servlet使用<context-param>元素后createdb显示500,先前createdb使用的是init-param元素

createdb使用init-param能正常访问：
<servlet>
<servlet-name>CreateDBServlet</servlet-name>
<servlet-class>org.sunxin.lesson.jsp.bookstore.CreateDBServlet</servlet-class>
<init-param>
<param-name>driverClass</param-name>
<param-value>com.mysql.jdbc.Driver</param-value>
</init-param>
  <init-param>
<param-name>url</param-name>
<param-value>jdbc:mysql://localhost:3306/mysql</param-value>
</init-param>
  <init-param>
<param-name>password</param-name>
<param-value>12345678</param-value>
</init-param>
  <init-param>
<param-name>user</param-name>
<param-value>root</param-value>
</init-param>
</servlet>

<servlet-mapping>
<servlet-name>CreateDBServlet</servlet-name>
<url-pattern>/createdb</url-pattern>
</servlet-mapping>
******
改用<context-param>元素后出现500错误：

<context-param>
<param-name>driverClass</param-name>
<param-value>com.mysql.jdbc.Driver</param-value>
</context-param>
<context-param>
<param-name>url</param-name>
<param-value>jdbc:mysql://localhost:3306/bookstore</param-value>
</context-param>
<context-param>
<param-name>user</param-name>
<param-value>root</param-value>
</context-param>
<context-param>
<param-name>password</param-name>
<param-value>12345678</param-value>
</context-param>

  <servlet>
<servlet-name>CreateDBServlet</servlet-name>
<servlet-class>org.sunxin.lesson.jsp.bookstore.CreateDBServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>CreateDBServlet</servlet-name>
<url-pattern>/createdb</url-pattern>
</servlet-mapping>
错误：The server encountered an internal error () that prevented it from fulfilling this request.
说是请求太多，但是为什么改用<context-param>后就错了呐？我是用的tomcat6.0.18的exe版本。还有我不能用自带的调用器，自带的Servlet调用器取消注释后，连localhost：8080都打不开了

多贴点错误信息