1

我遇到了 EJB 3.1 单例的问题。我创建了一个简单的项目，看看我是否可以让它们正确实例化，但是，由于 Glassfish 3.1.2.2 的一个长异常，看起来我开始做错了。

我正在使用 maven 将其编译成 WAR（没有 web.xml 描述符）。我正在使用带有 Jersey 的 jax-rs 来处理休息电话。

看起来我无法实例化 SingletonA（当我尝试部署应用程序时失败）。在调用标有 @PostConstruct 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
|#]
4

2 回答 2

1

如果您的 EJB 是使用 @EJB 注入的，但没有使用 @Inject，则可能意味着您忘记beans.xml在 WEB-INF 目录中添加一个文件（即使是空的）。请参阅http://docs.oracle.com/javaee/6/tutorial/doc/gjbnz.html。

于 2012-12-07T18:16:56.890 回答
0

答案在 pom 依赖项中。我只能猜测为什么会修复它，但它确实如此。如果有人知道为什么会这样，请留下评论为什么。

这是我的新 POM 文件（我更改了依赖项。删除了 javaee-api v6 并改用 glassfish javax.ejb。

这个项目中没有 web.xml 或 beans.xml（我在 EE 6 中读过，这些文件是可选的）

我不能再使用@Inject，所以我所有的注入都改成了@EJB。有了这个，我能够成功地实例化两个单例，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>
于 2012-12-07T20:39:08.123 回答