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findResource（“”） 在 module-info.java 存在时返回 null，这是为什么呢？

java java-10 spring-boot java-module java-platform-module-system
2022-08-31 20:40:46

我正在调试为什么在我的Spring Boot应用程序中存在，在启动期间引发异常。这是例外：module-info.javaspring-orm

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

我追踪了这个问题，如果存在，但如果不存在，就返回。URLClassLoader.findResource("")nullmodule-info.java"file:/C:/Users/pupeno/Documents/Dashman/code/dashmanserver/target/classes/"

我创建了引发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Moditect的最新副本：https://github.com/moditect/moditect 由于此错误修复尚未发布：https://github.com/moditect/moditect/issues/51
  2. 从以下位置克隆演示存储库：https://github.com/dashmantech/demo
  3. 使用凭据设置本地 PostgreSQL 数据库 demo/confi/application.properties
  4. 首先运行，以便 ModiTec 创建所有模块mvn clean package
  5. 在 IntelliJ 的最新副本中打开项目
  6. 单击“运行演示”配置文件的播放（该目录包含在相应的运行配置文件中，带有参数等）。.idea

我需要回来才能工作。findResource("")"file:/C:/Users/pupeno/Documents/Dashman/code/dashmanserver/target/classes/"spring-orm

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;
}

因此，我可以看到有一些访问正在进行中，无需使用模块系统即可，但是当存在时，Java的模块系统会阻止它。我的问题是我不知道如何使它工作，应该导出或打开什么才能工作？module-infe.java

Spring Boot 导致调用该方法的方式是 through ，具体来说，是第 124 行的子类，它调用：RestartClassLoaderURLClassLoadersuper.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));
}

正在使用的特定实例是 的成员，它以这种方式定义：RestartClassLoaderClassPathResource

this.classLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader());

在构造函数中，第 85 行。

最后，看起来像这样：getDefaultClassLoader()

/**
 * 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;
}

我的包含：module-info.java

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;
}

在IntelliJ中，我启用了以下插件：

  • 龙目岛插件
  • .ginore
  • PowerShell
  • VisualVM Launcher
  • 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
  • 格雷德尔
  • 槽的
  • 和留集成
  • HTML Tools
  • HTTP 客户端
  • l18n for Java
  • IDE 设置同步
  • Java Bytecode Decompiler
  • Java EE： EJB， JPA， Servlets
  • Java 流调试器
  • JavaFX
  • 联合
  • 生产线分拣机
  • 降价支持
  • Maven Integration
  • Maven Integration Extension
  • 持久性框架支持
  • 属性支持
  • 斯玛利支持
  • 弹簧 AOP/@AspectJ
  • 弹簧批次
  • 弹簧靴
  • 春季数据
  • 弹簧集成模式
  • 弹簧 OSGi
  • 弹簧安防
  • 弹簧支撑
  • 春季网络服务
  • 春季网络袜子
  • 终端
  • 亚姆尔

答案 1

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

我希望在（取决于您的Spring依赖项）中看到类似的东西：module-info.java

opens tech.flexpoint.dashman to spring.core, spring.beans, spring.context;

例外情况是 ，当无法在编译时解析已知类的类定义时，会在运行时引发，在本例中为接口 ，它是 Java 事务 API （JTA） 的一部分。NoClassDefFoundErrorjavax.transaction.UserTransaction

正如其他人所指出的，JTA没有与JDK捆绑在一起，需要作为编译依赖项添加。但是，需要加载类定义的类来自工件，工件负责自己的依赖项 （spring-boot-autoconfigure@2.4.0.RELEASEUserTransactionspring-boot-autoconfigure


答案 2

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