FacesConverter的用例
[英]use case for FacesConverter
问题描述
Referencing a previous question of mine, why is the @PostConstruct method not runnable? 
引用我的上一个问题 ，为什么@PostConstruct方法不能运行？
glassfish gives: 玻璃鱼给：
INFO: MessageBean..
INFO: MessageBean.getModel..
INFO: SingletonNNTP.getMessages..
INFO: MessageBean.getModel..
INFO: SingletonNNTP.getMessages..
INFO: SingletonNNTP.setIndex..2,205
INFO: SingletonNNTP.setIndex..2,205
INFO: SingletonNNTP.setIndex..2,206
INFO: SingletonNNTP.setIndex..2,206
INFO: SingletonNNTP.setIndex..2,207
INFO: SingletonNNTP.setIndex..2,207
INFO: SingletonNNTP.setIndex..2,208
INFO: SingletonNNTP.setIndex..2,208
INFO: SingletonNNTP.setIndex..2,209
INFO: SingletonNNTP.setIndex..2,209
INFO: SingletonNNTP.setIndex..2,210
INFO: SingletonNNTP.setIndex..2,210
INFO: SingletonNNTP.setIndex..2,211
INFO: SingletonNNTP.setIndex..2,211
INFO: SingletonNNTP.setIndex..2,212
INFO: SingletonNNTP.setIndex..2,212
INFO: SingletonNNTP.setIndex..2,213
INFO: SingletonNNTP.setIndex..2,213
INFO: SingletonNNTP.setIndex..2,214
INFO: SingletonNNTP.setIndex..2,214
INFO: SingletonNNTP.setIndex..2,215
INFO: SingletonNNTP.setIndex..2,215
INFO: MessageBean.getModel..
INFO: SingletonNNTP.getMessages..
INFO: Detail..
WARNING: /foo/detail.xhtml @9,67 value="#{detail.id}": org.jboss.weld.exceptions.WeldException: WELD-000049 Unable to invoke [method] @PostConstruct public net.bounceme.dur.nntp.Detail.configBean() on net.bounceme.dur.nntp.Detail@c8e43a
javax.el.ELException: /foo/detail.xhtml @9,67 value="#{detail.id}": org.jboss.weld.exceptions.WeldException: WELD-000049 Unable to invoke [method] @PostConstruct public net.bounceme.dur.nntp.Detail.configBean() on net.bounceme.dur.nntp.Detail@c8e43a
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UIOutput.getValue(UIOutput.java:169)
at javax.faces.component.UIInput.validate(UIInput.java:972)
at javax.faces.component.UIInput.executeValidate(UIInput.java:1233)
at javax.faces.component.UIInput.processValidators(UIInput.java:698)
at javax.faces.component.UIViewParameter.processValidators(UIViewParameter.java:273)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1172)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
Caused by: org.jboss.weld.exceptions.WeldException: WELD-000049 Unable to invoke [method] @PostConstruct public net.bounceme.dur.nntp.Detail.configBean() on net.bounceme.dur.nntp.Detail@c8e43a
at org.jboss.weld.bean.AbstractClassBean.defaultPostConstruct(AbstractClassBean.java:508)
at org.jboss.weld.bean.ManagedBean$ManagedBeanInjectionTarget.postConstruct(ManagedBean.java:174)
at org.jboss.weld.bean.ManagedBean.create(ManagedBean.java:291)
at org.jboss.weld.context.AbstractContext.get(AbstractContext.java:107)
at org.jboss.weld.bean.proxy.ContextBeanInstance.getInstance(ContextBeanInstance.java:90)
at org.jboss.weld.bean.proxy.ProxyMethodHandler.invoke(ProxyMethodHandler.java:79)
at net.bounceme.dur.nntp.Detail$Proxy$_$$_WeldClientProxy.getId(Detail$Proxy$_$$_WeldClientProxy.java)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:363)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at com.sun.el.parser.AstValue.getValue(AstValue.java:138)
at com.sun.el.parser.AstValue.getValue(AstValue.java:183)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:224)
at org.jboss.weld.el.WeldValueExpression.getValue(WeldValueExpression.java:50)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
... 38 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.jboss.weld.util.reflection.SecureReflections$13.work(SecureReflections.java:264)
at org.jboss.weld.util.reflection.SecureReflectionAccess.run(SecureReflectionAccess.java:52)
at org.jboss.weld.util.reflection.SecureReflectionAccess.runAsInvocation(SecureReflectionAccess.java:137)
at org.jboss.weld.util.reflection.SecureReflections.invoke(SecureReflections.java:260)
at org.jboss.weld.introspector.jlr.WeldMethodImpl.invoke(WeldMethodImpl.java:174)
at org.jboss.weld.bean.AbstractClassBean.defaultPostConstruct(AbstractClassBean.java:506)
... 56 more
Caused by: java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:454)
at java.lang.Integer.parseInt(Integer.java:527)
at net.bounceme.dur.nntp.Detail.configBean(Detail.java:29)
... 66 more
INFO: Detail..
