maven库引入jfreechart，不要被迷惑，jfreechart有两套jar，其中一个是osgi的jar

下面把我的maven配置pom.xml的代码粘出来就明白了

<dependency>
             <groupId>org.jfree.chart</groupId>
             <artifactId>com.springsource.org.jfree.chart</artifactId>
             <version>1.0.9</version>
         </dependency>
         <dependency>
             <groupId>org.jfree</groupId>
             <artifactId>com.springsource.org.jfree</artifactId>
             <version>1.0.12</version>
         </dependency>
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>com.springsource.javax.servlet</artifactId>
             <version>2.4.0</version>
             <scope>provided</scope>
         </dependency>

引用这三个就好。可以放心引用了