java.util.Properties 中的多个值
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Multiple values in java.util.Properties
提问by ClueMinus
It seems that java.util.Properties assumes one value per propery key. That is,
似乎 java.util.Properties 假定每个属性键一个值。那是，
foo=1
foo=2
is not expected,
不是预期的，
Is there a class for this kind of multi-value property sheet, which also provides the load method?
这种多值属性表有没有类，还提供了load方法？
采纳答案by Nick Holt
Try:
尝试：
foo=1,2
String[] foos = properties.getProperty("foo").split(",");
回答by ZZ Coder
The java.util.Properties function is pretty limited. If you want support list, you might want try PropertyConfiguration from Apache Commons Configuration,
java.util.Properties 函数非常有限。如果您需要支持列表，您可能需要尝试来自 Apache Commons Configuration 的 PropertyConfiguration，
With it, you can set any delimiters to your list and it will split for you automatically. You can also do other fancy things in properties file. For example,
有了它，您可以为您的列表设置任何分隔符，它会自动为您拆分。您还可以在属性文件中做其他花哨的事情。例如，
foo=item1, item2
bar=${foo}, item3
number=123
You can retrieve it like this,
你可以像这样检索它，
Configuration config = new PropertiesConfiguration("your.properties");
String[] items = config.getStringArray("bar"); // return {"item1", "item2", "item3"}
int number = config.getInt("number", 456); // 456 is default value
回答by KLE
Correct answer by Nick.
尼克的正确答案。
Or, if you can give a different subname to each value, you could have your properties be:
或者，如果您可以为每个值指定不同的子名称，您的属性可以是：
my.properties
foo.title=Foo
foo.description=This a big fat foo.
回答by Pablojim
This won't provide the load method but a place to store them you could use a apache commons multivaluemap:
这不会提供加载方法，而是提供一个存储它们的地方，您可以使用 apache commons 多值映射：
"A MultiValueMap decorates another map, allowing it to have more than one value for a key. "
“MultiValueMap 装饰另一张地图，允许它为一个键拥有多个值。”
This is often a requirement for http request parameters...
这通常是对http请求参数的要求...
http://commons.apache.org/collections/apidocs/org/apache/commons/collections/map/MultiValueMap.html
http://commons.apache.org/collections/apidocs/org/apache/commons/collections/map/MultiValueMap.html
回答by Clerenz
If you have a more complex example you might use the following:
如果您有更复杂的示例，您可以使用以下内容：
# pairs of properties
source1=foo
target1=bar
source2=anotherFoo
target2=regardingBar
source3= ...
In your code you will have to search:
在您的代码中，您必须搜索：
Map<String, String> myMap = new HashMap<>();
for (int i=1; i<max; i++) {
String source = properties.get("source" + i);
String target = properties.get("target" + i);
if (source == null || target == null) {
break;
}
myMap.put(source, target);
}
Drawback: updating the properties file. If you remove values *2, all the following values will not be added. To improve you might want to replace the break with a continue and stick to a maximum of allowed pairs.
缺点：更新属性文件。如果删除值 *2，则不会添加以下所有值。为了改进，您可能需要用继续替换中断并坚持最多允许的对。