I was getting better output earlier, in which the bean was instantiated but with default values and not getting the URL parameters in time, so that some fields were populated and some not. 之前，我得到了更好的输出，其中实例化了bean，但是具有默认值，并且没有及时获取URL参数，因此填充了某些字段，而没有填充。
If my Java code is unclear, please let me know in what way it's unclear. 如果我的Java代码不清楚，请以不清楚的方式通知我。 I know of no better way to parse String to Integer, for example. 例如，我知道没有更好的方法将String解析为Integer。 See comments here . 在这里查看评论。
package net.bounceme.dur.nntp;
import java.io.Serializable;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.PostConstruct;
import javax.enterprise.context.ConversationScoped;
import javax.inject.Named;
import javax.mail.Message;
@Named
@ConversationScoped
public class Detail implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger LOG = Logger.getLogger(Detail.class.getName());
private String id = null;
private Message message = null;
private SingletonNNTP nntp = SingletonNNTP.INSTANCE;
private int forward = 0;
private int back = 0;
public Detail() {
LOG.info("Detail..");
}
@PostConstruct
public void configBean() {
int intId = Integer.parseInt(id);
try {
nntp.setIndex(intId);
message = nntp.getMessage();
} catch (Exception ex) {
LOG.info("Detail.configBean..failed to set message");
}
setForward(intId + 1);
setBack(intId - 1);
}
public Message getMessage() throws Exception {
LOG.info("Detail.getMessage.." + getId());
return message;
}
public void setMessage(Message message) {
LOG.info("Detail.setMessage..");
this.message = message;
}
public String getId() throws Exception {
LOG.info("Detail.getId.." + id);
if (id == null) { //should never be null, should get from URL as param
LOG.info("..setting default id");
id = String.valueOf(2000);
}
return id;
}
public void setId(String id) throws Exception {
LOG.info("Detail.setId.." + id);
this.id = id;
}
public int getForward() throws Exception {
LOG.info("Detail.getForward.." + forward);
return forward;
}
public void setForward(int forward) {
LOG.info("Detail.setForward.." + forward);
this.forward = forward;
}
public int getBack() throws Exception {
LOG.info("Detail.setBack.." + back);
return back;
}
public void setBack(int back) {
LOG.info("Detail.setBack.." + back);
this.back = back;
}
}
and the view: 和视图：
<?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:ui="http://java.sun.com/jsf/facelets"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html">
<body>
<f:metadata>
<f:viewParam name="id" id="id" value="#{detail.id}" />
</f:metadata>
<ui:composition template="./complexTemplate.xhtml">
<ui:define name="top">
<div style="float: left">
<h:link value="back" outcome="detail" includeViewParams="true">
<f:param name="id" value="#{detail.back}"/>
</h:link>
</div>
<div style="float: right">
<h:link value="forward" outcome="detail" includeViewParams="true">
<f:param name="id" value="#{detail.forward}"/>
</h:link>
</div>
<p align="center"><h:outputText value="#{detail.message.messageNumber}" /></p>
</ui:define>
<ui:define name="left">
<h:outputText value="#{detail.message.sentDate}" /><p/>
<h:outputText value="#{detail.message.subject}"/><p/>
</ui:define>
<ui:define name="right">
</ui:define>
<ui:define name="content">
<h:outputText value="#{detail.message.content}" escape="false"/>
</ui:define>
<ui:define name="bottom">
</ui:define>
</ui:composition>
</body>
</html>
My take on this is that the getter/setter methods which take URL parameters as method arguments are invoked after @PostConstruct resulting in a bean in an indeterminate state. 我对此的看法是，将@URL用作方法参数的getter / setter方法在@PostConstruct之后被调用，导致bean处于不确定状态。 The bean has been instantiated but the fields have not been initialized with values from the URL parameters. Bean已实例化，但尚未使用URL参数中的值初始化字段。 This, there's no way which I'm aware of to determine whether the bean has been initialized or not with URL parameters. 这样，我就无法确定是否已使用URL参数初始化了bean。
Previously I had output where this was clearer, but at the moment I can only generate this error. 以前，我在较清晰的地方输出了输出，但目前只能产生此错误。
For practical purposes, I've just gone and moved the contents of the @PostConstruct method to the Detail.setId(String), which at least works. 出于实际目的，我刚刚将@PostConstruct方法的内容移到了Detail.setId（String）上，该方法至少可以正常工作。 Looking at the oracle docs , I just don't see this directly covered, however the implication I draw from those docs is to use a Converter, which was also suggested previously. 查看oracle 文档 ，我只是看不到它直接涵盖的内容，但是我从这些文档中得出的含义是使用Converter，这在前面也曾提出过。
I'm more curious than likely to actually implement a Converter, as it just seems a quite complex way of doing a simple thing. 我比实际实现Converter更好奇，因为这似乎是完成一件简单事情的相当复杂的方法。 However, the "logic" in @PostConstruct rightly belongs in a Converter? 但是，@ PostConstruct中的“逻辑”正确地属于Converter吗？
The above code isn't what I'm actually using, it's just for this question, which is why the "logic" works, not in the @PostConstruct method, but instead the setId() method. 上面的代码不是我实际使用的代码，仅用于此问题，这就是为什么“逻辑”起作用的原因，而不是@PostConstruct方法而不是setId（）方法。
1 个解决方案
解决方案1
3 已采纳 2012-04-13 08:47:12
Trying to use @PostConstruct was pointless because, from what I gather, that method executes prior the CDI magic where the params are read.
Ooops, then the spec must be wrong :) Mate, your code looks like a mess and the same might be true for your project-setup? 糟糕，那么规范一定是错误的 :)伙计，您的代码看起来像一团糟，对于您的项目设置来说是否也是如此？
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