在maven项目中使用apache cxf中遇到异常 java.lang.ClassCastException: org.springframework.web.filter.CharacterEncodingFilter cannot be cast to javax.servlet.Filter

使用maven虽然很方便,写一个dependency的标签就可以直接从仓库下载对应的jar包,还能处理该jar包的继承依赖关系.但是同时需要你对jar包更加了解,如果依赖关系很复杂,那么很可能会产生jar包冲突,从而使项目报一些莫名其妙的异常.

在用apache cxf的过程中就出现了这样的问题.

1,在项目的pom.xml中加入apache cxf的依赖配置:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.yueguang.maven</groupId>
    <artifactId>springApacheCXF</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>springApacheCXF Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${springVersion}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${springVersion}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${springVersion}</version>
        </dependency>
        <dependency>
 <groupId>org.apache.cxf</groupId>
            <artifactId>apache-cxf</artifactId>
            <version>3.0.2</version>
            <!-- type默认为jar文件,当值为pom的时候代表引入的是一个项目.相当于多个jar文件 -->
            <type>pom</type>
        </dependency>
    </dependencies>
    <build>
        <finalName>springApacheCXF</finalName>
    </build>
    <properties>
        <springVersion>3.2.5.RELEASE</springVersion>
    </properties>
</project>

2,项目报了如下异常:

严重: Exception starting filter encodingFilter
java.lang.ClassCastException: org.springframework.web.filter.CharacterEncodingFilter 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:132)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
    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:116)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:347)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:154)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:582)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:214)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:158)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    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)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:46)
2015-3-6 10:14:39 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2015-3-6 10:14:39 org.apache.catalina.core.StandardContext start
严重: Context [/springApacheCXF] startup failed due to previous errors

搜索查找后发现,其实这个异常是因为

tomcat 启动后先将tomcat/lib目录下的jar包全部读入内存，如果webapps目录里的应用程序中WEB-INF/lib目录下有相同的包，将无法加载，不同版本的包之间也会造成类似问题.

那么具体是哪个jar包呢?是:geronimo-servlet_3.0_spec-1.0.jar 就是在pom中引入的cxf项目中的一个jar包.

刚开始想着可以直接把该jar包从builpath中删除,发现删除不掉.(因为属于cxf项目的一部分?),然后想到maven中可以用exclusion标签排除依赖.于是最终的解决方案如下:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.yueguang.maven</groupId>
    <artifactId>springApacheCXF</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>springApacheCXF Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${springVersion}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${springVersion}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${springVersion}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.cxf</groupId>
            <artifactId>apache-cxf</artifactId>
            <version>3.0.2</version>
            <!-- type默认为jar文件,当值为pom的时候代表引入的是一个项目.相当于多个jar文件,必须填写 -->
            <!-- 多个jar包中和容器的jar包有冲突怎么办? -->
            <type>pom</type>
            <exclusions>
                <exclusion>
                    <groupId>org.apache.geronimo.specs</groupId>
                    <artifactId>geronimo-servlet_3.0_spec</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>
    <build>
        <finalName>springApacheCXF</finalName>
    </build>
    <properties>
        <springVersion>3.2.5.RELEASE</springVersion>
    </properties>
</project>

记录下来,以免再犯..