无法在 persistence.xml 文件中调用 JNDI 资源答案

【问题标题】：Cannot call JNDI resource in persistence.xml file无法在 persistence.xml 文件中调用 JNDI 资源
【发布时间】：2014-04-06 04:48:02
【问题描述】：

虽然看起来很多用户都面临同样的问题，但我必须发布我自己的问题，考虑到目前，已经在场的人没有任何建议对我有用。还是我错过了什么？

这是我的persistence.xml 文件（位于resources/META-INF/ 目录下，在一个maven 项目中）：

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd ">
    <persistence-unit name="brass-unit" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
    <properties>
                <property name="hibernate.connection.datasource" value="java:/comp/env/jdbc/BrassDB"/> 
    </properties>
</persistence-unit>

resources/META-INF下我还有context.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<Context>
    <Resource name="jdbc/BrassDB" auth="Container" type="javax.sql.DataSource" 
              driverClassName="org.postgresql.Driver" 
              url="jdbc:postgresql://localhost:5432/mydb" username="usr" password="pwd" 
              maxActive="20" maxIdle="10" maxWait="-1"/>
</Context>

在web.xml 文件中我有：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>brass_directory_business</display-name>
<welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
</welcome-file-list> 
<resource-ref>
    <description>db connection</description>
    <res-ref-name>jdbc/BrassDB</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
</resource-ref>

关于 web.xml 的注意事项：有时我评论了 resource-ref 标签，但结果相同。

现在，在我的 servlet 中，当我运行它时，一切正常：

InitialContext ctx = null;
try {
    ctx = new InitialContext();
    if (ctx == null) {
        throw new Exception("no context!");
    }
    DataSource ds = (DataSource)ctx.lookup("java:/comp/env/jdbc/BrassDB");
    if (ds == null) {
        throw new Exception("data source not found!");
    }
    Connection conn = ds.getConnection();
    ResultSet rs = conn.createStatement().executeQuery("SELECT * FROM person");
    int n = 0;
    while (rs.next()) {
        n++;
    }
    System.out.println("rs length is: " + n);
} catch (Exception e) {
    e.printStackTrace();
}

但是当我运行这个时：

EntityManagerFactory emf = Persistence.createEntityManagerFactory("brass-unit");
EntityManager em = emf.createEntityManager();       
em.createNamedQuery("Person.findAll", Person.class).getResultList();

我得到了这个例外：

Mar 04, 2014 4:48:56 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [com.banco.Test] in context with path [/brass_directory_business] threw exception
javax.persistence.PersistenceException: Unable to build entity manager factory
    at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:81)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:54)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:55)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
    at com.banco.Test.doPost(Test.java:34)
    at com.banco.Test.doGet(Test.java:27)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:313)
    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:744)
Caused by: org.hibernate.engine.jndi.JndiException: Unable to lookup JNDI name [java:/comp/env/jdbc/BrassDB]
    at org.hibernate.engine.jndi.internal.JndiServiceImpl.locate(JndiServiceImpl.java:117)
    at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.configure(DatasourceConnectionProviderImpl.java:115)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:89)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.buildJdbcConnectionAccess(JdbcServicesImpl.java:260)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:94)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:89)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
    at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:850)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:843)
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.withTccl(ClassLoaderServiceImpl.java:399)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:842)
    at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:73)
    ... 26 more
Caused by: javax.naming.NameNotFoundException: Name [java:/comp/env/jdbc/BrassDB] is not bound in this Context. Unable to find [java:].
    at org.apache.naming.NamingContext.lookup(NamingContext.java:819)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:153)
    at javax.naming.InitialContext.lookup(InitialContext.java:415)
    at org.hibernate.engine.jndi.internal.JndiServiceImpl.locate(JndiServiceImpl.java:114)
    ... 42 more

我的pom.xml 看起来像：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    //......
    <dependencies>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.1.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>4.3.1.Final</version>
        </dependency>
        //...
    </dependencies>
    <build>
        <plugins>
            <plugin>
        //...
            </plugin>
        </plugins>
    </build>
</project>

我正在使用 tomcat 7.0.52 作为服务器。有人对如何解决我的问题有任何建议吗？

【问题讨论】：

标签： java postgresql tomcat7 datasource persistence.xml

【解决方案1】：

对我来说，这个问题似乎是一个 Hibernate 问题。我刚把hibernate版本改成4.2.7，效果很好。

【讨论】：

【解决方案2】：

我有另一个想法：

1.添加<exclude-unlisted-classes>false</exclude-unlisted-classes>到你的persistence.xml，<persistence-unit>elemet

2.将以下内容添加到您的 persistence.xml，<persistence-unit>/<properties> 元素：

<property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:mem:standalone"/>
<property name="javax.persistence.jdbc.user" value="sa"/>
<property name="javax.persistence.jdbc.password" value=""/>

此外，请尝试从 pom.xml 中删除 hibernate-core 依赖项。

现在您应该可以使用实体管理器了。如果您需要 JDBC 连接，只需从 EntityManager 实例中获取它（而不是使用 JNDI 获取它的方式）。

【讨论】：

我希望将其指定为DataSource，而不是JDBC 连接。无论如何，如您所见，这是我使用的版本中的 Hibernate 问题。