blocks|key|2958111|text|进程获取参数|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2958112|管理GET参数的设置、转换和验证。它类似于<h:inputText>，但用于GET参数。|offset|length|style|CODE|2958113|下面的例子|2958114|<f:metadata>
++++<f:viewParam+name="id"+value="#{bean.id}"+/>
</f:metadata>|code-block|syntax|javascript|2958115|基本上执行以下操作：|2958116|2958117|通过名称id.|unordered-list-item|2958118|Convert获取请求参数值，并在必要时进行验证(您可以像<h:inputText>)|2958119|If转换一样使用required、validator和converter属性并在其中嵌套<f:converter>和<f:validator>，验证成功后，将其设置为#{bean.id}值表示的bean属性，或者如果缺少value属性，则将其设置为名称上的请求属性，以便视图中的D19可用。<代码>H220F221|2958120|2958121|因此，当您以foo.xhtml?id=10打开页面时，就在呈现视图之前，以这种方式在bean中设置参数值10。|2958122|对于验证，下面的示例将参数设置为required="true"，并且只允许10到20之间的值。任何验证失败都将导致显示一条消息。|2958123|<f:metadata>
++++<f:viewParam+id="id"+name="id"+value="#{bean.id}"+required="true">
++++++++<f:validateLongRange+minimum="10"+maximum="20"+/>
++++</f:viewParam>
</f:metadata>
<h:message+for="id"+/>|2958124|2958125|对GET参数执行业务操作|2958126|为此，您可以使用。|2958127|<f:metadata>
++++<f:viewParam+id="id"+name="id"+value="#{bean.id}"+required="true">
++++++++<f:validateLongRange+minimum="10"+maximum="20"+/>
++++</f:viewParam>
++++<f:viewAction+action="#{bean.onload}"+/>
</f:metadata>
<h:message+for="id"+/>|2958128|使用|2958129|public+void+onload()+{
++++//+...
}|2958130|然而，<f:viewAction>是JSF2.2之后的新特性(+<f:viewParam>从JSF2.0就已经存在了)。如果你不能升级，那么你最好的选择就是使用。|2958131|<f:event+type="preRenderView"+listener="#{bean.onload}"+/>|2958132|但是，在每次请求时都会调用它。您需要显式检查请求是否不是回发：|2958133|public+void+onload()+{
++++if+(!FacesContext.getCurrentInstance().isPostback())+{
++++++++//+...
++++}
}|2958134|当您还想跳过“转换/验证失败”的情况时，请执行以下操作：|2958135|public+void+onload()+{
++++FacesContext+facesContext+=+FacesContext.getCurrentInstance();
++++if+(!facesContext.isPostback()+&&+!facesContext.isValidationFailed())+{
++++++++//+...
++++}
}|2958136|以这种方式使用<f:event>本质上是一种变通方法，这正是JSF2.2中引入<f:viewAction>的原因。|2958137|2958138|将视图参数传递给下一个视图|2958139|您可以通过将includeViewParams属性设置为true或添加includeViewParams=true请求参数来“传递”导航链接中的视图参数。|2958140|<h:link+outcome="next"+includeViewParams="true">

<h:link+outcome="next?includeViewParams=true">|2958141|在上面的<f:metadata>示例中，它基本上生成以下链接|2958142|<a+href="next.xhtml?id=10">|2958143|使用原始参数值。|2958144|这种方法只要求next.xhtml在同一个参数上也有一个<f:viewParam>，否则它不会被传递。|2958145|2958146|在JSF中使用GET表单|2958147|<f:viewParam>也可以与“普通超文本标记语言”GET表单结合使用。|2958148|<f:metadata>
++++<f:viewParam+id="query"+name="query"+value="#{bean.query}"+/>
++++<f:viewAction+action="#{bean.search}"+/>
</f:metadata>
...
<form>
++++<label+for="query">Query</label>
++++<input+type="text"+name="query"+value="#{empty+bean.query+?+param.query+:+bean.query}"+/>
++++<input+type="submit"+value="Search"+/>
++++<h:message+for="query"+/>
</form>
...
<h:dataTable+value="#{bean.results}"+var="result"+rendered="#{not+empty+bean.results}">
+++++...
</h:dataTable>|2958149|基本上使用这个@RequestScoped+bean：|2958150|private+String+query;
private+List<Result>+results;

