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我正在使用 Primefaces 标签库开发一个应用程序。

到目前为止，我已经从他们的官方网站上复制了一些示例，除了使用 RequestContext.getCurrentInstance() 方法的任何内容之外，所有示例似乎都有效。它要么每次都返回 null，导致 Tomcat 抛出 NullPointer 异常，要么永远挂起，从不返回任何内容。

这是我的代码（挂起的情况）：

GlobalCounterBean.java

package org.primefaces.examples.view;

import java.io.Serializable;
import org.primefaces.context.RequestContext;

public class GlobalCounterBean implements Serializable{

    private int count;

    public int getCount() {
    return count;
    }

    public void setCount(int count) {
    this.count = count;
    }

    public synchronized void increment() {
    count++;
    System.out.println("aaaa");
        RequestContext.getCurrentInstance().push("counter", count);
    }
}

测试.xhtml：

<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:h="http://java.sun.com/jsf/html"
        xmlns:f="http://java.sun.com/jsf/core"
        xmlns:p="http://primefaces.org/ui">
    <h:head>
    </h:head>   
    <h:body>    

        <p:spinner />   

        <h:form>
    <h:outputText value="#{globalCounter.count}" styleClass="ui-widget display" />

    <br />

    <p:commandButton value="Click" actionListener="#{globalCounter.increment}" />
</h:form>

<p:push onmessage="handleMessage" channel="counter" />

<script type="text/javascript">
    function handleMessage(evt, data) {
            $('.display').html(data);
    }
</script>


    </h:body>
</html>

以下是它返回 null 时的代码（所有文件都在同一个项目中）：

聊天控制器.java：

    package org.primefaces.examples.view;

    import java.io.Serializable;
    import java.util.HashSet;
    import java.util.Set;

    import javax.faces.application.FacesMessage;
    import javax.faces.bean.ApplicationScoped;
    import javax.faces.bean.ManagedBean;
    import javax.faces.context.FacesContext;
    import javax.faces.event.ActionEvent;

    import org.primefaces.context.RequestContext;


    public class ChatController implements Serializable {

        private final static String CHANNEL = "chat";

        private String message;

        private String username;

        private boolean loggedIn;

        private Set<String> users = new HashSet<String>();

        public String getMessage() {
            return message;
        }
        public void setMessage(String message) {
            this.message = message;
        }

        public String getUsername() {
            return username;
        }
        public void setUsername(String username) {
            this.username = username;
        }

        public boolean isLoggedIn() {
            return loggedIn;
        }
        public void setLoggedIn(boolean loggedIn) {
            this.loggedIn = loggedIn;
        }

        public void send() {
            RequestContext.getCurrentInstance().push(CHANNEL, username + ": "+  message);

            message = null;
        }

        public void login() {

            RequestContext requestContext = RequestContext.getCurrentInstance();

            if(users.contains(username)) {
                loggedIn = false;
                FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, "Username taken", "Try with another username."));

                requestContext.addPartialUpdateTarget("growl");
            }
            else {
                users.add(username);
                loggedIn = true;

                requestContext.push(CHANNEL, username + " joined the channel.");
            }
        }

        public void disconnect() {
            RequestContext.getCurrentInstance().push(CHANNEL, username + " has left the channel.");
            loggedIn = false;
            username = null;
        }
    }

聊天.xhtml

        <html xmlns="http://www.w3.org/1999/xhtml"
            xmlns:h="http://java.sun.com/jsf/html"
            xmlns:f="http://java.sun.com/jsf/core"
            xmlns:p="http://primefaces.org/ui">

        <head>
        <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
        <title>Insert title here</title>
        </head>
        <body>
        <f:view>
        <p:growl id="growl" showDetail="true" />

        <h:form>

            <p:fieldset id="container" legend="PrimeChat">

                <h:panelGroup rendered="#{chatController.loggedIn}" >
                    <p:outputPanel layout="block" style="width:600px;height:200px;overflow:auto" 
                               styleClass="chatroom" />
                    <p:spinner />
                    <p:separator />

                    <p:inputText value="#{chatController.message}" styleClass="messageInput" />
                    <p:spacer width="5" />
                    <p:commandButton value="Send" actionListener="#{chatController.send}" global="false" oncomplete="$('.messageInput').val('').focus()"/>
                    <p:spacer width="5" />
                    <p:commandButton value="Disconnect" actionListener="#{chatController.disconnect}" global="false" 
                                        oncomplete="chatAgent.close()" update="container" />
                </h:panelGroup>

                <h:panelGroup rendered="#{not chatController.loggedIn}" >
                    Username: <p:inputText value="#{chatController.username}" />

                    <p:spacer width="5" />
                    <p:commandButton value="Login" actionListener="#{chatController.login}" update="container" 
                                     icon="ui-icon-person"/>
                </h:panelGroup>

            </p:fieldset>

        </h:form>

        <p:push onmessage="handleMessage" channel="chat" widgetVar="chatAgent" />

        <script type="text/javascript">
            function handleMessage(evt, data) {
                var chatContent = $('.chatContent');
                chatContent.append(data + '<br />');

