配置c3p0连接池报错 No set method found for property怎么回事啊？

在项目的META-INF下新建context.xml：<Context>
<Resource
    description="DB Connection" 
name="jdbc/mysqlds"
auth="Container"
type="com.mchange.v2.c3p0.ComboPooledDataSource"
factory="org.apache.naming.factory.BeanFactory"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://127.0.0.1:3306/hibernate"
user="root"
password="123"
maxPoolSize="20" 
      minPoolSize="3" 
nitialPoolSize="10"
/>
</Context>
servlet中测试的部分代码：
Context context = new InitialContext();
DataSource dataSource = (DataSource)context.lookup("java:/comp/env/jdbc/mysqlds");
conn = dataSource.getConnection();错误消息：javax.naming.NamingException: No set method found for property: nitialPoolSize
at org.apache.naming.factory.BeanFactory.getObjectInstance(BeanFactory.java:215)
at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:140)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.apache.naming.NamingContext.lookup(NamingContext.java:793)
at org.apache.naming.NamingContext.lookup(NamingContext.java:140)
at org.apache.naming.NamingContext.lookup(NamingContext.java:781)
at org.apache.naming.NamingContext.lookup(NamingContext.java:140)
at org.apache.naming.NamingContext.lookup(NamingContext.java:781)
at org.apache.naming.NamingContext.lookup(NamingContext.java:140)
at org.apache.naming.NamingContext.lookup(NamingContext.java:781)
at org.apache.naming.NamingContext.lookup(NamingContext.java:153)
at org.apache.naming.SelectorContext.lookup(SelectorContext.java:137)
at javax.naming.InitialContext.lookup(InitialContext.java:392)
at com.wjf.CSPO.doGet(CSPO.java:28)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445)
at java.lang.Thread.run(Thread.java:619)我只在tomcat的lib下放了一个c3p0的jar包，对配置不太了解，
请问factory="org.apache.naming.factory.BeanFactory"这句什么意思？是不是没有引入相关的包？还是其他问题？