urlclassloader

【java.lang.UnsupportedClassVersionError】版本不一致出错

由 巧了我就是萌 提交于 2019-12-28 16:23:02
这种错误的全部报错信息： 1 java.lang.UnsupportedClassVersionError: org/apache/lucene/store/Directory : Unsupported major.minor version 51.0 2 at java.lang.ClassLoader.defineClass1(Native Method) 3 at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) 4 at java.lang.ClassLoader.defineClass(ClassLoader.java:615) 5 at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) 6 at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) 7 at java.net.URLClassLoader.access$000(URLClassLoader.java:58) 8 at java.net.URLClassLoader$1.run(URLClassLoader.java:197) 9 at java.security

java static initializer called twice

由 ☆樱花仙子☆ 提交于 2019-12-25 05:46:09
问题 static boolean isClassLoaded(String fullname) { try { Class.forName(fullname, false, Loader.instance().getModClassLoader()); return true; } catch (Exception e) { return false; } } does this method has potential to trigger fullname's static initializer ? i have problem with static initializer called twice. when i try to check if class loaded using isClassLoaded and try to use that class, i get error because of constructor called twice. anyone know what is problem with Class.forName(fullname,

Custom URLClassLoader, NoClassDefFoundError when run

由 匆匆过客 提交于 2019-12-20 02:44:28
问题 I've created my own URLClassLoader , and set it as the system classloader via java.system.class.loader . It's initialized and everything, but the classes I'm trying to load aren't found. Here's the URLClassLoader : public class LibraryLoader extends URLClassLoader { public LibraryLoader(ClassLoader classLoader) { super(new URL[0], classLoader); } synchronized public void addJarToClasspath(String jarName) throws MalformedURLException, ClassNotFoundException { File filePath = new File(jarName);

java.lang.ClassNotFoundException与java.lang.NoClassDefFoundError的区别

由 我与影子孤独终老i 提交于 2019-12-19 17:12:08
　　以前一直没有注意过这个问题，前两天机缘巧合上网查了一下，然后自己测试验证了一下。 虽然网上说法很多，但是关于NoClassDefFoundError并没有给出一个样例，所以一直无法理解，索性自己验证了一下， 收获还不少。 　　ClassNotFoundException 　　ClassNotFoundException这个错误，比较常见也好理解。 　　 原因：就是找不到指定的class。 　　常见的场景就是： 　　1 调用class的forName方法时，找不到指定的类 　　2 ClassLoader 中的 findSystemClass() 方法时，找不到指定的类 　　3 ClassLoader 中的 loadClass() 方法时，找不到指定的类 　　开发者平时会有这样一种使用方法，类似JDBC加载驱动！ 1 package test321; 2 3 public class test { 4 public static void main(String[] args) { 5 try { 6 Class.forName("test321.hello"); 7 } catch (ClassNotFoundException e) { 8 e.printStackTrace(); 9 } 10 } 11 } 　　此时，程序会到当前的目录中寻找指定位置test321

Java 9, compatability issue with ClassLoader.getSystemClassLoader

由 血红的双手。 提交于 2019-12-17 09:51:36
问题 The following code adds jar file to the build path, it works fine with Java 8. However, it throws exception with Java 9, the exception is related to the cast to URLClassLoader. Any ideas how this can be solved? an optimal solution will edit it to work with both Java 8 & 9. private static int AddtoBuildPath(File f) { try { URI u = f.toURI(); URLClassLoader urlClassLoader = (URLClassLoader) ClassLoader.getSystemClassLoader(); Class<URLClassLoader> urlClass = URLClassLoader.class; Method method

Provider not a subtype inside docker container

由 只谈情不闲聊 提交于 2019-12-14 02:32:53
问题 Situation I'm developing an application that uses Java's URLClassLoader and ServiceLoader to load jar files. Inside these jar files is the provider that implements my interface. The folder structure is as described in this post by oracle meaning that: The interface is in the same directory as the class that implements the interface in the plugin (com.x.projectname.plugin.IInterface.java). In the plugin, both the interface and the class that implements it are in the com.x.projectname.plugin

NoClassDefFoundError when dynamically adding jar files at runtime

由 若如初见. 提交于 2019-12-13 00:48:37
问题 UPDATE: I think the issue may be caused by the fact that the TestFramework.jar depends on JUnit and somehow is not finding the junit jar when it (TestFramework) loads. Still not sure on a solution, if I'm right I need a way to specify the order in which jars are loaded. First here is some background on what I'm doing: I'm trying to create a tool that will allow users to specify a java source file which is an extension of a JUnit TestCase and contains test data in a method named getTestData.

Java How to load classes out of a jar in the classpath with the System ClassLoader (no URLClassLoader)?

由 回眸只為那壹抹淺笑 提交于 2019-12-12 03:15:45
问题 So, I need to load some class at runtime with the System ClassLoader out of a jar in the classpath, but every time I try, I get a ClassNotFoundException. With the System ClassLoader, am I able to do just: x.y.classineed (x and y being packages) or would I have to do something like: pathtox.x.y.classineed, assuming it's even possible to do this? 回答1: The JAR must not be in your CLASSPATH. This works fine: I have the JDOM JAR in my CLASSPATH. package cruft; /** * ClassLoaderDemo * @author

No such field exception while loading “scl” field from Classloader

由 时光怂恿深爱的人放手 提交于 2019-12-11 19:13:28
问题 I am moving my code from JDK 8 to Open JDK 12. While doing so, I am facing following issue : java.lang.NoSuchFieldException: scl while trying to call ClassLoader.class.getDeclaredField("scl"). This was working fine in Java 8 but no longer works in newer Java versions. I did some findings and believe it has got to do with the way working of reflection and use of internal Java packages have changed since Java 8. Set<URL> classLoaderUrls = computeClassLoaderUrls(); ClassLoader

understanding urlclassloader, how to access a loaded jar's classes

由 江枫思渺然 提交于 2019-12-11 19:09:13
问题 I am trying to understand how to access/make available a jar file using URLClassLoader. Firstly I am loading the jar file with package myA; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.net.MalformedURLException; import java.net.URL; import java.net.URLClassLoader; import org.jgroups.JChannel; public class loader { JChannel channel; String user_name=System.getProperty("user.name", "n/a"); private void start()
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