobScoped scope, with a JobScopedContext, etc. But then I came with the idea that Batch API has the JobContext bean with a unique job id per bean.
So I wonder if I could manage the lifecycle of my job scoped bean with this JobContext.
For example, I would have my bean that I want to be job scoped :
#Alternative
public class JobScopedBean
{
private String m_value;
public String getValue()
{
return m_value;
}
public void setValue(String p_value)
{
m_value = p_value;
}
}
Then I would have the producer of this bean which will return the JobScopedBean associated to the current job (thanks to the JobContext which is unique per job)
public class ProducerJobScopedBean
{
#Inject
private JobContext m_jobContext;// this is the JobContext of Batch API
#Inject
private JobScopedManager m_manager;
#Produces
public JobScopedBean getObjectJobScoped() throws Exception
{
if (null == m_jobContext)
{
throw new Exception("Job Context not active");
}
return m_manager.get(m_jobContext.getExecutionId());
}
}
And the manager which holds the map of my JobScopedBean :
#ApplicationScoped
public class JobScopedManager
{
private final ConcurrentMap<Long, JobScopedBean> mapObjets = new ConcurrentHashMap<Long, JobScopedBean>();
public JobScopedBean get(final long jobId)
{
JobScopedBean returnObject = mapObjets.get(jobId);
if (null == returnObject)
{
final JobScopedBean ajout = new JobScopedBean();
returnObject = mapObjets.putIfAbsent(jobId, ajout);
if (null == returnObject)
{
returnObject = ajout;
}
}
return returnObject;
}
Of course, I will manage the destruction of the JobScopedBean at the end of each job (through a JobListener and a CDI Event).
Can you tell me if I'm wrong with this solution?
It looks correct to me but maybe I'm missing something?
May be there is a better way to handle this?
Thanks.

So it boils down to creating #Dependent scoped beans that are based on a job on creation. Works fine for beans with a lifespan shorter than the job, so for the standard scopes only #Dependent (#Request/#Session/#Converstion might be ok but do not apply here).
It will cause problems for other Scopes, especially #ApplicationScoped/#Singleton. If you inject the JobScopedBean into one of them. You might be (un)lucky to have an active Job when you need them the first time, but the beans will always be attached to that initial job (#Dependent scope beans are not pseudoscoped so will not create proxies to get the contextual instance)
If you want something like that, create a customscope.

DeltaSpike custom ConfigSource with CDI

I am trying to define a custom DeltaSpike ConfigSource. The custom config source will have the highest priority and check the database for the config parameter.
I have a ConfigParameter entity, that simply has a key and a value.
#Entity
#Cacheable
public class ConfigParameter ... {
private String key;
private String value;
}
I have a #Dependent DAO that finds all config parameters.
What I am trying to do now, is define a custom ConfigSource, that is able to get the config parameter from the database. Therefore, I want to inject my DAO in the ConfigSource. So basically something like
#ApplicationScoped
public class DatabaseConfigSource implements ConfigSource {
#Inject
private ConfigParameterDao configParameterDao;
....
}
However, when registering the ConfigSource via META-INF/services/org.apache.deltaspike.core.spi.config.ConfigSource, the class will be instantiated and CDI will not work.
Is there any way to get CDI working in this case?
Thanks in advance, if you need any further information, please let me know.

