9

我正在使用NetBeans，而Tomcat似乎在.war应用程序中部署了两次，两次启动了 Web 应用程序。

我已经尝试过 Tomcat 6 和 7 并且结果相同。

我有一个 Spring MVC、Hibernate 和 Thymeleaf 应用程序。META-INF下的Context.xml内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/website"/>

这是日志。

**First deployment starts**

[ INFO] 07:13:09 ContextLoader - Root WebApplicationContext: initialization started
[ INFO] 07:13:09 XmlWebApplicationContext - Refreshing Root WebApplicationContext:     startup date [Thu May 23 07:13:09 EST 2013]; root of context hierarchy
2013-05-23 07:13:10 JRebel: Monitoring Spring bean definitions in     '/Users/pack/NetBeansProjects/mysite/site/src/main/webapp/WEB-INF/applicationContext-  data.xml'.
[ INFO] 07:13:10 XmlBeanDefinitionReader - Loading XML bean definitions from     ServletContext resource [/WEB-INF/applicationContext-data.xml]
[ INFO] 07:13:10 ClassPathScanningCandidateComponentProvider - JSR-330 'javax.inject.Named' annotation found and supported for component scanning
            ***(tomcat initializes hibernate and other spring beans)***
                                      ...
May 23, 2013 7:13:17 AM org.apache.catalina.startup.Catalina start
INFO: Server startup in 15552 ms
                                 ***Tomcat started***
                      ***Tomcat tries to shut down the context***

[ INFO] 07:13:18 XmlWebApplicationContext - Closing WebApplicationContext for namespace     'spring-mvc-servlet': startup date [Thu May 23 07:13:15 EST 2013]; parent: Root WebApplicationContext
[ INFO] 07:13:18 DefaultListableBeanFactory - Destroying singletons in  org.springframework.beans.factory.support.DefaultListableBeanFactory@5bbe2de2: defining beans    [blHeadProcessor,blHeadProcessorExtensionManager,navigationProcessor,blPaginationPageLinkPro cessor,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,blRegisterCustomerValidator,blCategoryController,com.package.ui.thymeleaf.CategoryHandlerMapping#0,templateResolver,templateEngine,org.thymeleaf.spring3.view.ThymeleafViewResolver#0,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor]; parent:   org.springframework.beans.factory.support.DefaultListableBeanFactory@521e7f21
[ INFO] 07:13:18 XmlWebApplicationContext - Closing Root WebApplicationContext: startup  date [Thu May 23 07:13:09 EST 2013]; root of context hierarchy 
[ INFO] 07:13:18 DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@521e7f21: defining beans    [org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,org.springframework.context.support.PropertySourcesPlaceholderConfigurer#0,blCategoryDao,blCustomerDao,blIdGenerationDao,nlpDao,jpaTemplate,webDS,entityManagerFactory,transactionManager,org.springframework.security.filterChains,org.springframework.security.filterChainProxy,org.springframework.security.web.DefaultSecurityFilterChain#0,org.springframework.security.web.DefaultSecurityFilterChain#1,org.springframework.security.web.DefaultSecurityFilterChain#2,org.springframework.security.web.DefaultSecurityFilterChain#3,org.springframework.security.web.DefaultSecurityFilterChain#4,org.springframework.security.web.DefaultSecurityFilterChain#5,org.springframework.security.web.PortMapperImpl#0,org.springframework.security.web.PortResolverImpl#0,org.springframework.security.authentication.ProviderManager#0,org.springframework.security.web.context.HttpSessionSecurityContextRepository#0,org.springframework.security.web.savedrequest.HttpSessionRequestCache#0,org.springframework.security.web.access.channel.ChannelDecisionManagerImpl#0,org.springframework.security.access.vote.AffirmativeBased#0,org.springframework.security.web.access.intercept.FilterSecurityInterceptor#0,org.springframework.security.web.access.DefaultWebInvocationPrivilegeEvaluator#0,org.springframework.security.authentication.AnonymousAuthenticationProvider#0,org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter#0,org.springframework.security.userDetailsServiceFactory,org.springframework.security.web.DefaultSecurityFilterChain#6,org.springframework.security.authentication.dao.DaoAuthenticationProvider#0,org.springframework.security.authentication.DefaultAuthenticationEventPublisher#0,org.springframework.security.authenticationManager,blUserDetailsService,blCatalogService,blCustomerService,entityService,fbPageService,blIdGenerationService,blLoginService,nlpService,priceIncreaseValidator,searchFacetService,blEntityConfiguration,blPasswordEncoder,solrIndexService,solrEmbedded,textEncryptor,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor]; root of factory hierarchy
[ INFO] 07:13:18 LocalContainerEntityManagerFactoryBean - Closing JPA EntityManagerFactory for persistence unit 'blPU'
[ INFO] 07:13:18 SessionFactoryImpl - closing
May 23, 2013 7:13:18 AM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
SEVERE: The web application [/website] registered the JDBC driver    [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To   prevent a memory leak, the JDBC Driver has been forcibly unregistered.
May 23, 2013 7:13:19 AM org.apache.catalina.startup.HostConfig deleteRedeployResources
INFO: Undeploying context [/website]
May 23, 2013 7:13:19 AM org.apache.catalina.startup.HostConfig deployDescriptor
INFO: Deploying configuration descriptor /Users/pack/Servers/apache-tomcat- 7.0.34/conf/Catalina/localhost/website.xml
2013-05-23 07:13:23 JRebel: Monitoring Log4j configuration in   'file:/Users/pack/NetBeansProjects/mysite/site/target/mycompany/WEB-INF/classes/log4j.xml'.

