Java: Enum : NoClassDefFoundError

Question

在我的J2EE应用程序中使用枚举时，我面临一些问题。我在我的无状态服务bean中的开关案例中使用了enum。

在运行时，我看到以下异常发生在开关语句上：

Caused by: java.lang.NoClassDefFoundError: com/comp/service/TestServiceImpl$1

这个问题已经在SO的一个线程上进行了广泛的讨论。但是，我看不出有任何解决办法来解决这个问题。

在我的例子中，我使用JBossEAP6.1服务器。JDK版本为1.7。代码是在Eclipse中使用Maven构建的。应用程序部署为EAR存档。如何在我的EAR存档中的类路径中添加这个额外生成的类文件？还有其他办法来解决这个问题吗？

2014年6月29日更新：I试图从命令行构建应用程序。然后生成这个额外的类文件。而且我能够成功地节约和执行应用程序。这似乎是日食的错误。知道怎么解决吗？

来自EAR项目的pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <artifactId>demo-maven</artifactId>
        <groupId>com.comp.demo</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <artifactId>demo-ear</artifactId>
    <packaging>ear</packaging>

    <name>demo - ear</name>

    <url>www.comp.com</url>
    <licenses>
        <license>
            <name>Apache License, Version 2.0</name>
            <distribution>repo</distribution>
            <url>http://www.apache.org/licenses/LICENSE-2.0.html</url>
        </license>
    </licenses>

    <dependencies>

        <!-- Depend on the ejb module and war so that we can package them -->
        <dependency>
            <groupId>com.comp.demo</groupId>
            <artifactId>demo-web</artifactId>
            <type>war</type>
        </dependency>
        <dependency>
            <groupId>com.comp.demo</groupId>
            <artifactId>demo-service</artifactId>
            <type>ejb</type>
        </dependency>
    </dependencies>

    <build>
        <finalName>${project.parent.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-ear-plugin</artifactId>
                <version>${version.ear.plugin}</version>
                <configuration>
                    <!-- Tell Maven we are using Java EE 6 -->
                    <version>6</version>
                    <!-- Use Java EE ear libraries as needed. Java EE ear libraries 
                        are in easy way to package any libraries needed in the ear, and automatically 
                        have any modules (EJB-JARs and WARs) use them -->
                    <defaultLibBundleDir>lib</defaultLibBundleDir>
                    <modules></modules>
                    <fileNameMapping>no-version</fileNameMapping>
                </configuration>
            </plugin>
            <!-- The JBoss AS plugin deploys your ear to a local JBoss EAP container -->
            <!-- Due to Maven's lack of intelligence with EARs we need to configure 
                the jboss-as maven plugin to skip deployment for all modules. We then enable 
                it specifically in the ear module. -->
            <plugin>
                <groupId>org.jboss.as.plugins</groupId>
                <artifactId>jboss-as-maven-plugin</artifactId>
                <configuration>
                    <skip>false</skip>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <profiles>
        <profile>
            <!-- When built in OpenShift the 'openshift' profile will be used when invoking mvn. -->
            <!-- Use this profile for any OpenShift specific customization your app will need. -->
            <!-- By default that is to put the resulting archive into the 'deployments' folder. -->
            <!-- http://maven.apache.org/guides/mini/guide-building-for-different-environments.html -->
            <id>openshift</id>
            <build>
                <plugins>
                    <plugin>
                        <artifactId>maven-ear-plugin</artifactId>
                        <version>${version.ear.plugin}</version>
                        <configuration>
                            <outputDirectory>deployments</outputDirectory>
                        </configuration>
                    </plugin>
                </plugins>
            </build>
        </profile>
    </profiles>

</project>

来自ejb项目的pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <artifactId>demo-maven</artifactId>
        <groupId>com.comp.demo</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <artifactId>demo-service</artifactId>
    <packaging>ejb</packaging>

    <name>demo - service</name>

    <url>www.comp.com</url>
    <licenses>
        <license>
            <name>Apache License, Version 2.0</name>
            <distribution>repo</distribution>
            <url>http://www.apache.org/licenses/LICENSE-2.0.html</url>
        </license>
    </licenses>

    <dependencies>

        <!-- Declare the APIs we depend on and need for compilation. All of them 
            are provided by JBoss EAP 6 -->

        <!-- Import the EJB API, we use provided scope as the API is included in 
            JBoss EAP 6 -->
        <dependency>
            <groupId>org.jboss.spec.javax.ejb</groupId>
            <artifactId>jboss-ejb-api_3.1_spec</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- Import the CDI API, we use provided scope as the API is included in 
            JBoss EAP 6 -->
        <dependency>
            <groupId>javax.enterprise</groupId>
            <artifactId>cdi-api</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- Import the JPA API, we use provided scope as the API is included in 
            JBoss EAP 6 -->
        <dependency>
            <groupId>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.0-api</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- JSR-303 (Bean Validation) Implementation -->
        <!-- Provides portable constraints such as @Email -->
        <!-- Hibernate Validator is shipped in JBoss EAP 6 -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <scope>provided</scope>
        </dependency>