The main problem is, that the ConfigSource gets instantiated very early on when the BeanManager is not available yet. Even the JNDI lookup does not work at that point in time. Thus, I need to delay the injection/lookup.
What I did now, is add a static boolean to my config source, that I set manually. We have a InitializerService that makes sure that the system is setup properly. At the end of the initialization process, I call allowInitialization() in order to tell the config source, that the bean is injectable now. Next time the ConfigSource is asked, it will be able to inject the bean using BeanProvider.injectFields.
public class DatabaseConfigSource implements ConfigSource {
private static boolean allowInit;
#Inject
private ConfigParameterProvider configParameterProvider;
#Override
public int getOrdinal() {
return 500;
}
#Override
public String getPropertyValue(String key) {
initIfNecessary();
if (configParameterProvider == null) {
return null;
}
return configParameterProvider.getProperty(key);
}
public static void allowInitialization() {
allowInit = true;
}
private void initIfNecessary() {
if (allowInit) {
BeanProvider.injectFields(this);
}
}
}
I have a request-scoped bean that holds all my config variables for type-safe access.
#RequestScoped
public class Configuration {
#Inject
#ConfigProperty(name = "myProperty")
private String myProperty;
#Inject
#ConfigProperty(name = "myProperty2")
private String myProperty2;
....
}
When injecting the Configuration class in a different bean, each ConfigProperty will be resolved. Since my custom DatabaseConfigSource has the highest ordinal (500), it will be used for property resolution first. If the property is not found, it will delegate the resolution to the next ConfigSource.
For each ConfigProperty the getPropertyValue function from the DatabaseConfigSource is called. Since I do not want to retreive the parameters from the database for each config property, I moved the config property resolution to a request-scoped bean.
#RequestScoped
public class ConfigParameterProvider {
#Inject
private ConfigParameterDao configParameterDao;
private Map<String, String> configParameters = new HashMap<>();
#PostConstruct
public void init() {
List<ConfigParameter> configParams = configParameterDao.findAll();
configParameters = configParams.stream()
.collect(toMap(ConfigParameter::getId, ConfigParameter::getValue));
}
public String getProperty(String key) {
return configParameters.get(key);
}
}
I could sure change the request-scoped ConfigParameterProvider to ApplicationScoped. However, we have a multi-tenant setup and the parameters need to be resolved per request.
As you can see, this is a bit hacky, because we need to explicitly tell the ConfigSource, when it is allowed to be instantiated properly (inject the bean).
I would prefer a standarized solution from DeltaSpike for using CDI in a ConfigSource. If you have any idea on how to properly realise this, please let me know.

Even though this post has been answered already I'd like to suggest another possible solution for this problem.
I managed to load properties from my db service by creating an #Signleton #Startup EJB which extends the org.apache.deltaspike.core.impl.config.BaseConfigSource and injects my DAO as delegate which I then registered into the org.apache.deltaspike.core.api.config.ConfigResolver.
#Startup
#Singleton
public class DatabaseConfigSourceBean extends BaseConfigSource {
private static final Logger logger = LoggerFactory.getLogger(DatabaseConfigSourceBean.class);
private #Inject PropertyService delegateService;
#PostConstruct
public void onStartup() {
ConfigResolver.addConfigSources(Collections.singletonList(this));
logger.info("Registered the DatabaseConfigSourceBean in the ConfigSourceProvider ...");
}
#Override
public Map<String, String> getProperties() {
return delegateService.getProperties();
}
#Override
public String getPropertyValue(String key) {
return delegateService.getPropertyValue(key);
}
#Override
public String getConfigName() {
return DatabaseConfigSourceBean.class.getSimpleName();
}
#Override
public boolean isScannable() {
return true;
}
}
I know that creating an EJB for this purpose basically produces a way too big overhead, but I think it's a bit of a cleaner solution instead of handling this problem by some marker booleans with static accessors ...

DS is using the java se spi mechanism for this which is not CD'Injectable'. One solution would be to use the BeanProvider to get hold of your DatabaseConfigSource and delegate operations to it.

Is it possible to have Spring inject only already-initialized instances of a type? [duplicate]

I have several beans in my Spring context that have state, so I'd like to reset that state before/after unit tests.
My idea was to add a method to a helper class which just goes through all beans in the Spring context, checks for methods that are annotated with #Before or #After and invoke them.
How do I get a list of instantiated beans from the ApplicationContext?
Note: Solutions which simply iterate over all defined beans are useless because I have many lazy beans and some of them must not be instantiated because that would fail for some tests (i.e. I have a beans that need a java.sql.DataSource but the tests work because they don't need that bean).