                          ***Tomcat tries to restart again***

[ INFO] 07:13:23 ContextLoader - Root WebApplicationContext: initialization started
[ INFO] 07:13:23 XmlWebApplicationContext - Refreshing Root WebApplicationContext:   startup date [Thu May 23 07:13:23 EST 2013]; root of context hierarchy
2013-05-23 07:13:24 JRebel: Monitoring Spring bean definitions in   '/Users/pack/NetBeansProjects/mysite/site/src/main/webapp/WEB-INF/applicationContext-  data.xml'.
[ INFO] 07:13:24 XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/applicationContext-data.xml]

并成功启动。

我不明白的是，Tomcat 为什么要部署应用程序两次。这不会在我第一次在新的 tomcat 实例上部署应用程序时发生，因为 website.xml 文件尚未在 tomcats /conf/catalina/localhost 文件夹中。但是当我再次从 netbeans 停止并运行 tomcat 时，website.xml 文件仍在 /conf/catalina/localhost 文件夹中，但在第二次部署即将发生之前被删除并重新部署。

我尝试autoDeploy在 Tomcat 的 server.xml 文件中设置为 false，但没有帮助。

<Host name="localhost"  appBase="webapps"
        unpackWARs="true" autoDeploy="false">

可能是 Tomcat 应该在每次 Tomcat 停止时删除 /conf/catalina/localhost 文件夹下的 website.xml 文件。

这就是 localhost 文件夹下的 website.xml 文件的样子

<?xml version="1.0" encoding="UTF-8"?>
<Context
    docBase="/Users/pack/NetBeansProjects/mysite/site/target/mycompany"  
    path="/website"
/>
4

4 回答 4

9

我发现删除文件 conf/localhost/myappname.xml 会阻止应用程序初始化两次。基本上 Tomcat 正在重新启动，并重新启动您的应用程序的旧版本。然后在 Netbeans 部署它时再次启动。作为一种解决方法，我在 ContextListener contextDestroyed() 事件中添加了几行代码：

public void contextDestroyed(ServletContextEvent sce) {
...
String delme = sce.getServletContext().getInitParameter("eraseOnExit");
if (delme != null && delme.length() > 0) {
    File del = new File(delme);
    if (del.exists()) {
        System.out.println("Deleting file " + delme);
        del.delete();
    }
}

在 web.xml 中，在开发环境中添加以下内容：

<context-param>
    <description>Workaround for Tomcat starting webapp twice</description>
    <param-name>eraseOnExit</param-name>
    <param-value>/Users/xxx/apache-tomcat-7.0.42/conf/Catalina/localhost/myappname.xml</param-value>
</context-param>

