Tomcat 7 LinkageError：加载程序约束违规

Question

INFO: Deploying web application archive test-1.0-SNAPSHOT.war
20-Sep-2011 12:08:42 org.apache.catalina.loader.WebappClassLoader validateJarFile
INFO: validateJarFile(C:\software\apache-tomcat-7.0.21\webapps\test-1.0-SNAPSHOT\WEB-INF\lib\servlet-api-2.5.jar) - jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
20-Sep-2011 12:08:42 com.sun.faces.config.ConfigureListener contextInitialized
INFO: Initializing Mojarra 2.1.0 (SNAPSHOT 20100817) for context '/test-1.0-SNAPSHOT'
20-Sep-2011 12:08:42 com.sun.faces.spi.InjectionProviderFactory createInstance
INFO: JSF1048: PostConstruct/PreDestroy annotations present.  ManagedBeans methods marked with these annotations will have said annotations processed.
20-Sep-2011 12:08:43 com.sun.faces.config.ConfigureListener contextInitialized
SEVERE: Critical error during deployment: 
java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.registerELResolverAndListenerWithJsp(ConfigureListener.java:684)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:240)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4723)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5226)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5221)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
20-Sep-2011 12:08:43 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class com.sun.faces.config.ConfigureListener
java.lang.RuntimeException: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:290)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4723)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5226)
    at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5221)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/catalina/loader/WebappClassLoader) of the current class, com/sun/faces/config/ConfigureListener, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
    at com.sun.faces.config.ConfigureListener.registerELResolverAndListenerWithJsp(ConfigureListener.java:684)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:240)
    ... 8 more
20-Sep-2011 12:08:43 org.apache.catalina.core.StandardContext startInternal
SEVERE: Error listenerStart
20-Sep-2011 12:08:43 org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [/test-1.0-SNAPSHOT] startup failed due to previous errors

我正在尝试运行 mkyong hello world JSF2 示例http://www.mkyong.com/jsf2/jsf-2-0-hello-world-example/

POM.xml 是

<dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-api</artifactId>
        <version>2.1.0-b03</version>
    </dependency>
    <dependency>
        <groupId>com.sun.faces</groupId>
        <artifactId>jsf-impl</artifactId>
        <version>2.1.0-b03</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.1</version>
    </dependency>

    <dependency>
        <groupId>com.sun.el</groupId>
        <artifactId>el-ri</artifactId>
        <version>1.0</version>
        <scope>provided</scope>
    </dependency>

这个线程loader constraint violation 描述了tomcat 6 中的相同问题，但它无助于解决我的问题。

Answer 1

我不使用 Maven，但鉴于 Pascal Thivent 在您的链接问题中的回答，您似乎需要将 Maven 依赖项标记为 provided，只要目标运行时已经附带了它。

Tomcat 作为一个简单的 servlet 容器，随 JSP、Servlet 和 EL 开箱即用（只有 JSF 和 JSTL 没有）。您收到的异常消息表明类路径中的 JSP API 重复。我建议您也将pom.xml 中的JSP 和Servlet 条目设置为provided。

此外，在您解决了问题Mojarra 2.1.0 does not work in Tomcat 中所述的问题后，您将遇到第二个主要问题。升级到 Mojarra 2.1.1 或更新版本（目前为 2.1.3）。另请参阅Mojarra download page for pom sn-ps。

Answer 2

注释掉

<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.1</version>
</dependency> 

为我做了诀窍。似乎因为已经提供了jsp，所以添加依赖项是不必要的并产生错误

Answer 3

此答案是对 BalusC 答案的补充。希望这会有所帮助。

使用 Tomcat 7 作为容器。您必须考虑默认的Shared Library Files。

对我来说，目录$TOMCATHOME/lib中有这样的文件：

1. annotations-api.jar
2. catalina-ant.jar
3. catalina-ha.jar
4. ...
5. jsp-api.jar
6. servlet-api.jar
7. ...

这就是为什么您必须将 servlet-api、jsp-api 和 el-ri 标记为 provided，甚至排除 JAR。

Answer 4

尝试把你的jar文件放到你的项目BuildPath->Configure BuildPath->Libraries->Add External Jar..