java.lang.ClassCastException：无法将spark.servlet.SparkFilter强制转换为javax.servlet.Filter

Question

我正在尝试通过Tomcat运行Java Spark Webservice>我正在使用Maven。 Maven应用程序可以编译，但是当我执行mvn tomcat:run ，我得到以下信息：

[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building art2 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] >>> tomcat-maven-plugin:1.1:run (default-cli) @ art2 >>>
[INFO] 
[INFO] --- maven-resources-plugin:2.3:resources (default-resources) @ art2 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/pierceg/SR_Repos/ART2/art2_java/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.2:compile (default-compile) @ art2 ---
[INFO] No sources to compile
[INFO] 
[INFO] <<< tomcat-maven-plugin:1.1:run (default-cli) @ art2 <<<
[INFO] 
[INFO] --- tomcat-maven-plugin:1.1:run (default-cli) @ art2 ---
[INFO] Running war on http://localhost:8080/art2
[INFO] Using existing Tomcat server configuration at /home/pierceg/SR_Repos/ART2/art2_java/target/tomcat
Aug 05, 2015 2:26:14 PM org.apache.catalina.startup.Embedded start
INFO: Starting tomcat server
Aug 05, 2015 2:26:14 PM org.apache.catalina.core.StandardEngine start
INFO: Starting Servlet Engine: Apache Tomcat/6.0.29
Aug 05, 2015 2:26:14 PM org.apache.catalina.core.StandardContext filterStart
SEVERE: Exception starting filter SparkFilter
java.lang.ClassCastException: spark.servlet.SparkFilter cannot be cast to javax.servlet.Filter
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
    at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4001)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4651)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)
    at org.apache.catalina.startup.Embedded.start(Embedded.java:825)
    at org.codehaus.mojo.tomcat.AbstractRunMojo.startContainer(AbstractRunMojo.java:558)
    at org.codehaus.mojo.tomcat.AbstractRunMojo.execute(AbstractRunMojo.java:255)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    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:497)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)

Aug 05, 2015 2:26:14 PM org.apache.catalina.core.StandardContext start
SEVERE: Error filterStart
Aug 05, 2015 2:26:14 PM org.apache.catalina.core.StandardContext start
SEVERE: Context [/art2] startup failed due to previous errors

我的web.xml看起来像：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <display-name>ART2</display-name>
    <filter>
        <filter-name>SparkFilter</filter-name>
        <filter-class>spark.servlet.SparkFilter</filter-class>
        <init-param>
            <param-name>applicationClass</param-name>
            <param-value>com.simplerelevance.Main</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>SparkFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

我在这里查看了问题，但WEB-INF文件夹中没有lib文件夹。 此错误消息是什么意思？ 我是Tomcat和Spark的新手，但是我读到的内容告诉我我正在尝试使用多个servlet.Filter类，但是我不知道在哪里做

Answer 1

当您在pom.xml中包含对spark-core的依赖时，需要排除码头：

<dependencies>
    <dependency>
        <groupId>com.sparkjava</groupId>
        <artifactId>spark-core</artifactId>
        <version>2.1</version>
        <exclusions>
            <exclusion>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-server</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-webapp</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

Answer 2

我遇到了类似的问题，并通过从pom.xml文件中的spark-core依赖项中排除Javax Servlet来解决了该问题，如下所示：

<dependency>
    <groupId>com.sparkjava</groupId>
    <artifactId>spark-core</artifactId>
    <version>2.5.5</version>
    <exclusions>
        <exclusion>
            <artifactId>javax.servlet-api</artifactId>
            <groupId>javax.servlet</groupId>
        </exclusion>
    </exclusions>
</dependency>