        <dependency>
            <groupId>org.jboss.ejb3</groupId>
            <artifactId>jboss-ejb3-ext-api</artifactId>
            <version>2.0.0-redhat-2</version>
            <type>jar</type>
            <scope>provided</scope>
        </dependency>

        <!-- Test scope dependencies -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-all</artifactId>
            <version>1.9.5</version>
            <scope>test</scope>
        </dependency>
        <dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-entitymanager</artifactId>
    <version>4.3.5.Final</version>
    <scope>test</scope>
</dependency>


        <!-- Optional, but highly recommended -->
        <!-- Arquillian allows you to test enterprise code such as EJBs and Transactional(JTA) 
            JPA from JUnit/TestNG -->
        <dependency>
            <groupId>org.jboss.arquillian.junit</groupId>
            <artifactId>arquillian-junit-container</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.jboss.arquillian.protocol</groupId>
            <artifactId>arquillian-protocol-servlet</artifactId>
            <scope>test</scope>
        </dependency>

<dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>6.0</version>
            <type>jar</type>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <artifactId>maven-ejb-plugin</artifactId>
                <version>${version.ejb.plugin}</version>
                <configuration>
                    <!-- Tell Maven we are using EJB 3.1 -->
                    <ejbVersion>3.1</ejbVersion>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <profiles>
        <profile>
            <!-- The default profile skips all tests, though you can tune it to run 
                just unit tests based on a custom pattern -->
            <!-- Seperate profiles are provided for running all tests, including Arquillian 
                tests that execute in the specified container -->
            <id>default</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <build>
                <plugins>
                    <plugin>
                        <artifactId>maven-surefire-plugin</artifactId>
                        <version>${version.surefire.plugin}</version>
                        <configuration>
                            <skip>true</skip>
                        </configuration>
                    </plugin>
                </plugins>
            </build>
        </profile>

        <profile>
            <!-- An optional Arquillian testing profile that executes tests in your 
                JBoss EAP instance -->
            <!-- This profile will start a new JBoss EAP instance, and execute the 
                test, shutting it down when done -->
            <!-- Run with: mvn clean test -Parq-jbossas-managed -->
            <id>arq-jbossas-managed</id>
            <dependencies>
                <dependency>
                    <groupId>org.jboss.as</groupId>
                    <artifactId>jboss-as-arquillian-container-managed</artifactId>
                    <scope>test</scope>
                </dependency>
            </dependencies>
        </profile>

        <profile>
            <!-- An optional Arquillian testing profile that executes tests in a remote 
                JBoss EAP instance -->
            <!-- Run with: mvn clean test -Parq-jbossas-remote -->
            <id>arq-jbossas-remote</id>
            <dependencies>
                <dependency>
                    <groupId>org.jboss.as</groupId>
                    <artifactId>jboss-as-arquillian-container-remote</artifactId>
                    <scope>test</scope>
                </dependency>
            </dependencies>
        </profile>

    </profiles>

</project>

Answer 1

我遇到了一个类似的问题，简单的解决办法是将Enum定义为公共的，而不是私有的。

(没有时间进行验证，但我的直觉是，这导致类不是以名称$1类创建的，而是类似于似乎是问题所在的类)。

Answer 2

在我的示例中，为了避免开关语句的代码行中的NoClassDefFoundError，我看到的唯一解决方案是将开关语句替换为"else if“语句：

        if (enumValue == EnumClass.Enum1) {
            ....
        } else if (enumValue == EnumClass.Enum2) {
            ....
        } else if (enumValue == EnumClass.Enum3) {
            ....
        } else {
            ....
        }

因下列原因造成的例外：

Caused by: java.lang.ClassNotFoundException: com.test.services.impl.MyServiceImpl$1
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1358)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)

用Java 8，Tomcat8.5，Spring进行测试。

Answer 3

我有一个与您非常相似的项目配置: eclipse、Maven、JDK1.6、JBoss EAP6.2，在开关情况下使用枚举时，java.lang.NoClassDefFoundError也有同样的问题。

我找到了一个解决办法:生成一个ear文件(在我的例子中是war )，然后从JBoss管理控制台手动安装它。我注意到战争包括$1所需的类，然后你就不会得到例外。

这只是个解决办法，但对我来说很管用。解决这个问题的一个好方法是通过eclipse完成后续部署！

我将倾听你问题的答案，因为我想要一个真正的解决方案。