For example:
public static List<Object> getInstantiatedSigletons(ApplicationContext ctx) {
List<Object> singletons = new ArrayList<Object>();
String[] all = ctx.getBeanDefinitionNames();
ConfigurableListableBeanFactory clbf = ((AbstractApplicationContext) ctx).getBeanFactory();
for (String name : all) {
Object s = clbf.getSingleton(name);
if (s != null)
singletons.add(s);
}
return singletons;
}

I had to improve it a little
#Resource
AbstractApplicationContext context;
#After
public void cleanup() {
resetAllMocks();
}
private void resetAllMocks() {
ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
for (String name : context.getBeanDefinitionNames()) {
Object bean = beanFactory.getSingleton(name);
if (Mockito.mockingDetails(bean).isMock()) {
Mockito.reset(bean);
}
}
}

I am not sure whether this will help you or not.
You need to create your own annotation eg. MyAnnot.
And place that annotation on the class which you want to get.
And then using following code you might get the instantiated bean.
ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false);
scanner.addIncludeFilter(new AnnotationTypeFilter(MyAnnot.class));
for (BeanDefinition beanDefinition : scanner.findCandidateComponents("com.xxx.yyy")){
System.out.println(beanDefinition.getBeanClassName());
}
This way you can get all the beans having your custom annotation.

