如何在命令按钮操作中使用托管 bean 属性

Question

如何设置动作：

<h:commandButton id="submit" value="Submit" action="#{user.nav}"/>

所以 action 是从 User bean 返回的 String？

login.xhtml引起的问题：

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
                xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
                xmlns:h="http://xmlns.jcp.org/jsf/html"
                xmlns:f="http://xmlns.jcp.org/jsf/core">
    <h:form>
        <h2>
            Hi, my name is #{user.myName} #{user.myId}. 
            What's your name?
        </h2>
        <p><h:inputText id="user"
                        title="enter your name"
                        value="#{user.user}">
            </h:inputText>
            <h:commandButton id="submit" value="Submit"
                             action="#{user.nav}"/>
        </p>
        <h:message showSummary="true" showDetail="false"
                   style="color: #d20005;
                   font-family: 'New Century Schoolbook', serif;
                   font-style: oblique;
                   text-decoration: overline"
                   id="errors1"
                   for="userNo"/>
    </h:form>
</ui:composition>

glassfish 日志：

Warning:   Unable to find component with ID userNo in view.
Info:   net.bounceme.doge.facelets.User setUser..   jklhjkghk
Warning:   #{user.nav}: javax.el.MethodNotFoundException: /WEB-INF/includes/login.xhtml @17,52 action="#{user.nav}": Method not found: net.bounceme.doge.facelets.User@6c21eb05.nav()
javax.faces.FacesException: #{user.nav}: javax.el.MethodNotFoundException: /WEB-INF/includes/login.xhtml @17,52 action="#{user.nav}": Method not found: net.bounceme.doge.facelets.User@6c21eb05.nav()
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:110)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
    at org.glassfish.grizzly.filterchain.ExecutorResolver.execute(ExecutorResolver.java:119)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access0(WorkerThreadIOStrategy.java:56)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javax.faces.el.MethodNotFoundException: javax.el.MethodNotFoundException: /WEB-INF/includes/login.xhtml @17,52 action="#{user.nav}": Method not found: net.bounceme.doge.facelets.User@6c21eb05.nav()
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:91)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
    ... 35 more
Caused by: javax.el.MethodNotFoundException: /WEB-INF/includes/login.xhtml @17,52 action="#{user.nav}": Method not found: net.bounceme.doge.facelets.User@6c21eb05.nav()
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:109)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
    ... 36 more

Warning:   StandardWrapperValve[Faces Servlet]: Servlet.service() for servlet Faces Servlet threw exception
javax.el.MethodNotFoundException: /WEB-INF/includes/login.xhtml @17,52 action="#{user.nav}": Method not found: net.bounceme.doge.facelets.User@6c21eb05.nav()
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:109)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
    at org.glassfish.grizzly.filterchain.ExecutorResolver.execute(ExecutorResolver.java:119)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access0(WorkerThreadIOStrategy.java:56)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

<h:commandButton action> requires 是方法表达式，不是值表达式。异常会准确地告诉您这一点。除了破解 JSF 源代码之外，没有什么可以改变这一点。

您有 2 个选择：

将其修复为真正的动作方法，而不是属性。
```
public String nav() {
    return "some";
}
```
或者，直接调用 getter。
```
action="#{user.getNav()}"
```
这只会导致错误和混乱的代码。

如何在命令按钮操作中使用托管 bean 属性

How to use managed bean property in command button action

jsf

facelets

commandbutton