Java URLClassLoader未加载jar文件
我目前正在开发一个web应用程序，它必须从本地驱动器上的目录加载jar文件。 经过一番研究后，Java URLClassLoader未加载jar文件,java,Java,我目前正在开发一个web应用程序，它必须从本地驱动器上的目录加载jar文件。 经过一番研究后，URLClassLoaders似乎是最合适的解决方案 牛肉： public @Slf4j class ActionLoader { private static void addFilesToClassPath(File path) { URLClassLoader clazzLoader = null; try { clazzLoader = n
URLClassLoaderspublic @Slf4j class ActionLoader {
private static void addFilesToClassPath(File path) {
URLClassLoader clazzLoader = null;
try {
clazzLoader = new URLClassLoader(new URL[] {path.toURI().toURL()},
ActionLoader.class.getClassLoader());
try {
Class.forName("de.befoe.xyz.ActionTest", false, clazzLoader);
} catch (ClassNotFoundException e) {
log.error("Class not found", e);
}
try {
clazzLoader.loadClass("de.befoe.xyz.ActionTest");
} catch (ClassNotFoundException e) {
log.error("Class not found", e);
}
} catch (SecurityException e) {
log.error("Access denied", e);
} catch (MalformedURLException e) {
log.error("Malformed URL", e);
} finally {
if (clazzLoader != null) {
try {
clazzLoader.close();
} catch (IOException e) {
log.error("Error closing the class loader", e);
}
}
}
}
}
ClassNotFoundExceptionjava.lang.ClassNotFoundException: de.befoe.xyz.ActionTest
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at de.procrm.speedindexer.scr.ActionLoader.addFilesToClassPath(ActionLoader.java:80)
at de.procrm.speedindexer.scr.ActionLoader.loadActions(ActionLoader.java:31)
at de.procrm.speedindexer.scr.Init.contextInitialized(Init.java:39)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4842)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5303)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:940)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:467)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1612)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.manager.ManagerServlet.check(ManagerServlet.java:1451)
at org.apache.catalina.manager.ManagerServlet.deploy(ManagerServlet.java:724)
at org.apache.catalina.manager.ManagerServlet.doPut(ManagerServlet.java:423)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:651)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1099)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
java.lang.ClassNotFoundException: de.befoe.xyz.ActionTest
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at de.procrm.speedindexer.scr.ActionLoader.addFilesToClassPath(ActionLoader.java:81)
at de.procrm.speedindexer.scr.ActionLoader.loadActions(ActionLoader.java:31)
at de.procrm.speedindexer.scr.Init.contextInitialized(Init.java:39)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4842)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5303)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:940)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:467)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1612)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.manager.ManagerServlet.check(ManagerServlet.java:1451)
at org.apache.catalina.manager.ManagerServlet.deploy(ManagerServlet.java:724)
at org.apache.catalina.manager.ManagerServlet.doPut(ManagerServlet.java:423)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:651)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1099)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
ClassNotFoundExceptionjava.lang.ClassNotFoundException: de.befoe.xyz.ActionTest
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at de.procrm.speedindexer.scr.ActionLoader.addFilesToClassPath(ActionLoader.java:80)
at de.procrm.speedindexer.scr.ActionLoader.loadActions(ActionLoader.java:31)
at de.procrm.speedindexer.scr.Init.contextInitialized(Init.java:39)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4842)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5303)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:940)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:467)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1612)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.manager.ManagerServlet.check(ManagerServlet.java:1451)
at org.apache.catalina.manager.ManagerServlet.deploy(ManagerServlet.java:724)
at org.apache.catalina.manager.ManagerServlet.doPut(ManagerServlet.java:423)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:651)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1099)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
java.lang.ClassNotFoundException: de.befoe.xyz.ActionTest
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at de.procrm.speedindexer.scr.ActionLoader.addFilesToClassPath(ActionLoader.java:81)
at de.procrm.speedindexer.scr.ActionLoader.loadActions(ActionLoader.java:31)
at de.procrm.speedindexer.scr.Init.contextInitialized(Init.java:39)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4842)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5303)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:940)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:467)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1612)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.manager.ManagerServlet.check(ManagerServlet.java:1451)
at org.apache.catalina.manager.ManagerServlet.deploy(ManagerServlet.java:724)
at org.apache.catalina.manager.ManagerServlet.doPut(ManagerServlet.java:423)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:651)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:614)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1099)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
ClassNotFoundException现在的问题是为什么没有正确使用父类装入器类。经过进一步研究，我调用ActionLoader.class.getClassLoader（）使用的父类加载器似乎不是正确的。因此，在eclipse调试器中，我看到一个名为delegate的字段被设置为false。因此，我改为使用这个类加载器父级，并且文件加载很好。我没有您的JAR文件，因此我已经在自定义路径上使用我的一个JAR文件进行了测试，并且使用systemClassLoader正确加载了类 以下是示例代码：
addFilesToClassPath(new File("C:/Users/Domenico/.m2/repository/com/doctorchat/core/0.1.ALPHA/core-0.1.ALPHA.jar"));
private static void addFilesToClassPath(File path) {
try(URLClassLoader clazzLoader = new URLClassLoader(new URL[]{path.toURI().toURL()}, ClassLoader.getSystemClassLoader())) {
Class c = clazzLoader.loadClass("com.doctorchat.core.exceptions.NotImplementedException");
System.out.println(c);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// clazzLoader.getResource()
}
你确定这个类真的在罐子里吗？使用命令行中的
JAR tf myJar.JAR/clazloader.close（）;调用，因为您不太可能已经使用了刚刚加载的类。为了避免不可避免的后续问题…我更改了代码，使URLClassLoader列表使用直接指向文件的URL进行初始化，但它仍然不起作用。移除clazzLoader.close（）仍然没有改变任何东西（正如我预期的那样，正如后来调用的那样）。两个使用过的jar文件都很好。我用“jar tf”-命令检查了这两个类，所有的类文件都在那里。如果您仍然有ClassNotFoundException
s，请检查堆栈跟踪中是否有引起的。另外，使用getURLs（）
打印URL并检查这些URL是否确实可以从应用程序中访问也是值得的。成功的原因不是因为系统类加载器，而是因为您提供了一个直接指向jar的URL，而不是指向包含它的目录。@realpoint如上所述，改变这个，没用。使用Domenicos方法也不起作用，类装入器的类和包仍然是空的。