java属性文件中是否可以将一个变量指向另一个变量？

Question

I have a lot of rows/entry in my properties file. Rows are grouped in categories to keep file easier to maintain. I have two key which have the same value. I don't want to remove one because it makes my file harder to maintain.

#category1
var1=foo
....
#category2
var2=foo

Is there any way to make var1 points to var2? I think about sth like that:

    #category1
    var1=->var2 #point to var2
    ....
    #category2
    var2=foo

Answer 1

java.util.Properties implements the Map interface so you can do everything that this interface offers with it. To allow value to represent a reference to an other key you could wrap the code for getting the value in such a ways that it check whether the value is actually key and then return the value that is mapped by that key.

so you could implement something like this:

String value1 = p.getProperty("var1");
while(p.containsKey(value1)) {
    value1 = p.getProperty(value1);
}

better: add a prefix - $ for example - to value to identify a reference, only if present then resolve:

String value1 = p.getProperty("var1");
while(value1.startsWith("$")) {
    value1 = p.getProperty(value1.substring(1));
}

A good way for wrapping the retrieve-code is by extending the Properties class and override the method getProperty .

For org.springframework.context.support.ReloadableResourceBundleMessageSource you could extend it, override which ever methods you want and configure spring to inject your version of the class.