如何解决访问远程/本地会话Bean
| 我正在尝试连接到会话bean。我尝试了很多与Google一起找到的方法,但是由于我的JNDI查找总是返回NULL,所以总是会遇到相同的错误。 这是错误:java.lang.NullPointerException
at org.apache.jsp.index_jsp._jspService(index_jsp.java:85)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:317)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:204)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:311)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
因此,我可能缺少一些配置,但是我是新手。一点帮助?
这是我的实体Bean:
package beans;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.*;
import org.hibernate.annotations.GenericGenerator;
@Entity
public class Album {
@Id
@Column(name=\"idalbum\")
@GeneratedValue(generator=\"album_idalbum_seq\")
@GenericGenerator(name=\"album_idalbum_seq\",strategy = \"increment\")
private int id;
@Column(name=\"nomealbum\")
private String nome;
@ManyToMany
@JoinTable(name = \"albumfaixas\",joinColumns = {
@JoinColumn(name = \"idalbum\")
},inverseJoinColumns = {
@JoinColumn(name=\"idfaixas\")
}
)
private Set<Faixas> faixas = new HashSet<Faixas>();
public Album() {}
//gets and sets
}
我的会话Bean:
package DAO;
import org.hibernate.*;
import sFactory.*;
import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import beans.*;
@Stateless
public class AlbumDAO implements AlbumRemote {
@PersistenceContext
private EntityManager entityManager;
public List<Album> listaAlbuns() { ... code ... }
public void createAlbum(Album f) { ... code ... }
public void updateAlbum(Album f) { ... code ... }
public void deleteAlbum(Album f) { ... code ... }
}
我的远程接口:
package DAO;
import javax.ejb.Remote;
import java.util.List;
import beans.Album;
@Remote
public interface AlbumRemote {
public List<Album> listaAlbuns();
public void createAlbum(Album f);
public void updateAlbum(Album f);
public void deleteAlbum(Album f);
}
我的本地界面:
package DAO;
import javax.ejb.Local;
import java.util.List;
import beans.Album;
@Local
public interface AlbumLocal {
public List<Album> listaAlbuns();
public void createAlbum(Album f);
public void updateAlbum(Album f);
public void deleteAlbum(Album f);
}
web.xml中的参考:
<ejb-ref>
<ejb-ref-name>ejb/AlbumRemote</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<home>DAO.AlbumLocal</home>
<remote>DAO.AlbumRemote</remote>
</ejb-ref>
我的JSP客户端代码:
Context initCtx = new InitialContext();
Context ctx = (Context) initCtx.lookup(\"java:comp/env\");
Object x = ctx.lookup(\"ejb/AlbumRemote\");
AlbumRemote fr = (AlbumRemote)PortableRemoteObject.narrow(x,AlbumRemote.class);
fr.createAlbum(fx1);
我正在使用myeclipse进行开发,并使用Tomcat作为服务器
解决方法
您真的很亲密。放入openejb.war文件,此代码应该起作用。
Tomcat本身并不支持EJB,但是可以通过OpenEJB轻松实现。实际上,我们现在将此组合称为Apache TomEE,并且正在Java EE 6 Web Profile对其进行认证的过程中。因此它将在Glassfish,JBoss,Geronimo等行列中。
如果您还没有一个文件,请确保您的应用程序中有一个定义持久性单元的“ 7”文件。
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