如何只将值传递给java方法一次？

Question

Let's say i have a java method:

private String (StringUtility stringUtil)
{
   String maxValue = stringUtil.getMaxValue()
}

Now, the StringUtility holds the maxValue and read it from configuration field loaded by Spring and won't be changed during run time . this method is going to be called every 1ms. So, if the maxVlue won't be changed once it was loaded, is there another way to pass it to the method instead to get it every time we call the method and avoid a load when calling the stringUtil every time just to get the maxValue?

Thank you.

Answer 1

This sounds like a good fit for a singleton you load at the start of your app and then reuse the values.

Something like that:

public final class StringUtility {
    private static String maxValue;
    public static final synchronized String getMaxValue(){
        if(maxValue == null){
            //set value
        }
        return maxValue;
    }
}

Then use it in your method.

Answer 2

Since you're using Spring, why not make StringUtility cache values? You can accomplish this using Spring Cache annotations .

Depending on how your bean is described, you can do this:

@Component
public class StringUtility {

    @Value("${maxValue}")
    private String maxValue;

    @Cacheable("string-utility")
    public String getMaxValue() {
        return maxValue;
    }
}

I'll leave the configuration and full wiring as an exercise for the reader.

(Even if you don't go the route of caching with Spring, this is the perfect use case for caches anyway. Since you're guaranteed that this value will never be evicted from the cache, you can rely on it to provide the value instead. Alternatively, this could be interpreted as a premature optimization, since the call would be cheap regardless of what you do.)