Tomcat jdbc连接“；nullpointerexception“；为了王国

我试图在servlet中使用realm来实现安全性

这是WEB-IF/WEB.xml的领域部分

<security-constraint>
    <web-resource-collection>
        <web-resource-name>X</web-resource-name>
        <url-pattern>/karbar/*</url-pattern>
    </web-resource-collection>
    <auth-constraint>
        <role-name>karbar</role-name>
    </auth-constraint>
</security-constraint>

<security-constraint>
    <web-resource-collection>
        <web-resource-name>Y</web-resource-name>
        <url-pattern>/modir/*</url-pattern>
    </web-resource-collection>
    <auth-constraint>
        <role-name>modir</role-name>
    </auth-constraint>
</security-constraint>
<security-role>
    <role-name>modir</role-name>
</security-role>
<security-role>
    <role-name>karbar</role-name>
</security-role>

---

对不起，伙计们。我认为这是Intellij12.0或tomcat中的一个bug或其他东西！ 为了检查jdbc驱动程序，我运行了另一个项目，我知道它应该运行良好。它做到了，然后我回到上面的项目，它也工作得很好

我不知道发生了什么事。为什么会有问题，为什么会突然消失

<Realm
            className="org.apache.catalina.realm.JDBCRealm"
            driverName="oracle.jdbc.driver.OracleDriver"
            conncetionURL="jdbc:oracle:thin:@localhost:1521:orcl"
                connectionName="kian"
                connectionPassword="myjava123"
                userTable="users"
                userNameCol="name"
                userCredCol="password"
                userRoleTable="roles"
                roleNameCol="user_role"
   />

INFO: Starting Servlet Engine: Apache Tomcat/7.0.19
java.lang.NullPointerException
   at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:358)
at org.apache.catalina.realm.JDBCRealm.open(JDBCRealm.java:711)
at org.apache.catalina.realm.JDBCRealm.startInternal(JDBCRealm.java:782)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1026)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.startup.Catalina.start(Catalina.java:621)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:450)
Disconnected from server