如何设置本地EJB bean的JNDI属性

Question

我正在尝试使用Maven、JPA和EJB学习一些Java EE。我现在尝试通过使用InitialContext来进行基本的EJB查找，只是为了稍微熟悉一下EJB之类的东西。我对这一点非常陌生，甚至不能做网上的教程，因为注释对我来说很有意义。我现在已经花了大约4个小时阅读EJB、JNDI和InitialContext，但注意到我读到的内容告诉了我需要知道的内容。

我正在尝试查找一个本地ejb，该ejb从JPA实体执行基本的读取操作。我尝试过"java:comp/env/beanName"JNDI名称，但它仍然不起作用。我尝试了在这篇文章中找到的解决方案，但它也不起作用。这就是我所做的。

我有一个简单的ejb接口

package ejb;
import javax.ejb.Local;
import entity.Person;
@Local
public interface PersonService {
    public Person getPersonByID(int id);
}

由ejb 实现

package ejb;
import javax.ejb.Stateless;
import javax.persistence.*;
import entity.*;
@Stateless(mappedName="PersonServiceBean")
public class PersonServiceBean implements PersonService {
    //Pass persistence unit to entity manager
    @PersistenceContext(unitName = "reporting")
    private EntityManager entityManager;
    public Person getPersonByID(int id) {
        return entityManager.find(Person.class, id);
    }
}

上面的ejb从这个实体中读取

package entity;
import java.io.Serializable;
import javax.persistence.*;

/**
* The persistent class for the person database table.
* 
*/
@Entity
@NamedQuery(name="Person.findAll", query="SELECT p FROM Person p")
public class Person implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    private int personID;
    private String emails;
    private String firstNames;
    private int organizationID;
    private int researchCategoryID;
    private int researchGroupID;
    private String surname;
    public Person() {
    }
    public int getPersonID() {
        return this.personID;
    }
    public void setPersonID(int personID) {
        this.personID = personID;
    }
    public String getEmails() {
        return this.emails;
    }
    public void setEmails(String emails) {
        this.emails = emails;
    }
    public String getFirstNames() {
        return this.firstNames;
    }
    public void setFirstNames(String firstNames) {
        this.firstNames = firstNames;
    }
    public int getOrganizationID() {
        return this.organizationID;
    }
    public void setOrganizationID(int organizationID) {
        this.organizationID = organizationID;
    }
    public int getResearchCategoryID() {
        return this.researchCategoryID;
    }
    public void setResearchCategoryID(int researchCategoryID) {
        this.researchCategoryID = researchCategoryID;
    }
    public int getResearchGroupID() {
        return this.researchGroupID;
    }
    public void setResearchGroupID(int researchGroupID) {
        this.researchGroupID = researchGroupID;
    }
    public String getSurname() {
        return this.surname;
    }
    public void setSurname(String surname) {
        this.surname = surname;
    }
}

JPA-etity连接到一个mysql数据库，这就是persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
    <persistence-unit name="reporting" transaction-type="RESOURCE_LOCAL">
        <class>entity.Person</class>
        <properties>
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/people"/>
            <property name="javax.persistence.jdbc.user" value="root"/>
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
        </properties>
    </persistence-unit>
</persistence>

我有一个充当客户端的Main类

import javax.naming.InitialContext;
import javax.naming.NamingException;
import ejb.*;
public class Main {
    public static void main(String[] args) throws NamingException {
        InitialContext ic = new InitialContext();
        PersonService service = (PersonService)ic.lookup("PersonServiceBean");
        entity.Person p = service.getPersonByID(1);
        System.out.println(p.getFirstNames());
    }
}

我正在使用EclipseLink，我不确定我在使用哪个应用程序服务器，如果我正在使用的话。如果Eclipse也有帮助的话，我正在使用它。如果我尝试运行应用程序，我会得到javax.naming.NoInitialContextException异常

Exception in thread "main" javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file: java.naming.factory.initial at javax.naming.spi.NamingManager.getInitialContext(Unknown Source) at javax.naming.InitialContext.getDefaultInitCtx(Unknown Source) at javax.naming.InitialContext.getURLOrDefaultInitCtx(Unknown Source) at javax.naming.InitialContext.lookup(Unknown Source) at Main.main(Main.java:18)

否则我如何从Main访问EJB？

Answer 1

JavaBeans that are running within the container pass their credentials within the InitialContext, which is created to look up the remote EJBs. 
To pass JNDI properties within the Hashtable environment, set them as shown below: 
Hashtable env = new Hashtable(); 
env.put("java.naming.provider.url", "ormi://localhost/ejbexample"); 
env.put("java.naming.factory.initial", 
      "com.evermind.server.ApplicationClientInitialContextFactory"); 
env.put(Context.SECURITY_PRINCIPAL, "guest"); 
env.put(Context.SECURITY_CREDENTIALS, "welcome"); 
Context ic = new InitialContext (env); 
Object homeObject = ic.lookup("java:comp/env/employeeBean");
EmployeeHome empHome =
     (EmployeeHome) PortableRemoteObject.narrow(homeObject,
                                                   EmployeeHome.class);