然后下次部署应用程序时，它不会在部署之前再次启动，因此不会启动两次。在部署之前或关闭时删除文件的任何其他想法将不胜感激。

于 2014-01-28T22:37:23.463 回答
4

感谢epoch的回答和 Steven Neiner的回答。

这是我的他们的代码版本。我的不同之处：

  • 将方法标记为synchronized。
    • 理论上不需要，但鉴于我们正在处理奇怪的多次启动问题，安全总比抱歉好。
  • 替换了对第三方实用程序（Spring？）的调用。
  • catalina.base通过在路径中查找某些措辞来检测是否在开发中运行。
  • 删除了static修饰符。使用作为枚举实现的 Singleton。
  • 截至 2016 年 5 月，重写代码以更易于阅读和理解（至少对我而言）。仅进行了简要测试，因此请务必在使用前查看源代码（并且必须完全由您自担风险）。

概念

他们解决此错误的核心是删除以您的 Web 应用程序（您的“servlet 上下文”）名称命名并附加.xml.

例如，如果您的 Web 应用程序名为AcmeApp，请找到并删除名为 的文件AcmeApp.xml。该文件嵌套存储在“Catalina base”文件夹中。

将此删除作为 Web 应用程序运行的最后一步。因此，当 Web 应用程序再次启动时，该文件将不存在，并将重新创建。请记住，这仅在开发模式下。在生产中单独使用 Tomcat 时不会出现该错误。

那么我们如何运行这个变通方法代码作为我们网络应用程序执行的最后一个动作呢？继续阅读。

如何使用

作为Servlet 规范2.3 版和更高版本的标准部分，每个Servlet 容器都有挂钩，可在您的 Web 启动时调用您的代码，并在您的 Web 应用程序关闭时再次调用您的代码。这不是 Tomcat 特定的；Jetty、GlassFish、WildFly/JBoss等等，都包含 Servlet 规范要求的这个特性。

要使用上面显示的代码，请将一个新类添加到您的项目中。将新类命名为“MyServletContextListener.java”。将该类声明为实现ServletContextListener接口。

实现该接口所需的两个方法。当您的 Web 应用程序启动时，您的 Servlet 容器 (Tomcat) 会调用一个方法，保证在第一个用户点击您的应用程序之前运行。当您的 Web 应用程序被 Servlet 容器 (Tomcat) 关闭时，将调用另一种方法。

在contextDestroyed方法中，调用如上所示的方法。像这样：

@Override
public void contextInitialized ( ServletContextEvent sce )
{
    // Web app launching. 
    // This method runs *before* any execution of this web app’s servlets and filters.
    // Do nothing. No code needed here.
}

@Override
public void contextDestroyed ( ServletContextEvent sce )
{
    // Web app shutting down. 
    // This method runs *after* the last execution of this web app’s servlets and filters.
    // Workaround for NetBeans problem with launching Tomcat twice.
    this.workaroundTomcatNetbeansRedeployBug( sce );
}

配置很简单。仅将此类与您的 servlet 类一起包含在WAR 文件/文件夹中。@WebListener注释使Servlet 容器“注意到”这个侦听器类，加载并实例化它，并在适当的时候执行它的每个方法。如果需要，您可以使用替代配置模式而不是注释，但注释是最简单的路线。

这是一个完整的AppListener类作为完整示例。为了更容易阅读和理解，我重新编写了之前发布的此代码版本。

package com.basilbourque;

import java.io.File;
import java.io.FilenameFilter;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

/**
 * Hooks into the web app launching and quitting, as a workaround for Tomcat
 * running from NetBeans causing the web app to rapidly deploy, undeploy and
 * redeploy.
 *
 * © 2016 Basil Bourque. This source code may be used freely, and entirely at
 * your own risk, according to terms of the ISC License at:
 * https://opensource.org/licenses/ISC
 *
 * @author Basil Bourque
 */
@WebListener
public class AppListener implements ServletContextListener {

    @Override
    public void contextInitialized ( final ServletContextEvent servletContextEventArg ) {
        System.out.println ( "Basil launch" );
    }

