java - Jetty启动不加载WEB-INF/lib下的JAR

问题描述

问 题

Jetty启动不加载WEB-INF/lib下的JAR

直接使用java启动下面的main函数，发现Jetty没有到WEB-INF/lib下面的JAR。代码如下：

/**
 * 启动器
 */
public class Launcher {
    public static void main(String args[]) throws Exception {
        new Launcher().start();
    }

    void start() throws Exception {
        // 服务器的监听端口
        Server server = new Server(80);
        // 关联一个已经存在的上下文
        WebAppContext context = new WebAppContext();
        // 设置描述符位置
        String path = Launcher.class.getResource("/").getPath();
        context.setDescriptor(path + "../web.xml");
        // 设置Web内容上下文路径
        context.setResourceBase(path + "/../../");
        // 设置上下文路径
        context.setContextPath("/admin/");
        context.setParentLoaderPriority(true);
        //开启HTML，CSS，JS热部署
        context.setInitParameter("org.eclipse.jetty.servlet.Default.useFileMappedBuffer", "false");
        server.setHandler(context);
        // 启动
        server.start();
        server.join();
    }
}

错误日志：

2016-06-05 17:01:13.080 [main] ERROR o.s.web.servlet.DispatcherServlet - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'addressConsigneeIo' defined in file [D:\Project\CORP\EP\netease-ep\trunk\WebContent\WEB-INF\classes\org\darkgem\io\address\AddressConsigneeIo.class]: Post-processing failed of bean type [class org.darkgem.io.address.AddressConsigneeIo] failed; nested exception is java.lang.IllegalStateException: Failed to introspect bean class [org.darkgem.io.address.AddressConsigneeIo] for resource metadata: could not find class that it depends on
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:940)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:518)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:667)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:633)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:681)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:552)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:493)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
    at javax.servlet.GenericServlet.init(GenericServlet.java:244)
    at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:640)
    at org.eclipse.jetty.servlet.ServletHolder.initialize(ServletHolder.java:419)
    at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:875)
    at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:348)
    at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1379)
    at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1341)
    at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:774)
    at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:261)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:517)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
    at org.eclipse.jetty.server.Server.start(Server.java:405)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
    at org.eclipse.jetty.server.Server.doStart(Server.java:372)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.darkgem.jetty.Launcher.start(Launcher.java:31)
    at org.darkgem.jetty.Launcher.main(Launcher.java:11)
Caused by: java.lang.IllegalStateException: Failed to introspect bean class [org.darkgem.io.address.AddressConsigneeIo] for resource metadata: could not find class that it depends on
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.findResourceMetadata(CommonAnnotationBeanPostProcessor.java:334)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(CommonAnnotationBeanPostProcessor.java:287)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:935)
    ... 34 common frames omitted
Caused by: java.lang.NoClassDefFoundError: Lorg/springframework/jdbc/core/JdbcTemplate;
    at java.lang.Class.getDeclaredFields0(Native Method)
    at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
    at java.lang.Class.getDeclaredFields(Class.java:1916)
    at org.springframework.util.ReflectionUtils.getDeclaredFields(ReflectionUtils.java:710)
    at org.springframework.util.ReflectionUtils.doWithLocalFields(ReflectionUtils.java:652)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.buildResourceMetadata(CommonAnnotationBeanPostProcessor.java:351)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.findResourceMetadata(CommonAnnotationBeanPostProcessor.java:330)
    ... 36 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.jdbc.core.JdbcTemplate
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 43 common frames omitted

解决方案

启动的时候，使用 java -cp jetty.jar;WebContent\WEB-INF\classes Launcher 启动项目。

从错误日志可以看出是因为找不到 org.springframework.core.JdbcTemplate 这个类。而发生的问题的源码位于 classes 下面的业务代码中。

所以形成了一个：

AppClassloader(业务代码，依赖spring.jar)
      |
WebAppClssLoader(WEB-INF\lib\spring.jar)

这样子的依赖结构，所以在初始化Spring 容器的时候，初始化一个AppCloassLoader中的类（依赖Spring）发现无法查询到JdbcTemplate这个Spring类。这是因为加载器的双亲委托机制。

解决方法：

1. 启动的时候指定所有的lib和jar

2. 或者强制指定，不使用启动jetty Launcher加载的classpath： context.setParentLoaderPriority(false);

3. 使用一个 start.jar这种封装好的jetty启动器来启动，启动的时候，还是需要指定具体的classpath

package org.darkgem.jetty;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.webapp.WebAppContext;

import java.io.File;
import java.io.FilenameFilter;

/**
 * 启动器
 */
public class Launcher {
    public static void main(String args[]) throws Exception {
        if (args.length == 0) {
            System.err.println("no web-app path");
            return;
        }
        String path = args[0];
        // 服务器的监听端口
        Server server = new Server(80);
        // 关联一个已经存在的上下文
        WebAppContext context = new WebAppContext();
        context.setDescriptor(path + "/WEB-INF/web.xml");
        // 设置Web内容上下文路径
        context.setResourceBase(path);
        // 设置上下文路径
        context.setContextPath("/admin/");
        context.setParentLoaderPriority(true);
        {
            StringBuilder sb = new StringBuilder();
            {
                sb.append(path);
                sb.append("/WEB-INF/classes");
                sb.append(";");
            }
            {
                File libDir = new File(path + "/WEB-INF/lib");
                if (libDir.exists() && libDir.isDirectory()) {
                    for (File jar : libDir.listFiles(new FilenameFilter() {
                        @Override
                        public boolean accept(File dir, String name) {
                            if (name.endsWith(".zip") || name.endsWith(".jar")) {
                                return true;
                            }
                            return false;
                        }
                    })) {
                        sb.append(jar.getAbsolutePath());
                        sb.append(";");
                    }
                }
            }
            System.out.println(sb.toString());
            context.setExtraClasspath(sb.toString());
        }
        //开启HTML，CSS，JS热部署
        context.setInitParameter("org.eclipse.jetty.servlet.Default.useFileMappedBuffer", "false");
        server.setHandler(context);
        // 启动
        server.start();
        server.join();
    }
}

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