草庐IT

java.io.IOException : invalid constant type: 19 at 5 异常

coder 2024-03-19 原文

我有一个 project .它使用 spring boot 2、java 9 和 maven。它可以使用mvn clean package 成功构建。

要运行 spring boot 应用程序，我使用了命令

java -jar java-cloud-rest-api/target/java-cloud-rest-api-0.0.1-SNAPSHOT.jar

但是失败了，报错了

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; n
ested exception is java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1716) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:499) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1083) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:858) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:122) ~[spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at com.lapots.breed.platform.cloud.boot.app.JavaCloudSampleApplication.main(JavaCloudSampleApplication.java:10) [classes!/:0.0.1-SNAPSHOT]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
        at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na]
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
Caused by: java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
        at org.hibernate.boot.spi.XmlMappingBinderAccess.<init>(XmlMappingBinderAccess.java:43) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.boot.MetadataSources.<init>(MetadataSources.java:87) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.<init>(EntityManagerFactoryBuilderImpl.java:208) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.<init>(EntityManagerFactoryBuilderImpl.java:163) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:51) ~[spring-orm-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:358) ~[spring-orm-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:384) ~[spring-orm-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:373) ~[spring-orm-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1776) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1712) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        ... 24 common frames omitted
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.JAXBException
        at java.base/java.net.URLClassLoader.findClass(Unknown Source) ~[na:na]
        at java.base/java.lang.ClassLoader.loadClass(Unknown Source) ~[na:na]
        at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:93) ~[java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at java.base/java.lang.ClassLoader.loadClass(Unknown Source) ~[na:na]
        ... 34 common frames omitted

我在启动命令中添加了额外的参数

java --add-modules java.xml.bind -jar java-cloud-rest-api/target/java-cloud-rest-api-0.0.1-SNAPSHOT.jar

但是当我运行它的时候，我得到了这个错误

java.lang.ClassCastException: org.springframework.boot.context.event.ApplicationFailedEvent cannot be cast to org.springframework.boot.web.context.WebServerInitializedEvent
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:159) [spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) [spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127) [spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.boot.context.event.EventPublishingRunListener.finished(EventPublishingRunListener.java:114) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplicationRunListeners.callFinishedListener(SpringApplicationRunListeners.java:79) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplicationRunListeners.finished(SpringApplicationRunListeners.java:72) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:803) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:338) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at com.lapots.breed.platform.cloud.boot.app.JavaCloudSampleApplication.main(JavaCloudSampleApplication.java:10) [classes!/:0.0.1-SNAPSHOT]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
        at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na]
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]

2017-09-09 18:03:42.242  INFO 9200 --- [           main] utoConfigurationReportLoggingInitializer :

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-09-09 18:03:42.242 ERROR 9200 --- [           main] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/H
ibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.boot.archive.spi.ArchiveException: Could not build ClassFile
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1716) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]

        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:499) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1083) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:858) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:122) ~[spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233) [spring-boot-2.0.0.M3.jar!/:2.0.0.M3]
        at com.lapots.breed.platform.cloud.boot.app.JavaCloudSampleApplication.main(JavaCloudSampleApplication.java:10) [classes!/:0.0.1-SNAPSHOT]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
        at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na]
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) [java-cloud-rest-api-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
Caused by: org.hibernate.boot.archive.spi.ArchiveException: Could not build ClassFile
        at org.hibernate.boot.archive.scan.spi.ClassFileArchiveEntryHandler.toClassFile(ClassFileArchiveEntryHandler.java:64) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.boot.archive.scan.spi.ClassFileArchiveEntryHandler.handleEntry(ClassFileArchiveEntryHandler.java:47) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.boot.archive.internal.JarFileBasedArchiveDescriptor.visitArchive(JarFileBasedArchiveDescriptor.java:146) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.boot.archive.scan.spi.AbstractScannerImpl.scan(AbstractScannerImpl.java:47) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.boot.model.process.internal.ScanningCoordinator.coordinateScan(ScanningCoordinator.java:75) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.prepare(MetadataBuildingProcess.java:98) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.<init>(EntityManagerFactoryBuilderImpl.java:228) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.<init>(EntityManagerFactoryBuilderImpl.java:163) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:51) ~[spring-orm-5.0.0.RC3.
jar!/:5.0.0.RC3]
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:358) ~[spring-orm-5.0.0.RC3.jar!/:5
.0.0.RC3]
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:384) ~[spring-orm-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:373) ~[spring-orm-5.0.0.RC3.jar!/:5.0.0.RC3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1776) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.R
C3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1712) ~[spring-beans-5.0.0.RC3.jar!/:5.0.0.RC3]

