“无法到达目标，标识符'mainBean'解析为空” JSF

如何解决“无法到达目标，标识符'mainBean'解析为空” JSF

我试图再次建立Java JSF网站，并且当我单击“加载”按钮时发生此错误。

（即使用glassfish服务器和netbeans）

据我所知，我必须在bean中具有getter和setter方法，我还认为Managedbean和范围内的应用程序应该是正确的注释，这就是我使用的方法：

JDK 11 JSF 2.2 Java EE Web 7 API库

javax.faces.el.EvaluationException: javax.el.PropertyNotFoundException: /index.xhtml @15,78 action="#{mainBean.fillArrays()}": Target Unreachable,identifier 'mainBean' resolved to null
    at com.sun.faces.application.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:70)
    at com.sun.faces.application.ActionListenerImpl.getNavigationOutcome(ActionListenerImpl.java:82)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:71)
    at javax.faces.component.UICommand.broadcast(UICommand.java:222)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:847)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1395)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:58)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:76)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:177)
    at javax.faces.webapp.FacesServlet.executeLifecyle(FacesServlet.java:707)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:451)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1540)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:119)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:611)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:550)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:75)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:114)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:332)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:199)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:439)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:144)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:182)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:156)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:218)
    at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:95)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:260)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:177)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:109)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:88)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:53)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:515)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:89)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:94)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:33)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:114)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:569)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:549)
    at java.lang.Thread.run(Thread.java:748)
Caused by: javax.el.PropertyNotFoundException: /index.xhtml @15,identifier 'mainBean' resolved to null
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:67)
    at com.sun.faces.application.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:66)
    ... 38 more

我的index.xhtml

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://xmlns.jcp.org/jsf/html"
      xmlns:f="http://xmlns.jcp.org/jsf/core">
    <h:head>
        <title>Widow HS</title>
    </h:head>




    <h:body>
        <h:form>
            <h:commandButton action="#{mainBean.fillArrays()}" value="load"/>
            <h:dataTable value="#{mainBean.userarray}" var="u">  
                <h:column>  
                    <f:facet name="header">username</f:facet>  
                    <h:outputText value="#{u.username}"/>  
                </h:column>  
                <h:column>  
                    <f:facet name="header">Kills</f:facet>  
                    <h:outputText value="#{mainBean.getAllKills(u)}"/>  
                </h:column>  
                <h:column>  
                    <f:facet name="header">Deaths</f:facet>  
                    <h:outputText value="#{mainBean.getAllDeaths(u)}"/>  
                </h:column>  
            </h:dataTable> 
        </h:form>


    </h:body>
</html>

我的ManagedBean

package beans;

import java.util.ArrayList;
import javax.enterprise.context.RequestScoped;
import javax.faces.bean.ManagedBean;
import javax.inject.Named;
import model.Match;
import model.Stats;
import model.User;

@Named
@ManagedBean
@RequestScoped
public class MainBean {

    private ArrayList<User> userarray = new ArrayList();
    private ArrayList<Stats> statsarray = new ArrayList();
    private ArrayList<Match> matcharray = new ArrayList();

    public ArrayList<User> getUserarray() {
        return userarray;
    }

    public void setUserarray(ArrayList<User> userarray) {
        this.userarray = userarray;
    }

    public ArrayList<Stats> getStatsarray() {
        return statsarray;
    }

    public void setStatsarray(ArrayList<Stats> statsarray) {
        this.statsarray = statsarray;
    }

    public ArrayList<Match> getMatcharray() {
        return matcharray;
    }

    public void setMatcharray(ArrayList<Match> matcharray) {
        this.matcharray = matcharray;
    }

    public int getAllKills(User u) {
        int kills = 0;
        for (Stats stats : statsarray) {
            if (u.getDiscordId() == stats.getDiscordUserId()) {
                kills = kills + stats.getKills();
            }
        }
        return kills;
    }

    public int getAllDeaths(User u) {
        int deaths = 0;
        for (Stats stats : statsarray) {
            if (u.getDiscordId() == stats.getDiscordUserId()) {
                deaths = deaths + stats.getDeaths();
            }
        }
        return deaths;
    }

    public void fillArrays() {

        userarray = service.Service.getAllUsersFromDB();

    }

}