public+void+search()+{
++++results+=+service.search(query);
}|2958151|请注意，<h:message>是用于<f:viewParam>的，而不是普通的HTML+<input+type="text">！还要注意，当#{bean.query}为空时，输入值显示为#{param.query}，因为如果不这样做，当出现验证或转换错误时，提交的值根本不会显示。请注意，这个构造对于JSF输入组件是无效的(它已经“在幕后”这样做了)。|2958152|2958153|另请参阅：|2958154|2958155|ViewParam+vs+@ManagedProperty(value+=+"#{param.id}")|2958156|Communication+in+JSF+2.0+-+Processing+GET+request+parameters|2958157|2958158|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/4888942/viewparam-vs-managedpropertyvalue-param-id|1|http://balusc.blogspot.com/2011/09/communication-in-jsf-20.html#ProcessingGETRequestParameters^0|0|L|D|0|0|0|0|0|4|2|0|T|D|0|8|8|H|9|R|9|18|D|1M|D|2B|A|32|5|0|0|6|F|1G|2|0|G|F|0|0|0|0|0|0|0|0|3|E|W|D|0|0|0|0|0|0|7|9|13|E|0|0|0|6|H|S|4|Z|M|0|0|4|C|0|0|0|7|A|S|D|0|0|0|0|D|0|0|7|E|0|0|4|B|I|D|18|J|1Y|D|2L|E|0|0|0|0|0|1G|0|0|0|1O|1|0|0^^$0|@$1|2|3|4|5|6|7|35|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|36|8|@$D|37|E|38|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|39|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|3A|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|3B|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|3C|8|@]|9|@]|A|$]]|$1|R|3|S|5|T|7|3D|8|@$D|3E|E|3F|F|G]]|9|@]|A|$]]|$1|U|3|V|5|T|7|3G|8|@$D|3H|E|3I|F|G]]|9|@]|A|$]]|$1|W|3|X|5|T|7|3J|8|@$D|3K|E|3L|F|G]|$D|3M|E|3N|F|G]|$D|3O|E|3P|F|G]|$D|3Q|E|3R|F|G]|$D|3S|E|3T|F|G]|$D|3U|E|3V|F|G]|$D|3W|E|3X|F|G]]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|3Y|8|@]|9|@]|A|$]]|$1|Z|3|10|5|6|7|3Z|8|@$D|40|E|41|F|G]|$D|42|E|43|F|G]]|9|@]|A|$]]|$1|11|3|12|5|6|7|44|8|@$D|45|E|46|F|G]]|9|@]|A|$]]|$1|13|3|14|5|L|7|47|8|@]|9|@]