blocks|key|3529|text|最简单的方法是手动枚举枚举，将其转储到一个集合中，然后返回该集合的枚举。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3530|如果做不到这一点，您可以组合Google+Guava操作来完成此操作，如下所示：|offset|length|3531|//+the+map+of+enumerations
Map<?,+Enumeration<String>>+map+=+...

//+a+function+that+turns+enumerations+into+iterators
Function<Enumeration<String>,+Iterator<String>>+eumerationToIteratorFunction+=+new+Function<Enumeration<String>,+Iterator<String>>()+{
+++public+Iterator<String>+apply(Enumeration<String>+enumeration)+{
++++++return+Iterators.forEnumeration(enumeration);
+++}
};

//+transform+the+enumerations+into+iterators,+using+the+function
Collection<Iterator<String>>+iterators+=+Collections2.transform(map.values(),+eumerationToIteratorFunction);

//+combine+the+iterators
Iterator<String>+combinedIterator+=+Iterators.concat(iterators);

//+convert+the+combined+iterator+back+into+an+enumeration
Enumeration<String>+combinedEnumeration+=+Iterators.asEnumeration(combinedIterator);+|code-block|syntax|javascript|3532|它相当繁琐，但Enumeration很旧，在现代API中的支持也相当差。通过明智地使用静态导入，可以将其精简一点。您甚至可以在一条函数风格的语句中完成所有操作：|style|CODE|3533|Map<?,+Enumeration<String>>+map+=+...

Enumeration<String>+combinedEnumeration+=+asEnumeration(concat(
+++transform(map.values(),+new+Function<Enumeration<String>,+Iterator<String>>()+{
++++++public+Iterator<String>+apply(Enumeration<String>+enumeration)+{
+++++++++return+forEnumeration(enumeration);
++++++}
+++})
));+|3534|这种方法的好处是高效-它做任何事情都很懒惰，而且直到你要求它才会迭代。不过，在你的情况下，效率可能并不重要，在这种情况下，只需以简单的方式进行即可。|3535|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/guava-libraries/^0|0|E|C|0|0|0|7|B|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@$D|12|E|13|1|14]]|A|$]]|$1|F|3|G|5|H|7|15|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|16|8|@$D|17|E|18|M|N]]|9|@]|A|$]]|$1|O|3|P|5|H|7|19|8|@]|9|@]|A|$I|J]]|$1|Q|3|R|5|6|7|1A|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

The simplest approach is just to manually enumerate over the enumerations, dump them into a collection, then return an enumeration of that collection. 

Failing that, you could combine <a href="http://code.google.com/p/guava-libraries/" rel="nofollow">Google Guava</a> operations to do this, something like this:

<pre><code>// the map of enumerations
Map&lt;?, Enumeration&lt;String&gt;&gt; map = ...

// a function that turns enumerations into iterators
Function&lt;Enumeration&lt;String&gt;, Iterator&lt;String&gt;&gt; eumerationToIteratorFunction = new Function&lt;Enumeration&lt;String&gt;, Iterator&lt;String&gt;&gt;() {
 public Iterator&lt;String&gt; apply(Enumeration&lt;String&gt; enumeration) {
 return Iterators.forEnumeration(enumeration);
 }
};

// transform the enumerations into iterators, using the function
Collection&lt;Iterator&lt;String&gt;&gt; iterators = Collections2.transform(map.values(), eumerationToIteratorFunction);

// combine the iterators
Iterator&lt;String&gt; combinedIterator = Iterators.concat(iterators);

// convert the combined iterator back into an enumeration
Enumeration&lt;String&gt; combinedEnumeration = Iterators.asEnumeration(combinedIterator); 
</code></pre>

It's pretty cumbersome, but <code>Enumeration</code> is old and rather poorly supported in modern APIs. It can be slimmed down a bit by judicious use of static imports. You can even do the whole thing in a single function-style statement:

<pre><code>Map&lt;?, Enumeration&lt;String&gt;&gt; map = ...

Enumeration&lt;String&gt; combinedEnumeration = asEnumeration(concat(
 transform(map.values(), new Function&lt;Enumeration&lt;String&gt;, Iterator&lt;String&gt;&gt;() {
 public Iterator&lt;String&gt; apply(Enumeration&lt;String&gt; enumeration) {
 return forEnumeration(enumeration);
 }
 })
)); 
</code></pre>

This approach has the benefit of being efficient - it does everything lazily, and won't iterate until you ask it to. Efficiency may not matter in your case, though, in which case just do it the simple way.

blocks|key|5197299|text|您可以创建自己的具有addAll+(Enumeration<E>+enumeration)方法的自定义Enumeration实现。然后在所有底层ResourceBundle对象上调用getKeys()，并将它们全部添加到您自己的Enumeration的新实例中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5197300|entityMap^0|A|Z|1F|B|20|E|2J|9|36|B|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|G|$]]

You can create your own custom <code>Enumeration</code> implementation that will have a <code>addAll (Enumeration&lt;E&gt; enumeration)</code> method. Then call <code>getKeys()</code> on all underlying <code>ResourceBundle</code> objects, and add them all to a new instance of your own <code>Enumeration</code>.

blocks|key|3613|text|您可以使用Guava's+Iterators类:使用forEnumeration转换每个枚举，然后concat迭代器，并使用asEnumeration将生成的迭代器转换回枚举。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3614|或者使用类似于Guava的concat方法的代码自己实现一个连接枚举。|3615|entityMap|0|LINK|mutability|MUTABLE|url|http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/collect/Iterators.html^0|Q|E|1D|6|1Q|D|5|H|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

You could use <a href="http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/collect/Iterators.html" rel="nofollow">Guava's Iterators</a> class: transform each Enumeration using <code>forEnumeration</code>, then <code>concat</code> the iterators, and transform the resulting iterator back to an Enumeration using <code>asEnumeration</code>.