applicationContext.getBeanDefinitionNames() does not show the beans which are registered without BeanDefinition instance.
package io.velu.core;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
#Configuration
#ComponentScan
public class Core {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Core.class);
String[] singletonNames = context.getDefaultListableBeanFactory().getSingletonNames();
for (String singleton : singletonNames) {
System.out.println(singleton);
}
}
}
Console Output
environment
systemProperties
systemEnvironment
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
messageSource
applicationEventMulticaster
lifecycleProcessor
As you can see in the output, environment, systemProperties, systemEnvironment beans will not be shown using context.getBeanDefinitionNames() method.
Spring Boot
For spring boot web applications, all the beans can be listed using the below endpoint.
#RestController
#RequestMapping("/list")
class ExportController {
#Autowired
private ApplicationContext applicationContext;
#GetMapping("/beans")
#ResponseStatus(value = HttpStatus.OK)
String[] registeredBeans() {
return printBeans();
}
private String[] printBeans() {
AutowireCapableBeanFactory autowireCapableBeanFactory = applicationContext.getAutowireCapableBeanFactory();
if (autowireCapableBeanFactory instanceof SingletonBeanRegistry) {
String[] singletonNames = ((SingletonBeanRegistry) autowireCapableBeanFactory).getSingletonNames();
for (String singleton : singletonNames) {
System.out.println(singleton);
}
return singletonNames;
}
return null;
}
}
[
"autoConfigurationReport",
"springApplicationArguments",
"springBootBanner",
"springBootLoggingSystem",
"environment",
"systemProperties",
"systemEnvironment",
"org.springframework.context.annotation.internalConfigurationAnnotationProcessor",
"org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory",
"org.springframework.boot.autoconfigure.condition.BeanTypeRegistry",
"org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry",
"propertySourcesPlaceholderConfigurer",
"org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.store",
"preserveErrorControllerTargetClassPostProcessor",
"org.springframework.context.annotation.internalAutowiredAnnotationProcessor",
"org.springframework.context.annotation.internalRequiredAnnotationProcessor",
"org.springframework.context.annotation.internalCommonAnnotationProcessor",
"org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor",
"org.springframework.scheduling.annotation.ProxyAsyncConfiguration",
"org.springframework.context.annotation.internalAsyncAnnotationProcessor",
"methodValidationPostProcessor",
"embeddedServletContainerCustomizerBeanPostProcessor",
"errorPageRegistrarBeanPostProcessor",
"messageSource",
"applicationEventMulticaster",
"org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration$EmbeddedTomcat",
"tomcatEmbeddedServletContainerFactory",
"org.springframework.boot.autoconfigure.websocket.WebSocketAutoConfiguration$TomcatWebSocketConfiguration",
"websocketContainerCustomizer",
"spring.http.encoding-org.springframework.boot.autoconfigure.web.HttpEncodingProperties",
"org.springframework.boot.autoconfigure.web.HttpEncodingAutoConfiguration",
"localeCharsetMappingsCustomizer",
"org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration",
"serverProperties",
"duplicateServerPropertiesDetector",
"spring.resources-org.springframework.boot.autoconfigure.web.ResourceProperties",
"org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$DefaultErrorViewResolverConfiguration",
"conventionErrorViewResolver",
"org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration",
"errorPageCustomizer",
"servletContext",
"contextParameters",
"contextAttributes",
"spring.mvc-org.springframework.boot.autoconfigure.web.WebMvcProperties",
"spring.http.multipart-org.springframework.boot.autoconfigure.web.MultipartProperties",
"org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration",
"multipartConfigElement",
"org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration",
"org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletConfiguration",
"dispatcherServlet",
"dispatcherServletRegistration",
"requestContextFilter",
"org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration",
"hiddenHttpMethodFilter",
"httpPutFormContentFilter",
"characterEncodingFilter",
"org.springframework.context.event.internalEventListenerProcessor",
"org.springframework.context.event.internalEventListenerFactory",
"reportGeneratorApplication",
"exportController",
"exportService",
"org.springframework.boot.autoconfigure.AutoConfigurationPackages",
"org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration",
"org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$Jackson2ObjectMapperBuilderCustomizerConfiguration",
"spring.jackson-org.springframework.boot.autoconfigure.jackson.JacksonProperties",
"standardJacksonObjectMapperBuilderCustomizer",
"org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$JacksonObjectMapperBuilderConfiguration",
"org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration",
"jsonComponentModule",
"jacksonObjectMapperBuilder",
"org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$JacksonObjectMapperConfiguration",
"jacksonObjectMapper",
"org.springframework.boot.autoconfigure.websocket.WebSocketAutoConfiguration",
"org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration",
"org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration",
"org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration",
"defaultValidator",
"org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration",
"error",
"beanNameViewResolver",
"errorAttributes",
"basicErrorController",
"org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$EnableWebMvcConfiguration",
"org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter",
"mvcContentNegotiationManager",
"org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration$StringHttpMessageConverterConfiguration",
"stringHttpMessageConverter",
"org.springframework.boot.autoconfigure.web.JacksonHttpMessageConvertersConfiguration$MappingJackson2HttpMessageConverterConfiguration",
"mappingJackson2HttpMessageConverter",
"org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration",
"messageConverters",
"mvcConversionService",
"mvcValidator",
"requestMappingHandlerAdapter",
"mvcResourceUrlProvider",
"requestMappingHandlerMapping",
"mvcPathMatcher",
"mvcUrlPathHelper",
"viewControllerHandlerMapping",
"beanNameHandlerMapping",
"resourceHandlerMapping",
"defaultServletHandlerMapping",
"mvcUriComponentsContributor",
"httpRequestHandlerAdapter",
"simpleControllerHandlerAdapter",
"handlerExceptionResolver",
"mvcViewResolver",
"org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter$FaviconConfiguration",
"faviconRequestHandler",
"faviconHandlerMapping",
"defaultViewResolver",
"viewResolver",
"welcomePageHandlerMapping",
"org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration",
"objectNamingStrategy",
"mbeanServer",
"mbeanExporter",
"org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration",
"springApplicationAdminRegistrar",
"org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration",
"org.springframework.boot.autoconfigure.web.JacksonHttpMessageConvertersConfiguration",
"spring.info-org.springframework.boot.autoconfigure.info.ProjectInfoProperties",
"org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration",
"multipartResolver",
"org.springframework.boot.autoconfigure.web.WebClientAutoConfiguration$RestTemplateConfiguration",
"restTemplateBuilder",
"org.springframework.boot.autoconfigure.web.WebClientAutoConfiguration",
"spring.devtools-org.springframework.boot.devtools.autoconfigure.DevToolsProperties",
"org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration$RestartConfiguration",
"fileSystemWatcherFactory",
"classPathRestartStrategy",
"classPathFileSystemWatcher",
"hateoasObjenesisCacheDisabler",
"org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration$LiveReloadConfiguration$LiveReloadServerConfiguration",
"org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration$LiveReloadConfiguration",
"optionalLiveReloadServer",
"org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration",
"lifecycleProcessor"
]

I've created a gist ApplicationContextAwareTestBase.
This helper class does two things:
It sets all internal fields to null. This allows Java to free memory that isn't used anymore. It's less useful with Spring (the Spring context still keeps references to all the beans), though.
It tries to find all methods annotated with #After in all beans in the context and invokes them after the test.
That way, you can easily reset state of your singletons / mocks without having to destroy / refresh the context.
Example: You have a mock DAO:
public void MockDao implements IDao {
private Map<Long, Foo> database = Maps.newHashMap();
#Override
public Foo byId( Long id ) { return database.get( id ) );
#Override
public void save( Foo foo ) { database.put( foo.getId(), foo ); }
#After
public void reset() { database.clear(); }
}
The annotation will make sure reset() will be called after each unit test to clean up the internal state.

