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我試圖連接到會話bean。我嘗試了許多與Google發現的不同方式，但我總是得到相同的錯誤，因爲我的JNDI查找始終返回NULL。訪問遠程/本地會話Bean
這裏的錯誤：
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)
所以，我可能錯過了一些配置，但我對這個東西的新手。一點幫助？
這裏是我的實體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
}
我的會話Bean：
我的遠程接口：
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);
}
我的本地接口：
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);
}
在web.xml參考：
<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的客戶端代碼：
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);
我使用的MyEclipse開發和Tomcat服務器