那些遇到过的问题

当module-info.java存在时,findResource("")返回null,为什么会这样？

pup*_*eno 51 java java-platform-module-system spring-boot java-10 java-module

我正在调试为什么在module-info.java我的Spring Boot应用程序中,spring-orm在启动时抛出异常.这是例外:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is java.lang.NoClassDefFoundError: javax/transaction/UserTransaction
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1699) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:573) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.context@5.0.8.RELEASE/org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1089) ~[spring-context-5.0.8.RELEASE.jar:na]
    at spring.context@5.0.8.RELEASE/org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:859) ~[spring-context-5.0.8.RELEASE.jar:na]
    at spring.context@5.0.8.RELEASE/org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.8.RELEASE.jar:na]
    at spring.boot@2.0.4.RELEASE/org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.4.RELEASE.jar:na]
    at spring.boot@2.0.4.RELEASE/org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762) [spring-boot-2.0.4.RELEASE.jar:na]
    at spring.boot@2.0.4.RELEASE/org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:398) [spring-boot-2.0.4.RELEASE.jar:na]
    at spring.boot@2.0.4.RELEASE/org.springframework.boot.SpringApplication.run(SpringApplication.java:330) [spring-boot-2.0.4.RELEASE.jar:na]
    at spring.boot@2.0.4.RELEASE/org.springframework.boot.SpringApplication.run(SpringApplication.java:1258) [spring-boot-2.0.4.RELEASE.jar:na]
    at spring.boot@2.0.4.RELEASE/org.springframework.boot.SpringApplication.run(SpringApplication.java:1246) [spring-boot-2.0.4.RELEASE.jar:na]
    at tech.flexpoint.dashmanserver/tech.flexpoint.dashmanserver.DashmanServerApplication.main(DashmanServerApplication.java:13) [classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
    at spring.boot.devtools@2.0.4.RELEASE/org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.0.4.RELEASE.jar:na]
Caused by: java.lang.NoClassDefFoundError: javax/transaction/UserTransaction
    at java.base/java.lang.Class.getDeclaredMethods0(Native Method) ~[na:na]
    at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3119) ~[na:na]
    at java.base/java.lang.Class.privateGetPublicMethods(Class.java:3144) ~[na:na]
    at java.base/java.lang.Class.getMethods(Class.java:1863) ~[na:na]
    at hibernate.core@5.2.17.Final/org.hibernate.service.internal.AbstractServiceRegistryImpl.applyInjections(AbstractServiceRegistryImpl.java:288) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:279) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:239) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.service.internal.SessionFactoryServiceRegistryImpl.getService(SessionFactoryServiceRegistryImpl.java:80) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.internal.SessionFactoryImpl.canAccessTransactionManager(SessionFactoryImpl.java:942) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.internal.SessionFactoryImpl.buildCurrentSessionContext(SessionFactoryImpl.java:953) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:319) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:462) ~[hibernate-core-5.2.17.Final.jar:na]
    at hibernate.core@5.2.17.Final/org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:892) ~[hibernate-core-5.2.17.Final.jar:na]
    at spring.orm@5.0.8.RELEASE/org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57) ~[spring-orm-5.0.8.RELEASE.jar:na]
    at spring.orm@5.0.8.RELEASE/org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.0.8.RELEASE.jar:na]
    at spring.orm@5.0.8.RELEASE/org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:390) ~[spring-orm-5.0.8.RELEASE.jar:na]
    at spring.orm@5.0.8.RELEASE/org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377) ~[spring-orm-5.0.8.RELEASE.jar:na]
    at spring.orm@5.0.8.RELEASE/org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1758) ~[spring-beans-5.0.8.RELEASE.jar:na]
    at spring.beans@5.0.8.RELEASE/org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1695) ~[spring-beans-5.0.8.RELEASE.jar:na]
    ... 21 common frames omitted
Caused by: java.lang.ClassNotFoundException: javax.transaction.UserTransaction
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582) ~[na:na]
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:190) ~[na:na]
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499) ~[na:na]
    ... 42 common frames omitted
Run Code Online (Sandbox Code Playgroud)

如果存在的话,我会将问题追溯到URLClassLoader.findResource("")返回,但如果不存在的话.nullmodule-info.java"file:/C:/Users/pupeno/Documents/Dashman/code/dashmanserver/target/classes/"

我创建了抛出相同异常的最小可能示例.要运行它,您需要:

  1. 从这里克隆并安装最新的Moditect副本:https://github.com/moditect/moditect由于此错误修复尚未解决:https://github.com/moditect/moditect/issues/51
  2. 从以下网址克隆演示回购:https://github.com/dashmantech/demo
  3. 使用凭证demo/confi/application.properties设置本地PostgreSQL数据库
  4. mvn clean package首先运行,以便ModiTec创建所有模块
  5. 在最近的IntelliJ副本中打开项目
  6. 单击"运行演示"配置文件的播放(该.idea目录包含在相应的运行配置文件中,带有参数等).