|A|$M|N]]|$1|15|3|-4|5|6|7|48|8|@]|9|@]|A|$]]|$1|16|3|17|5|6|7|49|8|@]|9|@]|A|$]]|$1|18|3|19|5|6|7|4A|8|@]|9|@]|A|$]]|$1|1A|3|1B|5|L|7|4B|8|@]|9|@]|A|$M|N]]|$1|1C|3|1D|5|6|7|4C|8|@]|9|@]|A|$]]|$1|1E|3|1F|5|L|7|4D|8|@]|9|@]|A|$M|N]]|$1|1G|3|1H|5|6|7|4E|8|@$D|4F|E|4G|F|G]|$D|4H|E|4I|F|G]]|9|@]|A|$]]|$1|1I|3|1J|5|L|7|4J|8|@]|9|@]|A|$M|N]]|$1|1K|3|1L|5|6|7|4K|8|@]|9|@]|A|$]]|$1|1M|3|1N|5|L|7|4L|8|@]|9|@]|A|$M|N]]|$1|1O|3|1P|5|6|7|4M|8|@]|9|@]|A|$]]|$1|1Q|3|1R|5|L|7|4N|8|@]|9|@]|A|$M|N]]|$1|1S|3|1T|5|6|7|4O|8|@$D|4P|E|4Q|F|G]|$D|4R|E|4S|F|G]]|9|@]|A|$]]|$1|1U|3|-4|5|6|7|4T|8|@]|9|@]|A|$]]|$1|1V|3|1W|5|6|7|4U|8|@]|9|@]|A|$]]|$1|1X|3|1Y|5|6|7|4V|8|@$D|4W|E|4X|F|G]|$D|4Y|E|4Z|F|G]|$D|50|E|51|F|G]]|9|@]|A|$]]|$1|1Z|3|20|5|L|7|52|8|@]|9|@]|A|$M|N]]|$1|21|3|22|5|6|7|53|8|@$D|54|E|55|F|G]]|9|@]|A|$]]|$1|23|3|24|5|L|7|56|8|@]|9|@]|A|$M|N]]|$1|25|3|26|5|6|7|57|8|@]|9|@]|A|$]]|$1|27|3|28|5|6|7|58|8|@$D|59|E|5A|F|G]|$D|5B|E|5C|F|G]]|9|@]|A|$]]|$1|29|3|-4|5|6|7|5D|8|@]|9|@]|A|$]]|$1|2A|3|2B|5|6|7|5E|8|@]|9|@]|A|$]]|$1|2C|3|2D|5|6|7|5F|8|@$D|5G|E|5H|F|G]]|9|@]|A|$]]|$1|2E|3|2F|5|L|7|5I|8|@]|9|@]|A|$M|N]]|$1|2G|3|2H|5|6|7|5J|8|@$D|5K|E|5L|F|G]]|9|@]|A|$]]|$1|2I|3|2J|5|L|7|5M|8|@]|9|@]|A|$M|N]]|$1|2K|3|2L|5|6|7|5N|8|@$D|5O|E|5P|F|G]|$D|5Q|E|5R|F|G]|$D|5S|E|5T|F|G]|$D|5U|E|5V|F|G]|$D|5W|E|5X|F|G]]|9|@]|A|$]]|$1|2M|3|-4|5|6|7|5Y|8|@]|9|@]|A|$]]|$1|2N|3|2O|5|6|7|5Z|8|@]|9|@]|A|$]]|$1|2P|3|-4|5|6|7|60|8|@]|9|@]|A|$]]|$1|2Q|3|2R|5|T|7|61|8|@]|9|@$D|62|E|63|1|64]]|A|$]]|$1|2S|3|2T|5|T|7|65|8|@]|9|@$D|66|E|67|1|68]]|A|$]]|$1|2U|3|-4|5|6|7|69|8|@]|9|@]|A|$]]|$1|2V|3|-4|5|6|7|6A|8|@]|9|@]|A|$]]]|2W|$2X|$5|2Y|2Z|30|A|$31|32]]|33|$5|2Y|2Z|30|A|$31|34]]]]

