解决JAX-RS资源中EJB注入失败问题：深入理解非托管组件与JNDI查找

import javax.ejb.EJB;
import javax.ws.rs.FormParam;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

@Path("")
public class Service  
{
    @EJB
    UserSessionBeanLocal userBean; // 此处注入可能失败

    @POST
    @Produces(MediaType.APPLICATION_JSON)
    @Path("register")
    public Response register(@FormParam("userName") final String name, @FormParam("userPassword") final String pass, @FormParam("userEmail")  String email)
    {
        // 当userBean为null时，调用其方法将抛出NullPointerException
        if (userBean.isUserPresent(email)) 
            return Response.ok("Email already registered!!").build();
        userBean.addUser(new User(name, email, pass));
        return Response.ok("Registered!!").build();
    }
}

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ws.rs.FormParam;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

@Path("")
public class Service  
{
    // 移除 @EJB 注解，因为我们将手动查找
    // UserSessionBeanLocal userBean; 

    @POST
    @Produces(MediaType.APPLICATION_JSON)
    @Path("register")
    public Response register(@FormParam("userName") final String name, @FormParam("userPassword") final String pass, @FormParam("userEmail") String email) 
    {
        UserSessionBeanLocal userBean = null;
        try 
        {
            // 1. 创建InitialContext实例
            InitialContext ic = new InitialContext();
            // 2. 通过JNDI名称查找EJB
            // JNDI名称格式通常为 "java:global/应用程序名称/模块名称/EJB名称!EJB本地接口全限定名"
            // 根据日志 "java