        ... 24 common frames omitted
Caused by: java.io.IOException: invalid constant type: 19 at 5
        at javassist.bytecode.ConstPool.readOne(ConstPool.java:1244) ~[javassist-3.21.0-GA.jar!/:na]
        at javassist.bytecode.ConstPool.read(ConstPool.java:1175) ~[javassist-3.21.0-GA.jar!/:na]
        at javassist.bytecode.ConstPool.<init>(ConstPool.java:185) ~[javassist-3.21.0-GA.jar!/:na]
        at javassist.bytecode.ClassFile.read(ClassFile.java:829) ~[javassist-3.21.0-GA.jar!/:na]
        at javassist.bytecode.ClassFile.<init>(ClassFile.java:154) ~[javassist-3.21.0-GA.jar!/:na]
        at org.hibernate.boot.archive.scan.spi.ClassFileArchiveEntryHandler.toClassFile(ClassFileArchiveEntryHandler.java:61) ~[hibernate-core-5.2.10.Final.jar!/:5.2.10.Final]
        ... 37 common frames omitted

问题是什么？

最佳答案

虽然这没有回答如何解决这个问题，但如 JDK-8161256 中所述关于常量池标签:

Java 9 uses codes 19 and 20 for the module system.

目前 javassist 创建 ClassFile 的方式是在 ConstantPool 中查找(Java8 之前的表格)使用 readOne方法肯定缺少像最新 java 版本的 Module 之类的东西。 javassist 的依赖层次结构:

  • org.springframework.boot:spring-boot-starter-actuator:jar:2.0.0.M3:compile

    • org.springframework.boot:spring-boot-starter-data-jpa:jar:2.0.0.M3:compile

      • org.hibernate:hibernate-core:jar:5.2.10.Final:compile

        • org.javassist:javassist:jar:3.21.0-GA:compile

查看 javassist事物的一面:

  • 似乎在 javassist/issues#147 上注册了一个类似的错误.

  • rel_3_22_0_cr2 (最新版本)来自他们 显示为与 Java 9-ea+164 兼容。此版本的 javassist 也会出现同样的问题。

  • 所以您可以等待 javassist 返回解决方案。

关于java.io.IOException : invalid constant type: 19 at 5 异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46132019/

IOExceptionconstantspringframeworkjavabootmavenspring-bootjavassistjava-9

有关java.io.IOException : invalid constant type: 19 at 5 异常的更多相关文章

  1. ruby - 如何使用 Nokogiri 的 xpath 和 at_xpath 方法 - 2

    我正在学习如何使用Nokogiri，根据这段代码我遇到了一些问题:require'rubygems'require'mechanize'post_agent=WWW::Mechanize.newpost_page=post_agent.get('http://www.vbulletin.org/forum/showthread.php?t=230708')puts"\nabsolutepathwithtbodygivesnil"putspost_page.parser.xpath('/html/body/div/div/div/div/div/table/tbody/tr/td/div

  2. java - 等价于 Java 中的 Ruby Hash - 2

    我真的很习惯使用Ruby编写以下代码:my_hash={}my_hash['test']=1Java中对应的数据结构是什么？ 最佳答案 HashMapmap=newHashMap();map.put("test",1);我假设？ 关于java-等价于Java中的RubyHash，我们在StackOverflow上找到一个类似的问题： https://stackoverflow.com/questions/22737685/

  3. ruby-on-rails - Rails - 乐观锁定总是触发 StaleObjectError 异常 - 2

    我正在学习Rails，并阅读了关于乐观锁的内容。我已将类型为integer的lock_version列添加到我的articles表中。但现在每当我第一次尝试更新记录时，我都会收到StaleObjectError异常。这是我的迁移:classAddLockVersionToArticle当我尝试通过Rails控制台更新文章时:article=Article.first=>#我这样做:article.title="newtitle"article.save我明白了:(0.3ms)begintransaction(0.3ms)UPDATE"articles"SET"title"='dwdwd

