我有一些使用JAXB API类的代码,这些类已作为Java 6/7/8中的JDK的一部分提供。当我用Java 9运行相同的代码时,在运行时得到错误,指示找不到JAXB类。

从Java 6开始,JAXB类就作为JDK的一部分提供了,那么为什么Java 9再也找不到这些类了呢?


当前回答

不是答案,而是一个附录:我得到的原因是,如果JAVA_HOME指向Java 9安装(准确地说是Java版本“9.0.1”),则运行groovysh (Groovy 2.4.13)会失败:

java.lang.reflect.InvocationTargetException
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.codehaus.groovy.tools.GroovyStarter.rootLoader(GroovyStarter.java:107)
        at org.codehaus.groovy.tools.GroovyStarter.main(GroovyStarter.java:129)
Caused by: java.lang.NoClassDefFoundError: Unable to load class groovy.xml.jaxb.JaxbGroovyMethods due to missing dependency javax/xml/bind/JAXBContext
        at org.codehaus.groovy.vmplugin.v5.Java5.configureClassNode(Java5.java:400)
        at org.codehaus.groovy.ast.ClassNode.lazyClassInit(ClassNode.java:277)
        at org.codehaus.groovy.ast.ClassNode.getMethods(ClassNode.java:397)
        ...
        ..
        .
        ..
        ...
        at org.codehaus.groovy.tools.shell.Groovysh.<init>(Groovysh.groovy:135)
        at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)
        at org.codehaus.groovy.tools.shell.Main.<init>(Main.groovy:66)
        at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)
        at org.codehaus.groovy.tools.shell.Main.main(Main.groovy:163)
... 6 more

解决方案是:

Go to the JAXB Project at github.io ("JAXB is licensed under a dual license - CDDL 1.1 and GPL 2.0 with Class-path Exception") Download jaxb-ri-2.3.0.zip Unzip wherever you put your java infrastructure files (in my case, /usr/local/java/jaxb-ri/). Other solution may exist (maybe via SDKMAN, I dunno) Make sure the jars in the lib subdirectory are on the CLASSPATH. I do it via a script started on bash startup, called /etc/profile.d/java.sh, where I added (among many other lines) the following loop:

打包到函数中…

function extend_qzminynshg {
   local BASE="/usr/local/java"
   for LIB in jaxb-api.jar  jaxb-core.jar  jaxb-impl.jar  jaxb-jxc.jar  jaxb-xjc.jar; do
      local FQLIB="$BASE/jaxb-ri/lib/$LIB"
      if [[ -f $FQLIB ]]; then
         export CLASSPATH=$FQLIB:$CLASSPATH
      fi
    done
}

extend_qzminynshg; unset extend_qzminynshg

它确实有效!

其他回答

你可以使用——add-modules=java.xml。bind JVM选项将xml绑定模块添加到JVM运行时环境。

例如:java——add-modules=java.xml。绑定XmlTestClass

好吧,我一直有同样的问题,但我使用的是Java 8,并不断得到这个错误,我尝试了大多数的解决方案。但事实证明,我的maven仍然指向java 9,即使我将全局java版本设置为8,只要我修复了它就能正常工作。

对于任何可能遇到这类问题的人,请参阅如何修复Maven以使用默认Java(已存档)

这招对我很管用:

<dependency>
    <groupId>javax.xml.bind</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.3.0</version>
</dependency>
<dependency>
    <groupId>org.eclipse.persistence</groupId>
    <artifactId>eclipselink</artifactId>
    <version>2.7.0</version>
</dependency>

更新

正如@Jasper所建议的,为了避免依赖于整个EclipseLink库,你也可以只依赖于EclipseLink MOXy:

Maven

<dependency>
    <groupId>org.eclipse.persistence</groupId>
    <artifactId>org.eclipse.persistence.moxy</artifactId>
    <version>2.7.3</version>
</dependency>

Gradle

compile group: 'org.eclipse.persistence', name: 'org.eclipse.persistence.moxy', version: '2.7.3'

作为我的Java 8应用程序的依赖项,该应用程序生成一个*.jar,它可以在JRE 8或JRE 9上运行,没有额外的参数。

此外,在使用JAXB API之前,需要在某处执行此命令:

System.setProperty("javax.xml.bind.JAXBContextFactory", "org.eclipse.persistence.jaxb.JAXBContextFactory");

