我遇到了EJB 3.1单例的问题。我创建了一个简单的项目来查看我是否能够正确地实例化它们，但是，由于Glassfish 3.1.2.2的长期异常，看起来我正在做错误的开始。
我正在使用maven将其编译为WAR（没有web.xml描述符）。我正在使用jax-rs w / Jersey来处理休息呼叫。
看起来我无法实例化SingletonA（当我尝试部署应用程序时失败）。在调用带有@PostConstruct标记的方法时，不会注入/创建SingletonB。
对此的任何帮助将不胜感激。
这是我的POM
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>MyGroup</groupId>
<artifactId>myartifact</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>myproject</name>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.2</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>6.0</version>
</dependency>
</dependencies>
这是RestApp
package main;
import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;
@ApplicationPath("/rest/")
public class RestApp extends Application {
}
这是我的SingletonA
package main;
import javax.annotation.PostConstruct;
import javax.ejb.DependsOn;
import javax.ejb.Singleton;
import javax.ejb.Startup;
import javax.inject.Inject;
@Singleton
@Startup
@DependsOn("SingletonB")
public class SingletonA {
@Inject SingletonB sb;
@PostConstruct
public void init()
{
System.out.println("\n\n>In SingletonA's startup\n");
sb.doSomethingCool();
}
public String test()
{
return sb.getIt();
}
}
这是SingletonB
package main;
import javax.ejb.Singleton;
@Singleton
public class SingletonB {
public void doSomethingCool()
{
System.out.println("\n\n\n>>Singleton B did something cool!\n\n\n");
}
public String getIt()
{
return "my string";
}
}
休息服务：
package main;
import javax.ejb.Stateless;
import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
@Path("")
@Stateless
public class RestSvc {
@Inject SingletonA sa;
@Path("/get")
@GET
public String asdf()
{
return sa.test();
}
}
最后这是来自服务器的堆栈跟踪：
[#|2012-12-07T10:21:42.934-0700|SEVERE|glassfish3.1.2|javax.enterprise.system.tools.admin.org.glassfish.deployment.admin|_ThreadID=156;_ThreadName=Thread-2;|Exception while loading the app : javax.ejb.CreateException: Initialization failed for Singleton SingletonA
javax.ejb.CreateException: Initialization failed for Singleton SingletonA
at com.sun.ejb.containers.AbstractSingletonContainer.createSingletonEJB(AbstractSingletonContainer.java:547)
at com.sun.ejb.containers.AbstractSingletonContainer.access$100(AbstractSingletonContainer.java:79)
at com.sun.ejb.containers.AbstractSingletonContainer$SingletonContextFactory.create(AbstractSingletonContainer.java:719)
at com.sun.ejb.containers.AbstractSingletonContainer.instantiateSingletonInstance(AbstractSingletonContainer.java:451)
at org.glassfish.ejb.startup.SingletonLifeCycleManager.initializeSingleton(SingletonLifeCycleManager.java:216)
at org.glassfish.ejb.startup.SingletonLifeCycleManager.initializeSingleton(SingletonLifeCycleManager.java:177)
at org.glassfish.ejb.startup.SingletonLifeCycleManager.doStartup(SingletonLifeCycleManager.java:155)
at org.glassfish.ejb.startup.EjbApplication.start(EjbApplication.java:177)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:130)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:269)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:301)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:461)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:240)
at org.glassfish.deployment.admin.DeployCommand.execute(DeployCommand.java:389)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$1.execute(CommandRunnerImpl.java:348)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:363)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1085)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$1200(CommandRunnerImpl.java:95)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1291)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1259)
at org.glassfish.admin.rest.ResourceUtil.runCommand(ResourceUtil.java:214)
at org.glassfish.admin.rest.ResourceUtil.runCommand(ResourceUtil.java:207)
at org.glassfish.admin.rest.resources.TemplateListOfResource.createResource(TemplateListOfResource.java:148)
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 com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:205)
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288)
at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:134)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.SubLocatorRule.accept(SubLocatorRule.java:134)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1469)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1400)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1349)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1339)
at com.sun.jersey.server.impl.container.grizzly.GrizzlyContainer._service(GrizzlyContainer.java:182)
at com.sun.jersey.server.impl.container.grizzly.GrizzlyContainer.service(GrizzlyContainer.java:147)
at org.glassfish.admin.rest.adapter.RestAdapter.service(RestAdapter.java:148)
at com.sun.grizzly.tcp.http11.GrizzlyAdapter.service(GrizzlyAdapter.java:179)
at com.sun.enterprise.v3.server.HK2Dispatcher.dispath(HK2Dispatcher.java:117)
at com.sun.enterprise.v3.services.impl.ContainerMapper$Hk2DispatcherCallable.call(ContainerMapper.java:354)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.NullPointerException
at main.SingletonA.init(SingletonA.java:20)
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 com.sun.ejb.containers.interceptors.BeanCallbackInterceptor.intercept(InterceptorManager.java:1009)
at com.sun.ejb.containers.interceptors.CallbackChainImpl.invokeNext(CallbackChainImpl.java:65)
at com.sun.ejb.containers.interceptors.CallbackInvocationContext.proceed(CallbackInvocationContext.java:113)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doCallback(SystemInterceptorProxy.java:138)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.init(SystemInterceptorProxy.java:120)
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 com.sun.ejb.containers.interceptors.CallbackInterceptor.intercept(InterceptorManager.java:964)
at com.sun.ejb.containers.interceptors.CallbackChainImpl.invokeNext(CallbackChainImpl.java:65)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:393)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:376)
at com.sun.ejb.containers.AbstractSingletonContainer.createSingletonEJB(AbstractSingletonContainer.java:538)
... 62 more
|#]
答案 0 :(得分：1)
如果您的EJB是使用@EJB注入的，但未使用@Inject，则可能意味着您忘记在WEB-INF目录中添加beans.xml文件（甚至为空）。见http://docs.oracle.com/javaee/6/tutorial/doc/gjbnz.html。
答案 1 :(得分：0)
答案是在pom依赖项中。我不能给出任何更多的猜测，为什么这个修复它，但确实如此。如果有人知道为什么会这样，请发表评论原因。
这是我的新POM文件（我更改了依赖项。删除了javaee-api v6并改为使用了glassfish javax.ejb。
这个项目中没有web.xml或beans.xml（我已经阅读过EE 6，这些文件是可选的）
我再也不能使用@Inject了，所以我的所有注射都改为@EJB。有了这个，我能够成功地实例化两个单身，并毫无问题地注入它们。
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>MyGroup</groupId>
<artifactId>myartifact</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>myproject</name>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.2</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.glassfish</groupId>
<artifactId>javax.ejb</artifactId>
<version>3.1.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>jsr311-api</artifactId>
<version>1.1.1</version>
<scope>provided</scope>
</dependency>
</dependencies>
</project>