  4. ruby - ＃之间？ Cooper 的 *Beginning Ruby* 中的错误或异常 - 2

    在Cooper的书BeginningRuby中，第166页有一个我无法重现的示例。classSongincludeComparableattr_accessor:lengthdef(other)@lengthother.lengthenddefinitialize(song_name,length)@song_name=song_name@length=lengthendenda=Song.new('Rockaroundtheclock',143)b=Song.new('BohemianRhapsody',544)c=Song.new('MinuteWaltz',60)a.betwee

  5. ruby - 如何验证 IO.copy_stream 是否成功 - 2

    这里有一个很好的答案解释了如何在Ruby中下载文件而不将其加载到内存中:https://stackoverflow.com/a/29743394/4852737require'open-uri'download=open('http://example.com/image.png')IO.copy_stream(download,'~/image.png')我如何验证下载文件的IO.copy_stream调用是否真的成功——这意味着下载的文件与我打算下载的文件完全相同，而不是下载一半的损坏文件？documentation说IO.copy_stream返回它复制的字节数，但是当我还没有下

  6. Ruby 文件 IO 定界符？ - 2

    我正在尝试解析一个文本文件，该文件每行包含可变数量的单词和数字，如下所示:foo4.500bar3.001.33foobar如何读取由空格而不是换行符分隔的文件？有什么方法可以设置File("file.txt").foreach方法以使用空格而不是换行符作为分隔符？ 最佳答案 接受的答案将slurp文件，这可能是大文本文件的问题。更好的解决方案是IO.foreach.它是惯用的，将按字符流式传输文件:File.foreach(filename,""){|string|putsstring}包含“thisisanexample”结果的

  7. ruby - 在 Ruby 中重新分配常量时抛出异常？ - 2

    我早就知道Ruby中的“常量”(即大写的变量名)不是真正常量。与其他编程语言一样，对对象的引用是唯一存储在变量/常量中的东西。(侧边栏:Ruby确实具有“卡住”引用对象不被修改的功能，据我所知，许多其他语言都没有提供这种功能。)所以这是我的问题:当您将一个值重新分配给常量时，您会收到如下警告:>>FOO='bar'=>"bar">>FOO='baz'(irb):2:warning:alreadyinitializedconstantFOO=>"baz"有没有办法强制Ruby抛出异常而不是打印警告？很难弄清楚为什么有时会发生重新分配。 最佳答案

  8. java - 从 JRuby 调用 Java 类的问题 - 2

    我正在尝试使用boilerpipe来自JRuby。我看过guide从JRuby调用Java，并成功地将它与另一个Java包一起使用，但无法弄清楚为什么同样的东西不能用于boilerpipe。我正在尝试基本上从JRuby中执行与此Java等效的操作:URLurl=newURL("http://www.example.com/some-location/index.html");Stringtext=ArticleExtractor.INSTANCE.getText(url);在JRuby中试过这个:require'java'url=java.net.URL.new("http://www

  9. java - 我的模型类或其他类中应该有逻辑吗 - 2

    我只想对我一直在思考的这个问题有其他意见，例如我有classuser_controller和classuserclassUserattr_accessor:name,:usernameendclassUserController//dosomethingaboutanythingaboutusersend问题是我的User类中是否应该有逻辑user=User.newuser.do_something(user1)oritshouldbeuser_controller=UserController.newuser_controller.do_something(user1,user2)我

  10. java - 什么相当于 ruby​​ 的 rack 或 python 的 Java wsgi？ - 2

    什么是ruby​​的rack或python的Java的wsgi？还有一个路由库。 最佳答案 来自Python标准PEP333:Bycontrast,althoughJavahasjustasmanywebapplicationframeworksavailable,Java's"servlet"APImakesitpossibleforapplicationswrittenwithanyJavawebapplicationframeworktoruninanywebserverthatsupportstheservletAPI.ht

随机推荐