                //keep scroll
                chatContent.scrollTop(chatContent.height());
            }
        </script>
        <script type="text/javascript">
        function handleComplete(xhr, status, args) {
            if(args.validationFailed) {
                PrimeFaces.debug("Validation Failed");
            } 
            else {
                PrimeFaces.debug("Save:" + args.saved);
                PrimeFaces.debug("FirstName: " + args.user.firstname + ", Lastname: " + args.user.lastname); 
            }
        }
        </script>

        </f:view>
        </body>
        </html>

面孔-config.xml：

    <?xml version="1.0" encoding="utf-8"?>
    <faces-config version="2.0" xmlns="http://java.sun.com/xml/ns/javaee"
     xmlns:xi="http://www.w3.org/2001/XInclude"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd">
     <managed-bean eager="true">
      <managed-bean-name>chatController</managed-bean-name>
      <managed-bean-class>org.primefaces.examples.view.ChatController</managed-bean-class>
      <managed-bean-scope>request</managed-bean-scope>
     </managed-bean>
     <managed-bean>
      <managed-bean-name>globalCounter</managed-bean-name>
      <managed-bean-class>org.primefaces.examples.view.GlobalCounterBean</managed-bean-class>
      <managed-bean-scope>application</managed-bean-scope>
     </managed-bean>
     <!--
        No ManagedBean declarations here as we are using @ManagedBean Annotations.
        -->
    </faces-config>

网页.xml：

        <?xml version="1.0" encoding="UTF-8"?>
        <web-app version="2.5"
            xmlns="http://java.sun.com/xml/ns/javaee"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" >

            <welcome-file-list>
                <welcome-file>index.jsp</welcome-file>
            </welcome-file-list>

            <servlet>
                <servlet-name>Faces Servlet</servlet-name>
                <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
                <load-on-startup>1</load-on-startup>
            </servlet>

            <servlet-mapping>
                <servlet-name>Faces Servlet</servlet-name>
                <url-pattern>*.xhtml</url-pattern>
            </servlet-mapping>

        </web-app>

这是tomcat控制台中抛出的异常：

                        2012-05-27 19:16:25 com.sun.faces.context.ExceptionHandlerImpl log
            SEVERE: JSF1073: javax.faces.event.AbortProcessingException caught during processing of INVOKE_APPLICATION 5 : UIComponent-ClientId=j_idt2:j_idt16, Message=java.lang.NullPointerException
            2012-05-27 19:16:25 com.sun.faces.context.ExceptionHandlerImpl log
            SEVERE: java.lang.NullPointerException
            javax.faces.event.AbortProcessingException: java.lang.NullPointerException
                at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:178)
                at javax.faces.event.ActionEvent.processListener(ActionEvent.java:84)
                at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:773)
                at javax.faces.component.UICommand.broadcast(UICommand.java:296)
                at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:781)
                at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1246)
                at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:77)
                at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
                at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:114)
                at javax.faces.webapp.FacesServlet.service(FacesServlet.java:308)
                at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
                at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
                at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
                at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
                at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
                at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
                at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
                at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
                at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
                at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
                at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
                at java.lang.Thread.run(Thread.java:680)
            Caused by: java.lang.NullPointerException
                at org.primefaces.examples.view.ChatController.login(ChatController.java:69)
                at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
                at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
                at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
                at java.lang.reflect.Method.invoke(Method.java:597)
                at org.apache.el.parser.AstValue.invoke(AstValue.java:191)
                at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
                at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:149)
                ... 21 more
4

1 回答 1

2

您web.xml缺少 PrimeFaces Push 设置的“URL 配置”部分。

正如我对您上一个问题的回答中提到的，PrimeFaces Push 的安装详细信息在 PrimeFaces User's Guide的第 6 章中进行了概述。这是您缺少的步骤的相关性摘录：

6.1 设置

推送服务器

PrimeFaces Push 使用 servlet 作为调度程序。此 servlet 应该与 JSF 应用程序位于不同的应用程序中，并且目前只能部署在 jetty 服务器上。

<servlet>
    <servlet-name>Push Servlet</servlet-name>
    <servlet-class>org.primefaces.push.PushServlet</servlet-class>
    <load-on-startup>1</load-on-startup> 
    <init-param>
        <param-name>channels</param-name>
        <param-value>chat,counter</param-value>
    </init-param>
</servlet>
<servlet-mapping>
    <servlet-name>Push Servlet</servlet-name>
    <url-pattern>/prime-push/*</url-pattern>
</servlet-mapping>

频道配置定义了推送服务器可以发布到的主题名称。

网址配置

JSF 应用程序需要定义推送服务器 url 来发送消息。

<context-param>
    <param-name>primefaces.PUSH_SERVER_URL</param-name>
    <param-value>ws://url_to_push_server</param-value>
</context-param>
于 2012-05-27T18:03:38.093 回答