不兼容的魔法值错误

时间：2011-06-13 08:04:45

标签： java classloader magic-numbers

我正在关注以下链接中的示例：

http://www.javaworld.com/javaworld/jw-10-1996/jw-10-indepth.html?page=1 这是我得到的输出：

This program will use SimpleClassLoader.
        >>>>>> Load class : TestClass
        >>>>>> Not a system class.
        >>>>>> Fetching the implementation of TestClass
file was read successfully
Exception in thread "main" java.lang.ClassFormatError: Incompatible magic value 1768779887 in class file 
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at aha.SimpleClassLoader.loadClass(SimpleClassLoader.java:80)
    at aha.SimpleClassLoader.loadClass(SimpleClassLoader.java:42)
    at aha.Example.main(Example.java:11)

这是我读取文件的方法示例：

 private byte getClassImplFromDataBase(String className)[] {
        System.out.println("        >>>>>> Fetching the implementation of "+className);
        byte result[];
        try {
            FileInputStream fi = new FileInputStream("C:/delete/"+className+".impl");
            result = new byte[fi.available()];
            fi.read(result);
            System.out.println("file was read succesfullyl");
            return result;
        } catch (Exception e) {

            /*
             * If we caught an exception, either the class wasnt found or it
             * was unreadable by our process.
             */
            return null;
        }
    }

我将TestClass.impl文件放在C：/ delete目录下。 我的课程位于包下：aha 因此，文件TestClass.impl被读取正常，但在此期间发生了一些事情   result = defineClass（classData，0，classData.length）; 我知道这个方法已被弃用但仍然是??

2 个答案:

答案 0 :(得分：5)

我不知道文件类型.impl是什么，但我怀疑它不是包含字节代码的类文件。十六进制中的幻数1768779887是ASCII中的696D706F或impo。 （我怀疑import的前四个字节）

所以在我看来你正在尝试加载你不能做的未编译的Java代码（这就是编译器的用途）你最好使用编译器API，但我怀疑你确实需要类似OSGi的东西。试图加载你自己的课程要求你对课程加载的工作方式有一个非常详细的了解。

答案 1 :(得分：1)

我在常规struts2项目中遇到了类似的错误，解决了清理项目的问题。

8266 ERROR [main]: Excepción arrancando filtro struts2
java.lang.ClassFormatError: Incompatible magic value 0 in class file com/lm/action/musician/MusicianList
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1650)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:856)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1305)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1187)
    at com.opensymphony.xwork2.util.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:144)
    at com.opensymphony.xwork2.ObjectFactory.getClassInstance(ObjectFactory.java:108)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:424)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:378)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:495)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:286)
    at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:112)
    at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:234)
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
    at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:390)
    at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:437)
    at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:225)
    at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:308)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:79)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3563)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4133)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1012)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1012)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
    at org.apache.catalina.core.StandardService.start(StandardService.java:450)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:680)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:536)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:275)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
8266 ERROR [main]: Excepción arrancando filtro struts2
java.lang.ClassFormatError: Incompatible magic value 0 in class file com/lm/action/musician/MusicianList
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1650)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:856)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1305)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1187)
    at com.opensymphony.xwork2.util.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:144)
    at com.opensymphony.xwork2.ObjectFactory.getClassInstance(ObjectFactory.java:108)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:424)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:378)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:495)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:286)
    at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:112)
    at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:234)
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
    at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:390)
    at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:437)
    at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:225)
    at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:308)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:79)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3563)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4133)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1012)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1012)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
    at org.apache.catalina.core.StandardService.start(StandardService.java:450)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:680)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:536)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:275)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
abr 19, 2013 10:32:25 AM org.apache.catalina.core.StandardContext start
SEVERE: Error filterStart
abr 19, 2013 10:32:25 AM org.apache.catalina.core.StandardContext start
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