Or implement an concatenating Enumeration yourself using code similar to Guava's concat method.

blocks|key|1023538|text|这就是我们最终想出的方案。它有更多的代码，但我认为分享基础知识是公平的。这个解决方案遵循了skaffman的建议。感谢所有的贡献。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1023539|public+class+ChainedResourceBundle+extends+ResourceBundle+implements+Enumeration<String>+{

++++Iterator<Map.Entry<Module,+ResourceBundle>>+tables;
++++private+Enumeration<String>+++++++++++++++++keys;

++++private+Map<Module,+ResourceBundle>+++++++++internalMap++++=+new+HashMap<Module,+ResourceBundle>();
++++private+Map<String,+String>+++++++++++++++++customizedKeys+=+new+HashMap<String,+String>();


++++@Override
++++public+Enumeration<String>+getKeys()+{
++++++++tables+=+internalMap.entrySet().iterator();
++++++++nextTable();
++++++++return+this;
++++}


++++@Override
++++public+boolean+hasMoreElements()+{
++++++++return+keys+!=+null;
++++}


++++@Override
++++public+String+nextElement()+{
++++++++String+key+=+keys.nextElement();
++++++++if+(!keys.hasMoreElements())+{
++++++++++++nextTable();
++++++++}
++++++++return+key;
++++}

++++private+void+nextTable()+{
++++++++if+(tables.hasNext())+{
++++++++++++keys+=+tables.next().getValue().getKeys();
++++++++}+else+{
++++++++++++keys+=+null;
++++++++}
++++}

}|code-block|syntax|javascript|1023540|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This is what we finally came up with. There is more code to it but thought it would be fair to share the basics. The solution follows a bit skaffman's proposal.
Thanks to all contributions.

<pre><code>public class ChainedResourceBundle extends ResourceBundle implements Enumeration&lt;String&gt; {

 Iterator&lt;Map.Entry&lt;Module, ResourceBundle&gt;&gt; tables;
 private Enumeration&lt;String&gt; keys;

 private Map&lt;Module, ResourceBundle&gt; internalMap = new HashMap&lt;Module, ResourceBundle&gt;();
 private Map&lt;String, String&gt; customizedKeys = new HashMap&lt;String, String&gt;();


 @Override
 public Enumeration&lt;String&gt; getKeys() {
 tables = internalMap.entrySet().iterator();
 nextTable();
 return this;
 }


 @Override
 public boolean hasMoreElements() {
 return keys != null;
 }


 @Override
 public String nextElement() {
 String key = keys.nextElement();
 if (!keys.hasMoreElements()) {
 nextTable();
 }
 return key;
 }

 private void nextTable() {
 if (tables.hasNext()) {
 keys = tables.next().getValue().getKeys();
 } else {
 keys = null;
 }
 }

}
</code></pre>

blocks|key|1023547|text|您可以使用sun.misc.CompoundEnumeration。它是Java的一部分，不需要额外的库。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1023548|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You can use sun.misc.CompoundEnumeration. It is part of Java without the need of additional libraries.

blocks|key|3630|text|您还可以像这样使用Vector|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3631|public+Enumeration<String>+getKeys()+{
++++ResourceBundle+parent+=+this.parent;
++++Set<String>+keySet+=+this.handleKeySet();
++++List<String>+parentKeySet+=+(parent+!=+null)+?+list(parent.getKeys())+:+null;
++++keySet.addAll(parentKeySet);
++++return+new+Vector<>(keySet).elements();
}|code-block|syntax|javascript|3632|entityMap^0|9|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You can also use <code>Vector</code> like 

<pre><code>public Enumeration&lt;String&gt; getKeys() {
 ResourceBundle parent = this.parent;
 Set&lt;String&gt; keySet = this.handleKeySet();
 List&lt;String&gt; parentKeySet = (parent != null) ? list(parent.getKeys()) : null;
 keySet.addAll(parentKeySet);
 return new Vector&lt;&gt;(keySet).elements();
}
</code></pre>

I had to subclass <code>ResourceBundle</code> due to our specific needs.

However, to override <code>getKeys()</code>, I am a bit in trouble. This <code>getKeys</code> needs to somehow concatenate from a map of underlying <code>ResourceBundle</code>s. How can I do that?

Thanks

EDIT: While submitting I came across an idea. Basically we have for each of our <code>Module</code> a <code>ResourceBundle</code>, so my code looks like this so far:

<pre><code>public Enumeration&lt;String&gt; getKeys() {
 ArrayList&lt;String&gt; keys = new ArrayList&lt;String&gt;();

 for (Map.Entry&lt;Module, ResourceBundle&gt; entry : internalMap.entrySet()) {
 Enumeration&lt;String&gt; tmp = entry.getValue().getKeys();
 while (tmp.hasMoreElements()) {
 String key = tmp.nextElement();
 keys.add(key);
 }
 }

 return Collections.enumeration(keys);
 }
</code></pre>

concatenate several enumerations?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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由于我们的特定需求，我不得不将ResourceBundle子类化。然而，为了覆盖getKeys()，我遇到了一点麻烦。这个getKeys需要以某种方式从底层ResourceBundle的映射连接起来。我该怎么做呢？谢谢编辑:在提交的时候，我想到了一个想法。基本上，我们每个Module都有一个ResourceBundle...

问连接多个枚举？
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问连接多个枚举？EN