我有这样的代码片段:

@RunWith(PowerMockRunner.class)
@PrepareForTest({Thread.class})
public class AllMeasuresDataTest {

@Before
public void setUp() throws Exception {
}

@Test
public void testGetMeasures() {
    AllMeasuresData measure = new AllMeasuresData();
    assertEquals(measure.getMeasures(), null);
    HashMap<String, Measure> map = new HashMap<String, Measure>();
    measure.setMeasures(map);
    assertEquals(measure.getMeasures(), map);
    measure.setMeasures(null);
    assertEquals(measure.getMeasures(), null);
}

@Test
public void testAllMeasuresData() throws IOException {
    ClassLoader loader = PowerMockito.mock(ClassLoader.class);
    Thread threadMock = PowerMockito.mock(Thread.class);
    Vector<URL> vec = new Vector<URL>();
    Mockito.when(loader.getResources("measure")).thenReturn(vec.elements());
    Mockito.when(threadMock.getContextClassLoader()).thenReturn(loader);
    PowerMockito.mockStatic(Thread.class);
    Mockito.when(Thread.currentThread()).thenReturn(threadMock);
        ...
    }
}

在运行此测试时,我得到了:

java.lang.LinkageError: loader constraint violation: loader (instance of org/powermock/core/classloader/MockClassLoader) previously initiated loading …

我开发了一个基于XML的大量Java应用程序,最近在Ubuntu Linux上遇到了一个有趣的问题.

我的应用程序使用Java插件框架,似乎无法将dom4j创建的XML文档转换为Batik的 SVG规范实现.

在控制台上,我了解到发生了错误:

Exception in thread "AWT-EventQueue-0" java.lang.LinkageError: loader constraint violation in interface itable initialization: when resolving method "org.apache.batik.dom.svg.SVGOMDocument.createAttribute(Ljava/lang/String;)Lorg/w3c/dom/Attr;" the class loader (instance of org/java/plugin/standard/StandardPluginClassLoader) of the current class, org/apache/batik/dom/svg/SVGOMDocument, and the class loader (instance of <bootloader>) for interface org/w3c/dom/Document have different Class objects for the type org/w3c/dom/Attr used in the signature
    at org.apache.batik.dom.svg.SVGDOMImplementation.createDocument(SVGDOMImplementation.java:149)
    at org.dom4j.io.DOMWriter.createDomDocument(DOMWriter.java:361)
    at org.dom4j.io.DOMWriter.write(DOMWriter.java:138)

我认为问题是由JVM的原始类加载器与插件框架部署的类加载器之间的冲突引起的.

据我所知,不可能为框架指定要使用的类加载器.它可能是破解它,但我宁愿采用一种不那么积极的方法来解决这个问题,因为(无论出于什么原因)它只发生在Linux系统上.

你们其中一个遇到过这样的问题,并且知道如何解决这个问题或至少解决问题的核心问题？

当我尝试在Tomcat 7上运行我的webapp时,我得到以下异常:

exception

javax.servlet.ServletException: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;
" the class loader (instance of org/apache/jasper/servlet/JasperLoader) of the current class, org/apache/jsp/index_jsp, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, 
have different Class objects for the type javax/el/ExpressionFactory used in the signature
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:343)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

root cause

java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/jasper/servlet/JasperLoader) of the current class, org/apache/jsp/index_jsp, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for …

这是我的Java环境：

~: java -version
    java version "11.0.1" 2018-10-16 LTS
    Java(TM) SE Runtime Environment 18.9 (build 11.0.1+13-LTS)
    Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.1+13-LTS, mixed mode)

但是，当编译后尝试执行程序时，出现以下错误：

Error: LinkageError occurred while loading main class ClassName
    java.lang.UnsupportedClassVersionError: ClassName has been 
    compiled by a more recent version of the Java Runtime 
    (class file version 55.0), this version of the Java Runtime 
    only recognizes class file versions up to 54.0

我的 PATH 和 JAVA_HOME 变量都指向这个版本的 java。我下载了其他版本，但似乎它们没有在系统中注册：

update-alternatives --display java
java - auto mode …

JSF Web应用程序尝试从Java EE Web服务检索资源.JSF Web应用程序运行正常.自从我将Http客户端源添加到反向Web服务资源以来,JBoss实例声称:

15:29:47,689 SEVERE [javax.enterprise.resource.webcontainer.jsf.application] (http--0.0.0.0-443-1) Error Rendering View[/index.xhtml]: javax.el.ELException: /surfaceParts/sideBarLeft.xhtml @14,79 value="#{categories.cats}": java.lang.LinkageError: loader constraint violation: when resolving method "org.jboss.resteasy.client.core.executors.ApacheHttpClient4Executor.<init>(Lorg/apache/http/client/HttpClient;Lorg/apache/http/protocol/HttpContext;)V" the class loader (instance of org/jboss/modules/ModuleClassLoader) of the current class, at/fhj/ase/ssl/SSLClientHelper, and the class loader (instance of org/jboss/modules/ModuleClassLoader) for resolved class, org/jboss/resteasy/client/core/executors/ApacheHttpClient4Executor, have different Class objects for the type xecutors.ApacheHttpClient4Executor.<init>(Lorg/apache/http/client/HttpClient;Lorg/apache/http/protocol/HttpContext;)V used in the signature
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114) [jsf-impl-2.1.7-jbossorg-2.jar:]
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
    at javax.faces.component.UIData.getValue(UIData.java:731) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
    at javax.faces.component.UIData.getDataModel(UIData.java:1798) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
    at javax.faces.component.UIData.setRowIndexWithoutRowStatePreserved(UIData.java:484) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
    at javax.faces.component.UIData.setRowIndex(UIData.java:473) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
    at …

我有一个工作代码，它动态加载具有不同类名的不同类实现。类文件被加载到内存数据库( Apache Derby Db ) 中，并且类加载器从BLOB列中检索.class文件。

Exception in thread "main" java.lang.LinkageError: loader (instance of  com/levent/classloader/DerbyServerClassLoader): attempted  duplicate class definition for name: "com/levent/greeter/Greeter"
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at com.levent.classloader.DerbyServerClassLoader.findClass(DerbyServerClassLoader.java:38)
    at com.levent.example.ClientClassLoaderDBVersionDemo.main(ClientClassLoaderDBVersionDemo.java:43)

package com.levent.classloader;

import java.sql.Blob; …