求指点这个问题怎么解决

[ERROR]-[Thread: http-bio-8888-exec-10]-[com.jfinal.core.ActionHandler.handle()]: com.ye.WeixinApiController.createMenu() : /api/createMenu

java.lang.RuntimeException: java.lang.NoClassDefFoundError: com/alibaba/fastjson/serializer/ObjectSerializer

<dependency>

<groupId>com.jfinal</groupId>

<artifactId>jfinal</artifactId>

<version>4.1</version>

</dependency>

<dependency>

<groupId>com.jfinal</groupId>

<artifactId>jfinal-weixin</artifactId>

<version>2.3</version>

</dependency>

<dependency>

<groupId>log4j</groupId>

<artifactId>log4j</artifactId>

<version>1.2.16</version>

</dependency>    

</dependencies>

<build>

<finalName>zf</finalName>

<plugins>

<plugin>

<artifactId>maven-compiler-plugin</artifactId>

<version>3.1</version>

<configuration>

<source>1.8</source>

<target>1.8</target>

</configuration>

</plugin>

<plugin>

<groupId>org.apache.tomcat.maven</groupId>

<artifactId>tomcat7-maven-plugin</artifactId>

<version>2.2</version>

<configuration>

<path>/zf</path>

<port>8888</port>

<uriEncoding>UTF-8</uriEncoding>

<url>http://localhost:8888/manager/html</url>

<server>tomcat7</server>

</configuration>

</plugin>

</plugins>