Jakarta ee servlet项目中的HttpSession CDI注入

我的学习计划有问题。我有一个带有一个servlet的简单项目，我需要一些具有不同作用域的CDIBean。这一部分非常简单，但我必须能够将HttpSession注入到每个CDIBean中。为了解决这个问题，我让ServletRequestListener获取HttpServletRequest对象，我将这个对象存储在ThreadLocal对象中的应用程序作用域bean中，在这个bean中，我从存储的HttpServletRequest中获得了HttpSession对象的producer方法。之后，我可以将HttpSession注入任何CDIBean，会话范围的bean除外。会话在会话初始化之后被正确地注入该bean，但是对于同一会话中的第二个请求，我有空指针异常，因为会话bean是在RequestInitialized方法之前创建（或反序列化）的，并且我的生产者返回空值，根据stacktrace，这是非法的

以下是一个会话中第二个请求的stacktrace：

    org.jboss.weld.exceptions.IllegalProductException: WELD-000052 Cannot return null from a non-dependent producer method:  [method] @Produces @RequestScoped public pl.lab2.cdi.producers.SessionObjectsProducer.getSession()
    org.jboss.weld.bean.AbstractProducerBean.checkReturnValue(AbstractProducerBean.java:217)
    org.jboss.weld.bean.AbstractProducerBean.create(AbstractProducerBean.java:300)
    org.jboss.weld.context.AbstractContext.get(AbstractContext.java:107)
    org.jboss.weld.bean.proxy.ContextBeanInstance.getInstance(ContextBeanInstance.java:90)
    org.jboss.weld.bean.proxy.ProxyMethodHandler.invoke(ProxyMethodHandler.java:104)
    org.jboss.weld.proxies.HttpSession$776413422$Proxy$_$$_WeldClientProxy.getId(HttpSession$776413422$Proxy$_$$_WeldClientProxy.java)
    pl.lab2.bean.SessionBean.toString(SessionBean.java:31)
    java.lang.String.valueOf(String.java:2854)
    java.lang.StringBuilder.append(StringBuilder.java:128)
    org.jboss.weld.context.SerializableContextualInstanceImpl.toString(SerializableContextualInstanceImpl.java:60)
    java.lang.String.valueOf(String.java:2854)
    java.lang.StringBuilder.append(StringBuilder.java:128)
    org.jboss.weld.context.beanstore.AttributeBeanStore.attach(AttributeBeanStore.java:109)
    org.jboss.weld.context.AbstractBoundContext.activate(AbstractBoundContext.java:66)
    org.jboss.weld.servlet.WeldListener.requestInitialized(WeldListener.java:141)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930)
    java.lang.Thread.run(Thread.java:724)

资料来源：

听众

package pl.lab2.servlet;

import org.apache.log4j.Logger;
import pl.lab2.cdi.BeanManagerHelper;
import pl.lab2.servlet.events.literal.*;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;

public class ServletListener implements ServletRequestListener {
    private static final Logger log = Logger.getLogger(ServletListener.class);

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        log.info("request destroyed event");
        BeanManagerHelper.getBeanManagerByJNDI().fireEvent((HttpServletRequest) sre.getServletRequest(), DestroyedLiteral.INSTANCE);
    }

    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        log.info("request initialized event");
        BeanManagerHelper.getBeanManagerByJNDI().fireEvent((HttpServletRequest) sre.getServletRequest(), InitializedLiteral.INSTANCE);
    }
}

持有者

package pl.lab2.servlet;

import org.apache.log4j.Logger;
import pl.lab2.servlet.events.Destroyed;
import pl.lab2.servlet.events.Initialized;

import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.event.Observes;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

@ApplicationScoped
public class ServletObjectHolder {
    private static final Logger log = Logger.getLogger(ServletObjectHolder.class);
    private final ThreadLocal<HttpServletRequest> threadRequest = new ThreadLocal<HttpServletRequest>();

    public HttpSession getSession() {
        log.info("get session");
        if (threadRequest.get() != null) {
            return threadRequest.get().getSession();
        }
        return null;
    }

    public void servletRequestInitialized(@Observes @Initialized final HttpServletRequest request) {
        log.info("receive request initialization");
        threadRequest.set(request);
    }

    public void servletRequestDestroyed(@Observes @Destroyed final HttpServletRequest request) {
        log.info("receive request destroyed");
        threadRequest.set(null);
    }
}

