Java 11：在模块路径或类路径上找不到JAXB-API的实现

Question

我有一个小项目，当我让它运行时确实会引发异常。

问题在这里（TestObject.java）：

final JAXBContext jaxbContext = JAXBContext.newInstance(...);

我真的不明白为什么会抛出异常。我还创建了一个像超级按钮一样工作的测试（TestTest.java）。请原谅我的名字，但这只是一个小的测试应用程序，它可以与Java 11一起使用。

我遵循以下步骤：javax.xml.bind.JAXBException在模块路径或类路径上未找到 并添加了JAXB-API的实现

compile('javax.xml.bind:jaxb-api:2.3.0')
compile('javax.activation:activation:1.1')
compile('org.glassfish.jaxb:jaxb-runtime:2.3.0')

到我的build.gradle，但随后它抱怨

Error:java: module not found: java.activation

不见了。由于这也从Java 11中删除，因此我添加了：

compile 'com.sun.activation:javax.activation:1.2.0'

但随后引发了很多错误：

Error:java: the unnamed module reads package com.sun.xml.bind from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.util from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.marshaller from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.api from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.v2 from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.v2.util from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.v2.model.impl from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.v2.model.annotation from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.v2.runtime from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.v2.runtime.unmarshaller from both jaxb.runtime and jaxb.core
Error:java: the unnamed module reads package com.sun.xml.bind.unmarshaller from both jaxb.runtime and jaxb.core
Error:java: module jaxb.runtime reads package com.sun.xml.bind from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.util from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.marshaller from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.api from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.v2 from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.v2.util from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.v2.model.impl from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.v2.model.annotation from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.v2.runtime from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.v2.runtime.unmarshaller from both jaxb.core and jaxb.runtime
Error:java: module jaxb.runtime reads package com.sun.xml.bind.unmarshaller from both jaxb.core and jaxb.runtime
Error:java: module jaxb.core reads package com.sun.xml.bind from both jaxb.core and jaxb.runtime

令我感到困惑的是：测试有效。因此，似乎在junit5环境中存在某种jaxb实现。在如何将Java 8应用程序迁移到Java 9模块中，我还发现了其他一些信息：

compile group: 'javax.xml.bind', name: 'jaxb-api', version: '2.4.0-b180830.0359'
compile group: 'org.glassfish.jaxb', name: 'jaxb-runtime', version: '2.4.0-b180830.0438'
compile group: 'org.glassfish.jaxb', name: 'jaxb-xjc', version: '2.4.0-b180830.0438'

但这也不起作用。如果有人可以帮助我实现目标，我将非常高兴。我在64位Fedora 29上使用java-openjdk-11.0.1.13-11.rolling.fc29.x86_64。

ps .：我想将所有内容写到主题为“ javax.xml.bind.JAXBException ...”的帖子的注释中，但我不允许这样做。所以我创建了这个新帖子。

编辑：在该示例应用程序中引发的异常是：

Exception in thread "main" java.lang.RuntimeException: javax.xml.bind.JAXBException: Implementation of JAXB-API has not been found on module path or classpath.
 - with linked exception:
[java.lang.ClassNotFoundException: com.sun.xml.bind.v2.ContextFactory]
    at test/com.example.TestObject.doSomething(TestObject.java:21)
    at test/com.example.TestObject.main(TestObject.java:12)
Caused by: javax.xml.bind.JAXBException: Implementation of JAXB-API has not been found on module path or classpath.
 - with linked exception:
[java.lang.ClassNotFoundException: com.sun.xml.bind.v2.ContextFactory]
    at java.xml.bind/javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:269)
    at java.xml.bind/javax.xml.bind.ContextFinder.find(ContextFinder.java:412)
    at java.xml.bind/javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:721)
    at java.xml.bind/javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:662)
    at test/com.example.TestObject.doSomething(TestObject.java:17)
    ... 1 more
Caused by: java.lang.ClassNotFoundException: com.sun.xml.bind.v2.ContextFactory
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    at java.xml.bind/javax.xml.bind.ServiceLoaderUtil.nullSafeLoadClass(ServiceLoaderUtil.java:122)
    at java.xml.bind/javax.xml.bind.ServiceLoaderUtil.safeLoadClass(ServiceLoaderUtil.java:155)
    at java.xml.bind/javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:267)
    ... 5 more

Answer 1

当升级到SpringBoot 2.5时，我收到了同样的异常。添加以下依赖项（Maven）解决了我的问题：

<dependency>
    <groupId>org.glassfish.jaxb</groupId>
    <artifactId>jaxb-runtime</artifactId>
</dependency>

Answer 2

为了完成其他答案：

JAXB 使用绑定到当前线程的类加载器来查找 JAXBContextFactory类 ( Thread.currentThread().getContextClassLoader())，并且在某些情况下（例如使用 jetty 线程），绑定的类加载器是 a ，它具有不知道 class-path 的PlatformClassLoader特殊性，这与。AppClassLoader

要解决此问题，JAXB API 和运行时必须位于模块路径中（可通过 访问PlatformClassLoader）。

例如，应用程序打包时具有以下依赖项：

<dependency>
    <groupId>jakarta.xml.bind</groupId>
    <artifactId>jakarta.xml.bind-api</artifactId>
    <version>2.3.3</version>
</dependency>
<dependency>
    <groupId>org.glassfish.jaxb</groupId>
    <artifactId>jaxb-runtime</artifactId>
    <version>2.3.3</version>
</dependency>

因此，应用程序应该以其jaxb-runtime模块依赖项启动，如下所示：

### Set the module-path
MODULEPATH="./lib/jaxb-runtime-2.3.3.jar"
MODULEPATH="${MODULEPATH}:./lib/jakarta.activation-1.2.2.jar"
MODULEPATH="${MODULEPATH}:./lib/jakarta.xml.bind-api-2.3.3.jar"
MODULEPATH="${MODULEPATH}:./lib/txw2-2.3.3.jar"
MODULEPATH="${MODULEPATH}:./lib/istack-commons-runtime-3.0.11.jar"

java --module-path ${MODULEPATH} --add-modules ALL-MODULE-PATH [...]

注意：ALL-MODULE-PATH 可以替换为特定的模块名称

Answer 3

解决方案非常简单。首先，使用jaxb 2.3.1。Beta版资料仅供测试。真正的问题是module-info.java。jaxb必须具有2个条目：

requires java.xml.bind;
requires com.sun.xml.bind;

第一个要求定义实现，第二个要求API。

所需的仅两个依赖项是：

compile group: 'javax.xml.bind', name: 'jaxb-api', version: '2.3.1'
compile group: 'org.glassfish.jaxb', name: 'jaxb-runtime', version: '2.3.1'