概念

Question

我正在使用NetBeans，Tomcat似乎在.war应用程序中部署两次，这是网络应用的双重启动。

我已经尝试过Tomcat 6和7以及相同的结果。

我有一个Spring MVC，Hibernate和Thymeleaf应用程序。 META-INF下的Context.xml具有以下内容：

<?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]

它成功启动。

我不明白为什么Tomcat会两次部署应用程序。第一次在新的tomcat实例上部署应用程序时不会发生这种情况，因为website.xml文件尚未位于tomcats / conf / catalina / localhost文件夹中。但是当我再次停止并从netbeans运行tomcat时，website.xml文件仍然在/ conf / catalina / localhost文件夹中，但在第二次部署即将发生之前就被删除并重新部署。

我已经尝试将Tomcat的server.xml文件中的autoDeploy设置为false，但它没有帮助。

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

每次tomcat停止时，可能是Tomcat应该删除/ 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"
/>

Answer 1

我发现删除文件conf / localhost / myappname.xml会阻止应用初始化两次。基本上Tomcat正在重新启动，并重新启动旧版本的应用程序。然后当Netbeans部署它时它再次启动。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，它将不会在部署之前再次启动，因此不会启动两次。在部署或关闭之前删除文件的任何其他想法都将不胜感激。

Answer 2

感谢the answer by epoch和answer by Steven Neiner。

这是我的代码版本。我的不同之处：

标记方法为synchronized。
- 理论上不需要，但鉴于我们在处理奇怪的多重启动问题，最好是安全而不是抱歉。
取代了对第三方实用程序的调用（Spring？）。
通过查找catalina.base路径中的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2016-05，重写代码更容易阅读和理解（至少对我来说）。仅进行了简单测试，因此请务必在使用前查看源代码（必须完全使用，风险自负）。

概念

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

例如，如果您的网络应用程序名为AcmeApp，请找到并删除名为AcmeApp.xml的文件。该文件存储在“Catalina base”文件夹中。

将此删除作为网络应用运行的最后一步。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，这只是在开发模式下。在生产中单独使用Tomcat时不会发生错误。

那么我们如何运行此变通方法代码作为我们的Web应用程序执行的最后一个步骤？请继续阅读。

如何使用

作为Servlet spec版本2.3及更高版本的标准版本，每个Servlet container都可以在您的网络启动时调用您的代码，并在您的网络应用程序关闭时再次调用。这不是Tomcat特有的; Jetty，GlassFish，WildFly/JBoss等等，都包含Servlet规范要求的此功能。

要使用上面显示的代码，请在项目中添加一个新类。将新类命名为＆＃34; MyServletContextListener.java＆＃34;。将该类声明为实现ServletContextListener接口。

实现此接口所需的两种方法。当您的Web应用程序启动时，您的Servlet容器（Tomcat）会调用一种方法，保证在第一个用户访问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，将调用另一个方法。

在contextDestroyed方法中，调用上面显示的方法。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类一起包括WAR file/folder。 @WebListener注释使Servlet容器“注意”此侦听器类，加载并实例化它，并在适当时执行其每个方法。如果需要，您可以使用备用配置模式而不是注释，但注释是最简单的路径。

这是一个完整的 AppListener 类作为完整示例。我已经重新编写了此代码的先前发布版本，以便于阅读和理解。

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.
                }
            }
        }

    }

}

这是帮助类确定是否在开发模式下运行。阅读评论以获得更多讨论。结果是在开发时似乎没有简单的干净方法来检测，无法检测何时从NetBeans运行Tomcat而不是自己运行Tomcat。 I have asked但尚未收到任何更好的解决方案。

CAVEAT：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;
    }

}

Answer 3

首先，谢谢史蒂文！这是一个更便携的修复版本：

/**
 * 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：用你自己的版本代替未知的引用：）

使用contextDestroyed实施的ServletContextListener方法调用此自定义方法。

Answer 4

就我而言，是这样（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
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该问题-'clean'->'run'：）

Tomcat在netbeans中部署相同的应用程序两次

4 个答案:

概念

如何使用