会话bean

package pl.lab2.bean;

import javax.enterprise.context.SessionScoped;
import javax.inject.Inject;
import javax.inject.Named;
import javax.servlet.http.HttpSession;
import java.io.Serializable;

@SessionScoped
@Named
public class SessionBean implements Serializable {
    private String name;
    @Inject
    private HttpSession session;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "SessionBean{" +
                "name='" + name + "', " +
                "sessionId='" + session.getId() + "'" +
                '}';
    }
}

和servlet：

package pl.lab2.servlet;

import org.apache.log4j.Logger;
import org.jboss.weld.context.ConversationContext;
import org.jboss.weld.context.http.Http;
import pl.lab2.bean.ApplicationBean;
import pl.lab2.bean.ConversationBean;
import pl.lab2.bean.RequestBean;
import pl.lab2.bean.SessionBean;
import pl.lab2.cdi.producers.SessionObjectsProducer;

import javax.enterprise.context.Conversation;
import javax.inject.Inject;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class ServletDispatcher extends HttpServlet {
    private static final Logger log = Logger.getLogger(ServletDispatcher.class);
    @Inject
    private ApplicationBean applicationBean;
    @Inject
    private SessionBean sessionBean;
    @Inject
    private ConversationBean conversationBean;
    @Inject
    private RequestBean requestBean;
    @Inject
    private Conversation conversation;
    @Inject
    @Http
    private ConversationContext conversationContext;
    @Inject
    private SessionObjectsProducer sessionObjectsProducer;

    @Override
    public void init() throws ServletException {
        super.init();
        conversationContext.setParameterName("cId");
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {
        this.request(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {
        this.request(request, response);
    }

    private void request(HttpServletRequest request, HttpServletResponse response) throws IOException {
        log.info("request started in session " + request.getSession().getId());
        String cid = request.getParameter(conversationContext.getParameterName());
        if (cid != null) {
            conversationContext.activate(cid);
        } else {
            conversationContext.activate();
        }

        takeActions(request);
        updateData(request);
        printState(response.getWriter(), request);
    }

    private void printState(PrintWriter writer, HttpServletRequest request) {
        writer.print("<div>");
        writer.print("<div>Beans:</div>");
        writer.print(applicationBean.toString() + "<br />");
        writer.print(sessionBean.toString() + "<br />");
        writer.print(conversationBean.toString() + "<br />");
        writer.print(requestBean.toString() + "<br />");
        writer.print("</div>");
        writer.print("<div>");
        writer.print("<div>Data:</div>");
        writer.print("session id: " + request.getSession().getId() + "<br />");
        writer.print("conversation id: " + conversation.getId() + "<br />");
        writer.print("</div>");
    }

    private void takeActions(HttpServletRequest request) {
        if ("begin".equals(request.getParameter("conversationState"))) conversation.begin();
        else if ("end".equals(request.getParameter("conversationState"))) conversation.end();
    }

    private void updateData(HttpServletRequest request) {
        if (request.getParameter("application") != null) {
            applicationBean.setName(request.getParameter("application"));
        }
        if (request.getParameter("session") != null) {
            sessionBean.setName(request.getParameter("session"));
        }
        if (request.getParameter("conversation") != null) {
            conversationBean.setName(request.getParameter("conversation"));
        }
        if (request.getParameter("request") != null) {
            requestBean.setName(request.getParameter("request"));
        }
    }
}