<h3>Process GET parameters</h3>
The <a href="https://docs.oracle.com/javaee/7/javaserver-faces-2-2/vdldocs-facelets/f/viewParam.html" rel="noreferrer"><code>&lt;f:viewParam&gt;</code></a> manages the setting, conversion and validation of GET parameters. It's like the <code>&lt;h:inputText&gt;</code>, but then for GET parameters.
The following example
<pre><code>&lt;f:metadata&gt;
 &lt;f:viewParam name=&quot;id&quot; value=&quot;#{bean.id}&quot; /&gt;
&lt;/f:metadata&gt;
</code></pre>
does basically the following:
<ul>
<li>Get the request parameter value by name <code>id</code>.</li>
<li>Convert and validate it if necessary (you can use <code>required</code>, <code>validator</code> and <code>converter</code> attributes and nest a <code>&lt;f:converter&gt;</code> and <code>&lt;f:validator&gt;</code> in it like as with <code>&lt;h:inputText&gt;</code>)</li>
<li>If conversion and validation succeeds, then set it as a bean property represented by <code>#{bean.id}</code> value, or if the <code>value</code> attribute is absent, then set it as request attribtue on name <code>id</code> so that it's available by <code>#{id}</code> in the view.</li>
</ul>
So when you open the page as <code>foo.xhtml?id=10</code> then the parameter value <code>10</code> get set in the bean this way, right before the view is rendered.
As to validation, the following example sets the param to <code>required=&quot;true&quot;</code> and allows only values between 10 and 20. Any validation failure will result in a message being displayed.
<pre><code>&lt;f:metadata&gt;
 &lt;f:viewParam id=&quot;id&quot; name=&quot;id&quot; value=&quot;#{bean.id}&quot; required=&quot;true&quot;&gt;
 &lt;f:validateLongRange minimum=&quot;10&quot; maximum=&quot;20&quot; /&gt;
 &lt;/f:viewParam&gt;
&lt;/f:metadata&gt;
&lt;h:message for=&quot;id&quot; /&gt;
</code></pre>
<hr />
<h3>Performing business action on GET parameters</h3>
You can use the <a href="https://docs.oracle.com/javaee/7/javaserver-faces-2-2/vdldocs-facelets/f/viewAction.html" rel="noreferrer"><code>&lt;f:viewAction&gt;</code></a> for this.
<pre><code>&lt;f:metadata&gt;
 &lt;f:viewParam id=&quot;id&quot; name=&quot;id&quot; value=&quot;#{bean.id}&quot; required=&quot;true&quot;&gt;
 &lt;f:validateLongRange minimum=&quot;10&quot; maximum=&quot;20&quot; /&gt;
 &lt;/f:viewParam&gt;
 &lt;f:viewAction action=&quot;#{bean.onload}&quot; /&gt;
&lt;/f:metadata&gt;
&lt;h:message for=&quot;id&quot; /&gt;
</code></pre>
with
<pre><code>public void onload() {
 // ...
}
</code></pre>
The <code>&lt;f:viewAction&gt;</code> is however new since JSF 2.2 (the <code>&lt;f:viewParam&gt;</code> already exists since JSF 2.0). If you can't upgrade, then your best bet is using <a href="https://docs.oracle.com/javaee/7/javaserver-faces-2-2/vdldocs-facelets/f/event.html" rel="noreferrer"><code>&lt;f:event&gt;</code></a> instead.
<pre><code>&lt;f:event type=&quot;preRenderView&quot; listener=&quot;#{bean.onload}&quot; /&gt;
</code></pre>
This is however invoked on every request. You need to explicitly check if the request isn't a postback:
<pre><code>public void onload() {
 if (!FacesContext.getCurrentInstance().isPostback()) {
 // ...
 }
}
</code></pre>
When you would like to skip &quot;Conversion/Validation failed&quot; cases as well, then do as follows:
<pre><code>public void onload() {
 FacesContext facesContext = FacesContext.getCurrentInstance();
 if (!facesContext.isPostback() &amp;&amp; !facesContext.isValidationFailed()) {
 // ...
 }
}
</code></pre>
Using <code>&lt;f:event&gt;</code> this way is in essence a workaround/hack, that's exactly why the <code>&lt;f:viewAction&gt;</code> was introduced in JSF 2.2.
<hr />
<h3>Pass view parameters to next view</h3>
You can &quot;pass-through&quot; the view parameters in navigation links by setting <code>includeViewParams</code> attribute to <code>true</code> or by adding <code>includeViewParams=true</code> request parameter.
<pre><code>&lt;h:link outcome=&quot;next&quot; includeViewParams=&quot;true&quot;&gt;
&lt;!-- Or --&gt;
&lt;h:link outcome=&quot;next?includeViewParams=true&quot;&gt;
</code></pre>
which generates with the above <code>&lt;f:metadata&gt;</code> example basically the following link
<pre><code>&lt;a href=&quot;next.xhtml?id=10&quot;&gt;
</code></pre>
with the original parameter value.
This approach only requires that <code>next.xhtml</code> has also a <code>&lt;f:viewParam&gt;</code> on the very same parameter, otherwise it won't be passed through.
<hr />
<h3>Use GET forms in JSF</h3>
The <code>&lt;f:viewParam&gt;</code> can also be used in combination with &quot;plain HTML&quot; GET forms.
<pre><code>&lt;f:metadata&gt;
 &lt;f:viewParam id=&quot;query&quot; name=&quot;query&quot; value=&quot;#{bean.query}&quot; /&gt;
 &lt;f:viewAction action=&quot;#{bean.search}&quot; /&gt;
&lt;/f:metadata&gt;
...
&lt;form&gt;
 &lt;label for=&quot;query&quot;&gt;Query&lt;/label&gt;
 &lt;input type=&quot;text&quot; name=&quot;query&quot; value=&quot;#{empty bean.query ? param.query : bean.query}&quot; /&gt;
 &lt;input type=&quot;submit&quot; value=&quot;Search&quot; /&gt;
 &lt;h:message for=&quot;query&quot; /&gt;
&lt;/form&gt;
...
&lt;h:dataTable value=&quot;#{bean.results}&quot; var=&quot;result&quot; rendered=&quot;#{not empty bean.results}&quot;&gt;
 ...
&lt;/h:dataTable&gt;
</code></pre>
With basically this <code>@RequestScoped</code> bean:
<pre><code>private String query;
private List&lt;Result&gt; results;

