我正在使用 Eclipse 用 Java 编写一个 Web 应用程序，使用 Struts2 框架连接到与 MySQL 数据库通信的 Tomcat 7 服务器。我的程序正在运行，但我的代码中硬编码了连接的值。我想使用 context.xml 或我创建的一个进行连接，这样它就可以移植，并且不需要登录页面进行连接。我没有完全遵循上下文配置。我创建了一个名为 OS1.xml 的上下文 xml 文件，并将其放在 C:\Users\Rich\Tomcat\conf\Catalina\localhost 中。该应用程序从 webapps 目录 C:\Users\Rich\Tomcat\webapps 启动，其中包含 OS1.war 文件。
有人可以帮助我了解如何在 Tomcat 中使用我的上下文文件并从我的程序中调用它吗？
这是我的 ConnectionModel 类中应该调用的部分。
public class ConnectionModel {
public ArrayList<Table> Systems() throws SQLException {
Connection con = null;
ResultSet rs = null;
try {
InitialContext ctx = new InitialContext();
DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/os");
con = ds.getConnection();
这是我的 web.xml 文件
<display-name>OS1</display-name>
<welcome-file-list>
<welcome-file>enter.jsp</welcome-file>
</welcome-file-list>
<filter>
<filter-name>struts2</filter-name>
<filter-class>
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<resource-ref>
<description>MySQL Datasource </description>
<res-ref-name>jdbc/os</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
这是我的上下文 xml 文件，名为 OS1.xml，位于
C:\Users\Rich\Tomcat\conf\Catalina\localhost
<Context docBase="C:/Users/Rich/Tomcat/webapps/OS1.war" path="/OS1" reloadable="true">
<Resource>
name="jdbc/os"
auth="Container"
type="javax.sql.DataSource"
maxActive="100"
maxIdle="30"
maxWait="10000"
username="someone"
password="password"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/os"
</Resource>
</Context>
我收到以下错误。
WARNING: A docBase C:\Users\Rich\Tomcat\webapps\OS1.war inside the host appBase has
been specified, and will be ignored
Jun 05, 2013 12:43:54 PM org.apache.catalina.deploy.NamingResources initInternal
WARNING: Failed to create MBean for naming resource [null]
java.lang.NullPointerException
at javax.management.ObjectName.quote(ObjectName.java:1833)
at org.apache.catalina.mbeans.MBeanUtils.createObjectName(MBeanUtils.java:569)
at org.apache.catalina.mbeans.MBeanUtils.createMBean(MBeanUtils.java:183)
at
org.apache.catalina.deploy.NamingResources.initInternal(NamingResources.java:934)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:102)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:139)
at
org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5163)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:633)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:657)
at
org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1636)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
Jun 05, 2013 12:43:54 PM org.apache.catalina.core.ContainerBase addChildInternal
SEVERE: ContainerBase.addChild: start:
org.apache.catalina.LifecycleException: Failed to start component
[StandardEngine[Catalina].StandardHost
[localhost].StandardContext[/OS1]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:633)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:657)
at
org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1636)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.NullPointerException
at java.util.StringTokenizer.<init>(StringTokenizer.java:199)
at java.util.StringTokenizer.<init>(StringTokenizer.java:221)
at
org.apache.catalina.core.NamingContextListener.createSubcontexts(NamingContextListener.
java:1272)
at
org.apache.catalina.core.NamingContextListener.addResource(NamingContextListener.
java:1083)
at
org.apache.catalina.core.NamingContextListener.createNamingContext(
NamingContextListener.java:672)
at org.apache.catalina.core.NamingContextListener.lifecycleEvent(
NamingContextListener.java:271)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(
LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.StandardContext.startInternal(
StandardContext.java:5269)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 11 more
Jun 05, 2013 12:43:54 PM org.apache.catalina.startup.HostConfig deployDescriptor
SEVERE: Error deploying configuration descriptor
C:\Users\Rich\Tomcat\conf\Catalina\localhost\OS1.xml
java.lang.IllegalStateException: ContainerBase.addChild: start:
org.apache.catalina.LifecycleException: Failed to
start component
[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/OS1]]
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:904)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:633)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:657)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(
HostConfig.java:1636)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
然后我收到此错误，我认为是因为我的上下文文件未正确使用:
无法为连接 URL“null”创建类“”的 JDBC 驱动程序
感谢任何帮助!
提前致谢， 丰富
最佳答案
您的上下文 xml 文件应如下所示:
<Context docBase="C:/Users/Rich/Tomcat/webapps/OS1.war" path="/OS1" reloadable="true">
<Resource
name="jdbc/os"
auth="Container"
type="javax.sql.DataSource"
maxActive="100"
maxIdle="30"
maxWait="10000"
username="someone"
password="password"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/os"
/>
使用资源节点的参数而不是资源正文文本。我在没有参数的资源中遇到了类似的错误
java.lang.NullPointerException
at javax.management.ObjectName.quote(ObjectName.java:1833)
看起来 Catalina 没有强制字段验证。
关于java - 有人可以帮助我了解如何在 Tomcat 中使用我的上下文文件并从我的程序中调用它吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16949285/