Using the previous answers, I've updated this to use Java 8 Streams API:
#Inject
private ApplicationContext applicationContext;
#Before
public void resetMocks() {
ConfigurableListableBeanFactory beanFactory = ((AbstractApplicationContext) applicationContext).getBeanFactory();
Stream.of(applicationContext.getBeanDefinitionNames())
.map(n -> beanFactory.getSingleton(n))
// My ConfigurableListableBeanFactory isn't compiled for 1.8 so can't use method reference. If yours is, you can say
// .map(ConfigurableListableBeanFactory::getSingleton)
.filter(b -> Mockito.mockingDetails(b).isMock())
.forEach(Mockito::reset);
}

how to reattach singleton Spring beans upon deserialization

I want to reinject singleton-scoped dependencies into prototype Spring beans, after they have been deserialized.
Say I've got a Process bean, which depends on a Repository bean. The Repository bean is a scoped as a singleton, but the Process bean is prototype-scoped. Periodically I serialize the Process, and then later deserialize it.
class Process {
private Repository repository;
// getters, setters, etc.
}
I don't want to serialize and deserialize the Repository. Nor do I want to put "transient" on the member variable that holds a reference to it in Process, nor a reference to some kind of proxy, or anything other than a plain old member variable declared as a Repository.
What I think I want is for the Process to have its dependency filled with a serializable proxy that points (with a transient reference) to the Repository, and, upon deserialization, can find the Repository again. How could I customize Spring to do that?
I figure I could use a proxy to hold the dependency references, much like . I wish I could use that exact technique. But the proxy I've seen Spring generate isn't serializable, and the docs say that if I use it with a singleton bean, I'll get an exception.
I could use a custom scope, perhaps, on the singleton beans, that would always supply a proxy when asked for a custom-scoped bean. Is that a good idea? Other ideas?

I used this instead, without any proxy:
public class Process implements HttpSessionActivationListener {
...
#Override
public void sessionDidActivate(HttpSessionEvent e) {
ServletContext sc = e.getSession().getServletContext();
WebApplicationContext newContext = WebApplicationContextUtils
.getRequiredWebApplicationContext(sc);
newContext.getAutowireCapableBeanFactory().configureBean(this, beanName);
}
}
The example is for a web environment when the application server serializes the session, but it should work for any ApplicationContext.

Spring provides a solution for this problem.
Take a look at the spring documentation http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/aop.html#aop-atconfigurable.
7.8.1 Using AspectJ to dependency inject domain objects with Spring
...
The support is intended to be used for objects created outside
of the control of any container. Domain objects often fall into
this category because they are often created programmatically
using the new operator, or by an ORM tool as a result of a database query.
The trick is to use load time weaving. Just start the jvm with -javaagent:path/to/org.springframework.instrument-{version}.jar. This agent will recognize every object that is instantiated and if it is annotated with #Configurable it will configure (inject #Autowired or #Resource dependencies) that object.
Just change the Process class to
#Configurable
class Process {
#Autowired
private transient Repository repository;
// getters, setters, etc.
}
Whenever you create a new instance
Process process = new Process();
spring will automatically inject the dependencies.
This also works if the Process object is deserialized.