    @Override
    public void contextDestroyed ( final ServletContextEvent servletContextEventArg ) {
        System.out.println ( "Basil exit" );
        this.workaroundTomcatNetbeansRedeployBug ( servletContextEventArg );
    }

   synchronized private void workaroundTomcatNetbeansRedeployBug ( final ServletContextEvent servletContextEventArg ) {
        // When running Tomcat 8 from NetBeans 8, as we do in development, a bug causes the web app to rapidly deploy, undeploy, and redeploy.
        // This bug causes multiple bad side-effects.
        //
        // Workaround: When running in development mode with NetBeans & Tomcat, delete the XML file with name of web app, found in {catalina-base}/conf/Catalina/localhost/YourWebAppNameHere.xml.
        // Example of file name to delete: If your app is named “AcmeApp”, then in a Vaadin multi-module Maven archetype app, the target file might be named “AcmeApp-ui.xml”.
        // In a simpler project, the target file might be named “AcmeApp.xml”.
        // So we need to determine the name of the web app in a soft-coded fashino.
        // We extract from a context path. For example, '/AcmeApp-ui'. We need to remove that slash (SOLIDUS) at the front.
        // Then we append a “.xml” to create our target file name.
        // We look for that file in the folder nested in the Cataline base folder (see line above for path).
        // If file is found, add it to the list of files to be deleted. That list will have only one element.
        // Lastly, delete the file.
        if ( AppUtility.INSTANCE.isInDevelopmentMode () ) {  // Find a strategy to determine if you are in development mode.
            final String catalinaBase = System.getProperty ( "catalina.base" );// Path to the folder the working folder of this web app.

            final String contextPath = servletContextEventArg.getServletContext ().getContextPath ();
            final String contextName = contextPath.substring ( 1 ); // Strip the SOLIDUS (slash) from first character position. Example: '/AcmeApp-ui' becomes 'AcmeApp-ui'.
            final String fileNameToDelete = contextName + ".xml";

            final File catalinaBaseContext = new File ( catalinaBase , "conf/Catalina/localhost" ); // While in development, running Tomcat from NetBeans, the web app’s name is 'localhost'.
            if ( catalinaBaseContext.exists () && catalinaBaseContext.canRead () ) {  // Confirm that we found the expected configuration folder nested in Catalina’s 'base' folder.
                // Make an array of File objects that match our criterion of having one of our expected file names.
                // Populate this array by defining a filter of filenames via a functional interface, to be applied against each file found in folder.
                final File[] filesToDelete = catalinaBaseContext.listFiles ( new FilenameFilter () {
                    @Override
                    public boolean accept ( File dir , String name ) {
                        boolean accepting = ( name.equals ( fileNameToDelete ) );
                        return accepting;
                    }
                } );

                if ( filesToDelete.length == 0 ) {  // If list of files is empty…
                    // FIXME Handle error. Should always find one file to delete.
                    System.out.println ( "ERROR - Found no file to delete as workaround for NetBeans+Tomcat double-launch bug. Expected file name: " + fileNameToDelete + " | Message # 42ec5857-9c1b-431a-b5c1-2588669a0ee2." );
                    return;
                }

                if ( filesToDelete.length > 1 ) {  // If list of files has more than one file…
                    // FIXME Handle error. Should never find more than one file to delete.
                    System.out.println ( "ERROR - Found more than one file to delete as workaround for NetBeans+Tomcat double-launch bug." + " | Message # 0afbd6ca-3722-4739-81dc-b2916e9dbba4." );
                    return;
                }

                for ( File file : filesToDelete ) {
                    file.delete ();  // Delete first file found in our filtered array.
                    // FIXME You may want to log this deletion.
                    System.out.println ( "TRACE - Deleting file as workaround for NetBeans+Tomcat double-launch bug: " + file + " | Message # 5a78416c-6653-40dc-a98c-6d9b64766d96." );
                    break; // Should be exactly one element in this list. But out of abundant caution, we bail-out of the FOR loop.
                }
            }
        }

    }

}

这是确定是否在开发模式下运行的帮助程序类。阅读评论以进行更多讨论。结果是似乎没有简单干净的方法来检测何时处于开发状态，无法检测何时从 NetBeans 运行 Tomcat 而不是自己运行 Tomcat。我已经问过但没有收到任何更好的解决方案。

警告：您必须更改此isInDevelopmentMode方法以匹配您的特定开发环境。

package com.basilbourque;

import java.util.ArrayList;
import java.util.List;