到目前为止,作为一种变通方法,效果很好。不过,这看起来并不是一个完美的解决方案……

我在App中遇到了同样的问题,在模块级别构建。gradle添加了视图绑定和数据绑定。

早些时候

viewBinding {
    enabled = true
}

dataBinding {
    enabled = true
}

解决

dataBinding {
    enabled = true
}

在项目级构建中。Gradle使用如下

classpath 'com.android.tools.build:gradle:3.6.3'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.20"

2019年4月更新

JAXB版本的Changelong在https://javaee.github.io/jaxb-v2/doc/user-guide/ch02.html

摘录:

    4.1. Changes between 2.3.0.1 and 2.4.0

         JAXB RI is now JPMS modularized:

            All modules have native module descriptor.

            Removed jaxb-core module, which caused split package issue on JPMS.

            RI binary bundle now has single jar per dependency instead of shaded fat jars.

            Removed runtime class weaving optimization.

    4.2. Changes between 2.3.0 and 2.3.0.1

          Removed legacy technology dependencies:

            com.sun.xml.bind:jaxb1-impl

            net.java.dev.msv:msv-core

            net.java.dev.msv:xsdlib

            com.sun.xml.bind.jaxb:isorelax

    4.3. Changes between 2.2.11 and 2.3.0

          Adopt Java SE 9:

            JAXB api can now be loaded as a module.

            JAXB RI is able to run on Java SE 9 from the classpath.

            Addes support for java.util.ServiceLoader mechanism.

            Security fixes

权威链接在https://github.com/eclipse-ee4j/jaxb-ri#maven-artifacts

Maven coordinates for JAXB artifacts jakarta.xml.bind:jakarta.xml.bind-api: API classes for JAXB. Required to compile against JAXB. org.glassfish.jaxb:jaxb-runtime: Implementation of JAXB, runtime used for serialization and deserialization java objects to/from xml. JAXB fat-jar bundles: com.sun.xml.bind:jaxb-impl: JAXB runtime fat jar. In contrast to org.glassfish.jaxb artifacts, these jars have all dependency classes included inside. These artifacts does not contain JPMS module descriptors. In Maven projects org.glassfish.jaxb artifacts are supposed to be used instead.

jaxb:jaxb-runtime:jar:2.3.2

[INFO] +- org.glassfish.jaxb:jaxb-runtime:jar:2.3.2:compile
[INFO] |  +- jakarta.xml.bind:jakarta.xml.bind-api:jar:2.3.2:compile
[INFO] |  +- org.glassfish.jaxb:txw2:jar:2.3.2:compile
[INFO] |  +- com.sun.istack:istack-commons-runtime:jar:3.0.8:compile
[INFO] |  +- org.jvnet.staxex:stax-ex:jar:1.8.1:compile
[INFO] |  +- com.sun.xml.fastinfoset:FastInfoset:jar:1.2.16:compile
[INFO] |  \- jakarta.activation:jakarta.activation-api:jar:1.2.1:compile

原来的答案

我应该在Maven项目中为JAXB RI使用哪些构件?在Maven中,你可以使用这样的配置文件:

<profile>
    <id>java-9</id>
    <activation>
        <jdk>9</jdk>
    </activation>
    <dependencies>
        <dependency>
            <groupId>org.glassfish.jaxb</groupId>
            <artifactId>jaxb-runtime</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>javax.activation</groupId>
            <artifactId>activation</artifactId>
            <version>1.1.1</version>
        </dependency>
    </dependencies>
</profile> 

依赖树显示:

[INFO] +- org.glassfish.jaxb:jaxb-runtime:jar:2.3.0:compile
[INFO] |  +- org.glassfish.jaxb:jaxb-core:jar:2.3.0:compile
[INFO] |  |  +- javax.xml.bind:jaxb-api:jar:2.3.0:compile
[INFO] |  |  +- org.glassfish.jaxb:txw2:jar:2.3.0:compile
[INFO] |  |  \- com.sun.istack:istack-commons-runtime:jar:3.0.5:compile
[INFO] |  +- org.jvnet.staxex:stax-ex:jar:1.7.8:compile
[INFO] |  \- com.sun.xml.fastinfoset:FastInfoset:jar:1.2.13:compile
[INFO] \- javax.activation:activation:jar:1.1.1:compile

要在Eclipse中使用它,请输入Oxygen.3a Release (4.7.3a)或更高版本,按Ctrl-Alt-P,或右键单击项目Maven,然后选择概要文件。