包pl.lab2.servlet；
导入org.apache.log4j.Logger；
导入org.jboss.weld.context.ConversationContext；
导入org.jboss.weld.context.http.http；
导入pl.lab2.bean.ApplicationBean；
导入pl.lab2.bean.ConversationBean；
导入pl.lab2.bean.RequestBean；
导入pl.lab2.bean.SessionBean；
导入pl.lab2.cdi.producer.SessionObjectsProducer；
导入javax.enterprise.context.Conversation；
导入javax.inject.inject；
导入javax.servlet.ServletException；
导入javax.servlet.http.HttpServlet；
导入javax.servlet.http.HttpServletRequest；
导入javax.servlet.http.HttpServletResponse；
导入java.io.IOException；
导入java.io.PrintWriter；
公共类ServletDispatcher扩展了HttpServlet{
私有静态最终记录器log=Logger.getLogger（ServletDispatcher.class）；
@注入
私有应用程序bean应用程序bean；
@注入
私有SessionBean SessionBean；
@注入
私有会话bean会话bean；
@注入
私有请求bean请求bean；
@注入
私人谈话；
@注入
@Http
私人会话语境；
@注入
私有会话对象制作者会话对象制作者；
@凌驾
public void init（）引发ServletException{
super.init（）；
setParameterName（“cId”）；
}
@凌驾
受保护的void doGet（HttpServletRequest请求、HttpServletResponse响应）抛出ServletException，
IOException{
这个。请求（请求，响应）；
}
@凌驾
受保护的void doPost（HttpServletRequest请求、HttpServletResponse响应）引发ServletException，
IOException{
这个。请求（请求，响应）；
}
私有void请求（HttpServletRequest请求、HttpServletResponse响应）引发IOException{
log.info（“请求在会话中启动”+request.getSession（）.getId（））；
字符串cid=request.getParameter（conversationContext.getParameterName（））；
如果（cid！=null）{
会话上下文激活（cid）；
}否则{
activate（）；
}
采取行动（请求）；
更新数据（请求）；
printState（response.getWriter（），request）；
}
私有void printState（PrintWriter编写器，HttpServletRequest）{
作者：印刷体（“”）；
作者。印刷（“豆：”）；
print（applicationBean.toString（）+“
”；
print（sessionBean.toString（）+“
”）；
writer.print（conversationBean.toString（）+“
”）；
writer.print（requestBean.toString（）+“
”）；
作者：印刷体（“”）；
作者：印刷体（“”）；
writer.print（“数据：”）；
writer.print（“会话id:+request.getSession（）.getId（）+”
）；
writer.print（“会话id:+conversation.getId（）+”
）；
作者：印刷体（“”）；
}
私有无效操作（HttpServletRequest）{
if（“begin”.equals（request.getParameter（“conversationState”））conversation.begin（）；
else if（“end”.equals（request.getParameter（“conversationState”））conversation.end（）；
}
私有void updateData（HttpServletRequest）{
if（request.getParameter（“应用程序”）！=null）{
setName（request.getParameter（“应用”）；
}
if（request.getParameter（“会话”）！=null）{
setName（request.getParameter（“session”）；
}
if（request.getParameter（“对话”）！=null）{
setName（request.getParameter（“conversation”）；
}
if（request.getParameter（“request”）！=null）{
setName（request.getParameter（“request”）；
}
}
}

为此，我使用来自github的seam/servlet源代码作为示例

---

我已经上传了我当前的代码，只需构建，作为7.1.1.Final部署在JBoss上，转到localhost:8080/lab2，按F5两次，您就会看到问题。

简单的操作下面的代码可以满足您的需要，并且可以很好地工作：

import javax.enterprise.context.RequestScoped;
import javax.enterprise.inject.Produces;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

// NOTE: this produces a request scoped session object because that's what the OP seems to want
@WebListener
public class SessionProducer implements ServletRequestListener {

    private static ThreadLocal<HttpSession> SESSIONS = new ThreadLocal<>();

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        SESSIONS.remove();
    }

    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        SESSIONS.set(HttpServletRequest.class.cast(sre.getServletRequest()).getSession());
    }

    @Produces @RequestScoped
    protected HttpSession getSession() {
        return SESSIONS.get();
    }

}

import javax.enterprise.context.requestscope；
导入javax.enterprise.inject.products；
导入javax.servlet.ServletRequestEvent；
导入javax.servlet.ServletRequestListener；
导入javax.servlet.annotation.WebListener；
导入javax.servlet.http.HttpServletRequest；
导入javax.servlet.http.HttpSession；
//注意：这会产生一个请求范围的会话对象，因为OP似乎想要这样
@网络监听器
公共类SessionProducer实现ServletRequestListener{
私有静态ThreadLocal会话=新ThreadLocal（）；
@凌驾
公共无效请求已销毁（ServletRequestEvent sre）{
SESSIONS.remove（）；
}
@凌驾
public void requestInitialized（ServletRequestEvent sre）{
SESSIONS.set（HttpServletRequest.class.cast（sre.getServletRequest（））.getSession（））；
import javax.enterprise.context.RequestScoped;
import javax.enterprise.inject.Produces;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

// NOTE: this produces a request scoped session object because that's what the OP seems to want
@WebListener
public class SessionProducer implements ServletRequestListener {

    private static ThreadLocal<HttpSession> SESSIONS = new ThreadLocal<>();

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        SESSIONS.remove();
    }

    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        SESSIONS.set(HttpServletRequest.class.cast(sre.getServletRequest()).getSession());
    }

    @Produces @RequestScoped
    protected HttpSession getSession() {
        return SESSIONS.get();
    }

}