/**
 * Detects if this web app is running in the Apache Tomcat web container from
 * within NetBeans during development time.
 *
 * © 2016 Basil Bourque. This source code may be used freely, and entirely at
 * your own risk, according to terms of the ISC License at:
 * https://opensource.org/licenses/ISC
 *
 * @author Basil Bourque.
 */
public enum AppUtility {

    INSTANCE;

    transient private Boolean isDevMode;

    synchronized public Boolean isInDevelopmentMode () {

        // There is no simple direct way to detect if running in development.
        // As a workaround, I use some facts specific to my running Tomcat from NetBeans while developing.
        //
        // The “Catalina base” is the folder used by Tomcat’s Catalina module to do the work of your servlets.
        // The names of the folders in the path to that folder can be a clue about running in development.
        //
        // By default, the Catalina base folder is nested within Tomcat’s own folder.
        //
        // If you run NetBeans with a bundled Tomcat installation that path may contain the word “NetBeans”.
        // At least this is the case on Mac OS X where that bundled Tomcat is stored within the NetBeans app (an app is actually a folder in Mac OS X).
        //
        // You mant to create your own folder to hold Tomcat’s “base” folder.
        // I do this on my development machine. I create a folder named something like "apache-tomcat-base-dev" in my home folder.
        // Nested inside that  folder are additional folders for each version of Tomcat I may be using, such as 'base-8.0.33'.
        // Since I do not use such a name on my production environment, I can example the path for that phrasing to indicate development mode.
        //
        if ( null == this.isDevMode ) {  // Lazy-loading.
            // Retrieve the folder path to the current Catalina base folder.
            String catalinaBaseFolderPath = System.getProperty ( "catalina.base" );

            this.isDevMode = Boolean.FALSE;

            // Examine that path for certain wording I expect to occur only in development and never in production.
            List<String> list = new ArrayList<> ();
            list.add ( "Application Support" );// Specific to Mac OS X only.
            list.add ( "NetBeans" );
            list.add ( "apache-tomcat-base-dev" ); // My own name for an external folder to keep Catalina base separate, outside of NetBeans and Tomcat.
            for ( String s : list ) {
                if ( catalinaBaseFolderPath.contains ( s ) ) {
                    this.isDevMode = Boolean.TRUE;
                    break;  // Bail-out of the FOR loop after first hit.
                }
            }
        }

        return this.isDevMode;
    }

}
于 2015-02-06T00:59:35.103 回答
3

首先，感谢史蒂文！这是修复的更便携版本：

/**
 * tomcat workaround bug, in development mode, if tomcat is stopped and application is not un-deployed,
 * the old application will start up again on startup, and then the new code will be deployed, leading
 * to a the app starting two times and introducing subtle bugs, when this app is stopped and in dev mode
 * remove the deployment descriptor from catalina base
 */
private static void preventTomcatNetbeansRedeployBug(final ServletContextEvent sce) {
    final String contextPath = sce.getServletContext().getContextPath();
    final String catalinaBase = System.getProperty("catalina.base");

    if (StringUtil.checkValidity(contextPath, catalinaBase)
            && FrameworkContext.getInstance().isDevEnvironment()) {
        final File catalinaBaseContext = new File(catalinaBase, "conf/Catalina/localhost");
        if (catalinaBaseContext.exists() && catalinaBaseContext.canRead()) {
            final File[] contexts = catalinaBaseContext.listFiles(new FilenameFilter() {
                @Override
                public boolean accept(File dir, String name) {
                    return name.equals(contextPath.substring(1) + ".xml");
                }
            });

            if (contexts != null && contexts.length > 0) {
                LOG.info("Deleting core context[" + contexts[0].getAbsolutePath() + "] since we are in dev");
                contexts[0].delete();
            }
        }
    }
}

PS：用你自己的版本替换未知的引用:)

contextDestroyed从您的实现方法中调用此自定义方法ServletContextListener。

于 2014-02-17T14:17:34.847 回答
2

就我而言，它是（在 NetBeans 中单击“运行”后）：

  • 在 Tomcat 中部署应用程序（不必要）
  • 在 Tomcat 中取消部署应用程序（不必要）
  • 构建应用程序
  • 在 Tomcat 中部署应用程序

我只是通过在运行项目之前清理项目来解决这个问题 - 'clean' -> 'run' :)

于 2019-04-18T07:57:11.137 回答