public void search() {
 results = service.search(query);
}
</code></pre>
Note that the <code>&lt;h:message&gt;</code> is for the <code>&lt;f:viewParam&gt;</code>, not the plain HTML <code>&lt;input type=&quot;text&quot;&gt;</code>! Also note that the input value displays <code>#{param.query}</code> when <code>#{bean.query}</code> is empty, because the submitted value would otherwise not show up at all when there's a validation or conversion error. Please note that this construct is invalid for JSF input components (it is doing that &quot;under the covers&quot; already).
<hr />
<h3>See also:</h3>
<ul>
<li><a href="https://stackoverflow.com/questions/4888942/viewparam-vs-managedpropertyvalue-param-id">ViewParam vs @ManagedProperty(value = &quot;#{param.id}&quot;)</a></li>
<li><a href="http://balusc.blogspot.com/2011/09/communication-in-jsf-20.html#ProcessingGETRequestParameters" rel="noreferrer">Communication in JSF 2.0 - Processing GET request parameters</a></li>
</ul>

blocks|key|267755|text|使用viewParam和includeViewParams=true将参数从视图发送到其他视图，从发送者视图发送到接收者视图|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|267756|发件人中的|267757|267758|声明要发送的参数。我们可以发送String，Object，…|ordered-list-item|267759|267760|Sender.xhtml|267761|<f:metadata>
++++++<f:viewParam+name="ID"+value="#{senderMB._strID}"+/>
</f:metadata>|code-block|syntax|javascript|267762|单击按钮我们将发送参数ID，它将包含在带有senderMB._arrData返回字符串|267763|+event的“includeViewParams=true”中单击按钮触发senderMB.clickBtnDetail(+dto+)|CODE|267764|267765|267766|<p:dataTable+rowIndexVar="index"+id="dataTale"value="#{senderMB._arrData}"+var="dto">
++++++<p:commandButton+action="#{senderMB.clickBtnDetail(dto)}"+value="見る"+
++++++ajax="false"/>
</p:dataTable>|267767|在senderMB.clickBtnDetail(dto)中，我们使用从按钮事件(dto)中获得的参数来赋值_strID，这里是Sender_DTO并赋值给senderMB._strID|267768|Sender_MB.java
++++public+String+clickBtnDetail(sender_DTO+sender_dto)+{
++++++++this._strID+=+sender_dto.getStrID();
++++++++return+"Receiver?faces-redirect=true&includeViewParams=true";
++++}|267769|单击该链接时，该链接将变为http://localhost:8080/my_project/view/Receiver.xhtml?*ID=12345*|267770|接收器中的|267771|267772|Get+viewParam+Receiver.xhtml+In+Receiver我们声明f:viewParam要从get+request+(receive)中获取参数，接收方的参数名称必须与|267773|(ViewParam)|267774|相同|267775|Receiver.xhtml|267776|<f:metadata><f:viewParam+name="ID"+value="#{receiver_MB._strID}"/></f:metadata>|267777|它将从发送者视图中获取参数ID并分配给receiver_MB._strID|267778|267779|在接收器中使用viewParam，我们希望在页面渲染之前在sql查询中使用这个参数，这样我们就可以使用preRenderView事件。我们将不使用构造函数，因为构造函数将在接收到viewParam之前被调用，因此我们添加了|267780|267781|267782|<f:event+listener="#{receiver_MB.preRenderView}"+type="preRenderView"+/>|267783|into+f:metadata标签|267784|267785|<f:metadata>
<f:viewParam+name="ID"+value="#{receiver_MB._strID}"+/>
<f:event+listener="#{receiver_MB.preRenderView}"
++++++++++++type="preRenderView"+/>
</f:metadata>|267786|现在我们想在我们的read数据库方法中使用这个参数，它可以使用|267787|Receiver_MB.java
public+void+preRenderView(ComponentSystemEvent+event)+throws+Exception+{
++++++++if+(FacesContext.getCurrentInstance().isPostback())+{
++++++++++++return;
++++++++}
++++++++readFromDatabase();
++++}
private+void+readFromDatabase()+{
//use+_strID+to+read+and+set+property+++
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Send params from View to an other View, from Sender View to Receiver View use viewParam and includeViewParams=true
In Sender
<ol>