How about added using aspects to add an injection step when you deserialize the object?
You would need AspectJ or similar for this. It would work very similarly to the #Configurable function in Spring.
e.g. add some advice around the a "private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException" method
This article may also help: http://java.sun.com/developer/technicalArticles/Programming/serialization/

I think the idea of serializing a bean and then forcing a reinjection of dependencies is not the best architecture.
How about having some sort of ProcessWrapper bean instead which could be a singleton. It would be injected with the Repository and either manages the deserialization of the Process or has a setter for it. When a new Process is set in the wrapper, it would call setRepository() on the Process. The beans that use the Process could either be set with the new one by the wrapper or call the ProcessWrapper which would delegate to the Process.
class ProcessWrapper {
private Repository repository;
private Process process;
// getters, setters, etc.
public void do() {
process.do();
}
public void setProcess(Process process) {
this.process = process;
this.process.setRepository(repository);
}
}

Answering my own question: how I've solved the problem so far is to create a base class which serializes and deserializes using a cheap little proxy. The proxy contains only the name of the bean.
You'll note that it uses a global to access the Spring context; a more elegant solution might store the context in a thread-local variable, something like that.
public abstract class CheaplySerializableBase
implements Serializable, BeanNameAware {
private String name;
private static class SerializationProxy implements Serializable {
private final String name;
public SerializationProxy(CheaplySerializableBase target) {
this.name = target.name;
}
Object readResolve() throws ObjectStreamException {
return ContextLoader.globalEvilSpringContext.getBean(name);
}
}
#Override
public void setBeanName(String name) {
this.name = name;
}
protected Object writeReplace() throws ObjectStreamException {
if (name != null) {
return new SerializationProxy(this);
}
return this;
}
}
The resulting serialized object is 150 bytes or so (if I remember correctly).

The method applicationContext.getAutowireCapableBeanFactory().autowireBean(detachedBean); can be used to reconfigure a Spring-managed bean that was serialized and then de-serialized (whose #Autowired fields become null). See example below. The serialization details are omitted for simplicity.
public class DefaultFooService implements FooService {
#Autowired
private ApplicationContext ctx;
#Override
public SerializableBean bar() {
SerializableBean detachedBean = performAction();
ctx.getAutowireCapableBeanFactory().autowireBean(detachedBean);
return detachedBean;
}
private SerializableBean performAction() {
SerializableBean outcome = ... // Obtains a deserialized instance, whose #Autowired fields are detached.
return outcome;
}
}
public class SerializableBean {
#Autowired
private transient BarService barService;
private int value;
public void doSomething() {
barService.doBar(value);
}
}

How to get the set of beans that are to be created in Spring?

So here's the scenario:
I have a Spring XML configuration with some lazy-beans, some not lazy-beans and some beans that depend on other beans. Eventually Spring will resolve all this so that only the beans that are meant to be created are created.
The question: how can I programmatically tell what this set is?
When I use context.getBean(name) that initializes the bean. BeanDefinition.isLazyInit() will only tell me how I defined the bean.
Any other ideas?
ETA:
In DefaultListableBeanFactory:
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isInfoEnabled()) {
this.logger.info("Pre-instantiating singletons in " + this);
}
synchronized (this.beanDefinitionMap) {
for (Iterator it = this.beanDefinitionNames.iterator(); it.hasNext();) {
String beanName = (String) it.next();
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
if (isFactoryBean(beanName)) {
FactoryBean factory = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName);
if (factory instanceof SmartFactoryBean && ((SmartFactoryBean) factory).isEagerInit()) {
getBean(beanName);
}
}
else {
getBean(beanName);
}
}
}
}
}
The set of instantiable beans is initialized. When initializing this set any beans not in this set referenced by this set will also be created. From looking through the source it does not look like there's going to be any easy way to answer my question.

Perhaps
ApplicationContext.getBeanDefinitionNames()
Note that there is no (decent) way to determine which beans will be instantiated and which won't. If you are using ApplicationContextAware, you get access to all the beans at runtime, which makes this unpredictable.

So far my solution is:
Create ExtendedApplicationContext implementing ApplicationContextAware
Have the beans call initialized(this) on a static instance of ExtendedApplicationContext
Use this set plus the set of all bean definitions that are not singletons, abstract or lazy-initialized to create the set of intialized beans in ExtendedApplicationContext
Any better suggestions are welcome.

This is probably the best way, using a BeanPostProcessor:
public class IsIntializedBeanPostProcessor implements BeanPostProcessor {
private Set<String> initializedBeanNames = new HashSet<String>();
#Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
return bean;
}
#Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
initializedBeanNames.add(beanName);
return bean;
}
public Set<String> getInitializedBeanNames() {
return initializedBeanNames;
}
}
Then all you have to do is include this as a bean somewhere in the Spring config in order for it to work.

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