我需要findResource("")返回"file:/C:/Users/pupeno/Documents/Dashman/code/dashmanserver/target/classes/",这样spring-orm可以工作.

findResource("") 看起来像这样:

public URL findResource(final String name) {
    /*
     * The same restriction to finding classes applies to resources
     */
    URL url = AccessController.doPrivileged(
        new PrivilegedAction<>() {
            public URL run() {
                return ucp.findResource(name, true);
            }
        }, acc);

    return url != null ? URLClassPath.checkURL(url) : null;
}
Run Code Online (Sandbox Code Playgroud)

所以我可以看到有一些访问可以在不使用模块系统的情况下进行,但是当module-infe.java存在时,Java的模块系统会阻止它.我的问题是,我不知道如何使其工作,应该导出或打开它的工作？

Spring Boot引起该方法调用的方式是通过RestartClassLoader一个子类URLClassLoader,特别是第124行调用super.findResource(name):

@Override
public URL findResource(String name) {
    final ClassLoaderFile file = this.updatedFiles.getFile(name);
    if (file == null) {
        return super.findResource(name);
    }
    if (file.getKind() == Kind.DELETED) {
        return null;
    }
    return AccessController
            .doPrivileged((PrivilegedAction<URL>) () -> createFileUrl(name, file));
}
Run Code Online (Sandbox Code Playgroud)

RestartClassLoader正在使用的特定实例是一个成员,ClassPathResource它以这种方式定义:

this.classLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader());
Run Code Online (Sandbox Code Playgroud)

在构造函数中,第85行.

最后,getDefaultClassLoader()看起来像这样:

/**
 * Return the default ClassLoader to use: typically the thread context
 * ClassLoader, if available; the ClassLoader that loaded the ClassUtils
 * class will be used as fallback.
 * <p>Call this method if you intend to use the thread context ClassLoader
 * in a scenario where you clearly prefer a non-null ClassLoader reference:
 * for example, for class path resource loading (but not necessarily for
 * {@code Class.forName}, which accepts a {@code null} ClassLoader
 * reference as well).
 * @return the default ClassLoader (only {@code null} if even the system
 * ClassLoader isn't accessible)
 * @see Thread#getContextClassLoader()
 * @see ClassLoader#getSystemClassLoader()
 */
@Nullable
public static ClassLoader getDefaultClassLoader() {
    ClassLoader cl = null;
    try {
        cl = Thread.currentThread().getContextClassLoader();
    }
    catch (Throwable ex) {
        // Cannot access thread context ClassLoader - falling back...
    }
    if (cl == null) {
        // No thread context class loader -> use class loader of this class.
        cl = ClassUtils.class.getClassLoader();
        if (cl == null) {
            // getClassLoader() returning null indicates the bootstrap ClassLoader
            try {
                cl = ClassLoader.getSystemClassLoader();
            }
            catch (Throwable ex) {
                // Cannot access system ClassLoader - oh well, maybe the caller can live with null...
            }
        }
    }
    return cl;
}
Run Code Online (Sandbox Code Playgroud)

我的module-info.java包含:

module tech.flexpoint.dashman {
    exports tech.flexpoint.dashman to com.fasterxml.jackson.databind;
    exports tech.flexpoint.dashman.controllers.configurator to javafx.fxml;

    opens tech.flexpoint.dashman to javafx.graphics, jna;
    opens tech.flexpoint.dashman.controllers.common to javafx.fxml;
    opens tech.flexpoint.dashman.controllers.configurator to javafx.fxml;
    opens tech.flexpoint.dashman.models to org.hibernate.validator, tech.flexpoint.dashmancommon, javafx.base;

    opens common;
    opens configurator;
    opens displayer;
    opens winscreensaver;

    requires appdirs;
    requires org.bouncycastle.provider;
    requires com.fasterxml.jackson.core;
    requires com.fasterxml.jackson.databind;
    requires com.fasterxml.jackson.datatype.jdk8;
    requires io.sentry;
    requires jackson.annotations;
    requires java.desktop;
    requires java.sql;
    requires java.validation;
    requires javafx.controls;
    requires javafx.fxml;
    requires javafx.graphics;
    requires javafx.media;
    requires javafx.web;
    requires jna;
    requires jna.platform;
    requires org.apache.commons.lang3;
    requires org.kordamp.ikonli.javafx;
    requires org.kordamp.ikonli.fontawesome5;
    requires spring.core;
    requires spring.retry;
    requires spring.web;
    requires tech.flexpoint.dashmancommon;
}
Run Code Online (Sandbox Code Playgroud)

在IntelliJ中,我启用了这些插件:

  • Lombok插件
  • .ginore
  • 电源外壳
  • VisualVM启动器
  • ANSI荧光笔
  • 批处理脚本支持
  • 字节码查看器
  • CMD支持
  • 版权
  • 覆盖
  • CSS支持
  • 数据库工具和SQL
  • Git集成
  • GitHub上
  • 摇篮
  • Groovy的
  • Heroku整合
  • HTML工具
  • HTTP客户端
  • l18n for Java
  • IDE设置同步
  • Java字节码反编译器
  • Java EE:EJB,JPA,Servlets
  • Java Stream调试器
  • JavaFX的
  • JUnit的
  • 线路分拣机
  • 降价支持
  • Maven集成
  • Maven集成扩展
  • 持久性框架支持
  • 属性支持
  • Smali支持
  • Spring AOP/@ AspectJ
  • 春批
  • 春季启动
  • 春季数据
  • Spring集成模式
  • Spring OSGi
  • 春季安全
  • 弹簧支持
  • Spring Web Services
  • Spring WebSocket
  • 终奌站
  • YAML

Hen*_*rik 12

我注意到的一件事是你的应用程序(假设它被打包tech.flexpoint.dashman)似乎没有以任何方式打开Spring,这肯定会导致类加载/非法访问失败.

我希望看到这样的东西module-info.java(取决于你的Spring依赖项):

opens tech.flexpoint.dashman to spring.core, spring.beans, spring.context;
Run Code Online (Sandbox Code Playgroud)

异常是a NoClassDefFoundError,当在编译时已知的类的类定义无法解析时,在运行时抛出该异常,在这种情况下是接口javax.transaction.UserTransaction,它是Java Transaction API(JTA)的一部分.

正如其他人所指出的那样,JTA没有与JDK捆绑在一起,需要添加为编译依赖项.然而,需要加载类的UserTransaction类定义来自spring-boot-autoconfigure神器,负责自己的依赖(),所以你应该不会需要JTA添加作为一个依赖.spring-boot-autoconfigure@2.4.0.RELEASE jboss-transaction-spi@7.6.0.Final jboss-transaction-api_1.2_spec@1.1.1.Final

但是,因为您希望将自己的应用程序打包为Java 9模块,所以需要显式声明其依赖关系.spring-boot-autoconfigure还不是一个模块化的Java 9库,并没有为你做这个(即传递).JTA的自动模块名称是java.transaction,因此您需要在以下位置添加要求module-info.java:

requires java.transaction;
Run Code Online (Sandbox Code Playgroud)

我让你的例子运行,并且NoClassDefFoundError从IntelliJ IDEA运行时确实得到了.stacktrace指向a ClassNotFoundException,表示类路径问题.由于IDEA在从那里启动应用程序时计算类路径,我想看看在使用spring-boot-maven-plugin运行应用程序时是否可以重现错误.

我将IDEA运行配置复制到spring-boot-maven-plugin配置中,如下所示:

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <configuration>
      <mainClass>tech.flexpoint.demo.DemoApplication</mainClass>
      <jvmArguments>--show-module-resolution --add-opens=java.base/java.lang=spring.core --add-opens=java.base/java.io=tomcat.embed.core --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.rmi/sun.rmi.transport=ALL-UNNAMED</jvmArguments>
      <workingDirectory>${project.basedir}</workingDirectory>
  </configuration>
</plugin>
Run Code Online (Sandbox Code Playgroud)

然后我调用了mvn spring-boot:run瞧,应用程序成功启动没有错误.我只能得出结论,这是IntelliJ计算的类路径的问题.

归档时间：

查看次数：

1264 次

最近记录：

7 年，1 月 前
JDK 9的Hibernate 5问题 5
更多相关链接
相关归档
在Java中反转一个字符串 437
为什么Java认为从10到99的所有数字的乘积都是0？ 132
Java编译速度与Scala编译速度 97
最有效的方法是使String小写的第一个字符？ 92
当文件存在时,File.exists()返回false 84
log4j:缩写/缩短包名 42
我可以使用 messages.yml 文件代替 messages.properties 作为消息代码吗 9
JobBuilderFactory.get(job).incrementer(RunIdIncrementer)的功能是什么？ 6
为什么 @UpdateTimestamp 在实体创建时默认设置一个值？ 6
Jackson 将 XML 与根序列化为抽象类 5
难疑归档
如何克隆特定的Git分支？ 2804
如何从Java中的字符串值获取枚举值？ 1890
在JavaScript中解析JSON？ 1642
什么是TypeScript,为什么我会用它代替JavaScript？ 1637
使用*args和**kwargs 1367
Git push需要用户名和密码 1327
在关系数据库中存储分层数据有哪些选项？ 1281
jQuery获取特定的选项标签文本 1211
有条件地申请课程的最佳方式是什么？ 1172
什么是"Linting"？ 1044