<li>Declare params to be sent. We can send String, Object,…</li>
</ol>
Sender.xhtml
<pre><code>&lt;f:metadata&gt;
 &lt;f:viewParam name=&quot;ID&quot; value=&quot;#{senderMB._strID}&quot; /&gt;
&lt;/f:metadata&gt;
</code></pre>
<ol start="2">
<li>We’re going send param ID, it will be included with <code>“includeViewParams=true”</code> in return String of click button event
Click button fire senderMB.clickBtnDetail(dto) with dto from senderMB._arrData</li>
</ol>
Sender.xhtml
<pre><code>&lt;p:dataTable rowIndexVar=&quot;index&quot; id=&quot;dataTale&quot;value=&quot;#{senderMB._arrData}&quot; var=&quot;dto&quot;&gt;
 &lt;p:commandButton action=&quot;#{senderMB.clickBtnDetail(dto)}&quot; value=&quot;見る&quot; 
 ajax=&quot;false&quot;/&gt;
&lt;/p:dataTable&gt;
</code></pre>
In senderMB.clickBtnDetail(dto) we assign _strID with argument we got from button event (dto), here this is Sender_DTO and assign to senderMB._strID
<pre><code>Sender_MB.java
 public String clickBtnDetail(sender_DTO sender_dto) {
 this._strID = sender_dto.getStrID();
 return &quot;Receiver?faces-redirect=true&amp;includeViewParams=true&quot;;
 }
</code></pre>
The link when clicked will become <code>http://localhost:8080/my_project/view/Receiver.xhtml?*ID=12345*</code>
In Recever
<ol>
<li>Get viewParam
Receiver.xhtml
In Receiver we declare f:viewParam to get param from get request (receive), the name of param of receiver must be the same with sender (page)</li>
</ol>
Receiver.xhtml
<pre><code>&lt;f:metadata&gt;&lt;f:viewParam name=&quot;ID&quot; value=&quot;#{receiver_MB._strID}&quot;/&gt;&lt;/f:metadata&gt;
</code></pre>
It will get param ID from sender View and assign to receiver_MB._strID
<ol start="2">
<li>Use viewParam
In Receiver, we want to use this param in sql query before the page render, so that we use preRenderView event. We are not going to use constructor because constructor will be invoked before viewParam is received
So that we add</li>
</ol>
Receiver.xhtml
<pre><code>&lt;f:event listener=&quot;#{receiver_MB.preRenderView}&quot; type=&quot;preRenderView&quot; /&gt;
</code></pre>
into f:metadata tag
Receiver.xhtml
<pre><code>&lt;f:metadata&gt;
&lt;f:viewParam name=&quot;ID&quot; value=&quot;#{receiver_MB._strID}&quot; /&gt;
&lt;f:event listener=&quot;#{receiver_MB.preRenderView}&quot;
 type=&quot;preRenderView&quot; /&gt;
&lt;/f:metadata&gt;
</code></pre>
Now we want to use this param in our read database method, it is available to use
<pre><code>Receiver_MB.java
public void preRenderView(ComponentSystemEvent event) throws Exception {
 if (FacesContext.getCurrentInstance().isPostback()) {
 return;
 }
 readFromDatabase();
 }
private void readFromDatabase() {
//use _strID to read and set property 
}
</code></pre>

Can anyone clarify how we can use in general, or a in real world example, this snippet?

<pre><code>&lt;f:metadata&gt;
 &lt;f:viewParam id="id" value="#{bean.id}" /&gt;
 &lt;f:viewAction action="#{bean.init}" /&gt;
&lt;/f:metadata&gt;
</code></pre>

What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?

数据库

有没有人能说明一下，我们如何在一般情况下，或者在现实世界中使用这个片段？<f:metadata> <f:viewParam id="id" value="#{bean.id}" /> <f:viewAction action="#{bean.init}" /></f:metadata>

问<f:metadata>、<f:viewParam>和<f:viewAction>有什么用途？
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问<f:metadata>、<f:viewParam>和<f:viewAction>有什么用途？
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