如何使用 Eclipse 和 Tomcat 为没有 web.xml 的动态 Web 项目创建 JNDI

Question

我想知道如何使用 Eclipse Kepler 和 Tomcat 7 为 MySQL 数据库创建 JNDI 条目（是否有 Eclipse 插件？）。

当我使用 Eclipse 创建动态 Web 项目时，我没有检查“生成 web.xml 部署描述符”，所以我的项目中没有 web.xml 文件。

Answer 1

JDNI 资源定义在 context.xml¹ 的 Tomcat 的 <Context> 元素中声明，而不是在新应用程序的 web.xml 中声明。所以不管是不是生成的，其实都无所谓。

<Context>
<Resource name="jdbc/YourDB" auth="Container" 
          type="javax.sql.DataSource" 
          username="username" password="password"
          driverClassName="com.mysql.jdbc.Driver"
          url="jdbc:mysql://dbserver:dbport/actualDbname"/>
</Context>

如果您的应用程序中有 web.xml，则需要这样的条目来引用上述数据源：

<resource-ref>
  <res-ref-name>jdbc/YourDB</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
</resource-ref>

由于您选择不使用 web.xml，因此您可以使用注释：

@Resource(lookup = "java:comp/env/jdbc/YourDB")
private DataSource dataSource;

---

^{1 Context的定义有多种方式，参考Tomcat在Defining a Context上的定义。}

Answer 2

当我发布问题时，我忘了说我正在使用 Hibernate 并包含文件。

hibernate.cfg.xml 是：

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE 
hibernate-configuration 
PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.datasource">java:comp/env/jdbc/ExemplosWeb</property>

    <property name="hibernate.connection.username">TheUsername</property>
    <property name="hibernate.connection.password">ThePassword</property>

    <property name="hibernate.connection.pool_size">10</property>
    <property name="show_sql">true</property>
    <property name="format_sql">true</property>
    <property name="hibernate.use_sql_comments">true</property>
    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.hbm2ddl.auto">create-drop</property>
    <property name="current_session_context_class">thread</property>
    <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

    <!-- One to One Unidirecional -->
    <mapping class="relacionamentoHibernate.bean.PaiOneToOneUnidirecional"/>
    <mapping class="relacionamentoHibernate.bean.FilhoOneToOneUnidirecional"/>
</session-factory>

有一个 Hibernate util 类：

package hibernateUtil;

import javax.annotation.Resource;
import org.hibernate.*;
import org.hibernate.cfg.*;

@Resource(lookup="java:comp/env/jdbc/exemplosweb")
@SuppressWarnings("deprecation")
public class HibernateUtil 
{
    private static final SessionFactory sessionFactory;
    static 
    {
        try 
        {
            // Create the SessionFactory from hibernate.cfg.xml
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } 
        catch (HibernateException e) 
        {
            // Make sure you log the exception, as it might be swallowed
            e.printStackTrace();
            throw new ExceptionInInitializerError(e);
        }
        catch (NoClassDefFoundError e) 
        {
            e.printStackTrace();
            throw new NoClassDefFoundError("static HibernateUtil");
        }
    }

    public static SessionFactory getSessionFactory() 
    {
        return sessionFactory;
    }
}

我得到了这个例外：

Fev 26, 2014 7:02:46 PM org.hibernate.annotations.common.Version <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {4.0.1.Final}
Fev 26, 2014 7:02:46 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {4.1.4.Final}
Fev 26, 2014 7:02:46 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
Fev 26, 2014 7:02:46 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
Fev 26, 2014 7:02:46 PM org.hibernate.cfg.Configuration configure
INFO: HHH000043: Configuring from resource: /hibernate.cfg.xml
Fev 26, 2014 7:02:46 PM org.hibernate.cfg.Configuration getConfigurationInputStream
INFO: HHH000040: Configuration resource: /hibernate.cfg.xml
Fev 26, 2014 7:02:46 PM org.hibernate.internal.util.xml.DTDEntityResolver resolveEntity
WARN: HHH000223: Recognized obsolete hibernate namespace      http://hibernate.sourceforge.net/. Use namespace http://www.hibernate.org/dtd/ instead.  Refer to Hibernate 3.6 Migration Guide!
Fev 26, 2014 7:02:46 PM org.hibernate.cfg.Configuration doConfigure
INFO: HHH000041: Configured SessionFactory: null
org.hibernate.service.jndi.JndiException: Unable to lookup JNDI name [java:comp/env/jdbc/ExemplosWeb]
    at org.hibernate.service.jndi.internal.JndiServiceImpl.locate(JndiServiceImpl.java:68)
    at org.hibernate.service.jdbc.connections.internal.DatasourceConnectionProviderImpl.configure(DatasourceConnectionProviderImpl.java:116)
    at org.hibernate.service.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:75)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:159)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:131)