我有下一个代码：
File root = new File("./build/classes");
URLClassLoader classLoader = URLClassLoader.newInstance(new URL[] { root.toURI().toURL() });
Class<?> loadedClass = Class.forName("events.Source", true,classLoader);
// JSON --> Java "Get the actual type"
Type listType = new DefaultParameterizedType(ArrayList.class, loadedClass);
Gson gson = new Gson();
ArrayList<loadedClass> resourcesList = gson.fromJson(jsonString, listType);
当我运行程序时，它显示错误 java.lang.ClassNotFoundException：org.apache.commons.lang.builder.ToStringBuilder 我有 commons-lang3-3.4.jar < / strong>我的 WEB-INF 中的文件 - ＆gt; lib 目录，当我调用此声明时，我不知道为什么会显示此错误：
System.out.println("Sending" + resourcesList.get(i).toString());
控制台输出是：
jun 11, 2015 11:31:32 AM com.sun.jersey.spi.container.ContainerResponse mapMappableContainerException
GRAVE: The exception contained within MappableContainerException could not be mapped to a response, re-throwing to the HTTP container
java.lang.NoClassDefFoundError: org/apache/commons/lang/builder/ToStringBuilder
at eventos.Posicion.toString(Unknown Source)
at eventos.ParserFromFile.parsearListaRecursosDesdeFichero(ParserFromFile.java:132)
at eventos.Analisis.faseDos(Analisis.java:126)
at resources.ConfiguracionResource.addObjetoJSON(ConfiguracionResource.java:213)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302)
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:733)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.builder.ToStringBuilder
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.net.FactoryURLClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 45 more
jun 11, 2015 11:31:32 AM org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: El Servlet.service() para el servlet [Jersey REST Service] en el contexto con ruta [/EasyCEP] lanzó la excepción [java.lang.NoClassDefFoundError: org/apache/commons/lang/builder/ToStringBuilder] con causa raíz
java.lang.ClassNotFoundException: org.apache.commons.lang.builder.ToStringBuilder
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.net.FactoryURLClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at eventos.Posicion.toString(Unknown Source)
at eventos.ParserFromFile.parsearListaRecursosDesdeFichero(ParserFromFile.java:132)
at eventos.Analisis.faseDos(Analisis.java:126)
at resources.ConfiguracionResource.addObjetoJSON(ConfiguracionResource.java:213)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302)
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:733)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
答案 0 :(得分：3)
从API看来，你应该在3.3版本中导入org.apache.commons。 lang3 .builder.ToStringBuilder而不是org.apache.commons。 lang 。 builder.ToStringBuilder
所以我猜你用以前的版本（2？）编译commons-lang并在你的网络服务器中使用更新版本。
https://commons.apache.org/proper/commons-lang/javadocs/api-2.3/
https://commons.apache.org/proper/commons-lang/javadocs/api-3.3/
答案 1 :(得分：0)
// We change the classpath, adding a new jar to the ClassLoader.(org.apache.commons.lang.builder.ToStringBuilder)
try {
// We get the ClassLoader and their method addURL()
URLClassLoader classLoader = ((URLClassLoader) ClassLoader
.getSystemClassLoader());
Method metodoAdd = URLClassLoader.class.getDeclaredMethod("addURL",
new Class[] { URL.class });
metodoAdd.setAccessible(true);
// The URL of the jar we want to add
URL url = new URL(
"file:///C:/Users/****/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/*****/WEB-INF/lib/commons-lang-2.6.jar");
// the method addURL is invoked passing that jar´s url
metodoAdd.invoke(classLoader, new Object[] { url });
} catch (Exception e) {
e.printStackTrace();
}