逛spring源码所发现的有趣的写法。

今日逛spring源码发现在DefaultListableBeanFactory类发现有两个方法写的挺有趣，利用函数式接口，让方法的执行逻辑交给方法调用者来决定，提高了代码的灵活性。特此记录，代码如下：

	private void removeManualSingletonName(String beanName) {
		updateManualSingletonNames(set -> set.remove(beanName), set -> set.contains(beanName));
	}

	
	private void updateManualSingletonNames(Consumer> action, Predicate> condition) {
		if (hasBeanCreationStarted()) {
			// Cannot modify startup-time collection elements anymore (for stable iteration)
			synchronized (this.beanDefinitionMap) {
				if (condition.test(this.manualSingletonNames)) {
					Set updatedSingletons = new linkedHashSet<>(this.manualSingletonNames);
					action.accept(updatedSingletons);
					this.manualSingletonNames = updatedSingletons;
				}
			}
		}
		else {
			// Still in startup registration phase
			if (condition.test(this.manualSingletonNames)) {
				action.accept(this.manualSingletonNames);
			}
		}
	}

以下是自己模拟的代码：

package lambda.test;

import java.util.HashSet;
import java.util.linkedHashSet;
import java.util.Set;
import java.util.function.Consumer;
import java.util.function.Predicate;


public class MethodLambdaTest {

    private static Set set = new HashSet();


    static{
        set.add("1");
        set.add("2");
    }


    public static void main(String[] args) {
        MethodLambdaTest methodLambdaTest = new MethodLambdaTest();
        methodLambdaTest.doSome(System.out::println, b -> b.contains("1"));
    }

    public void doSome(Consumer> action, Predicate> condition) {
        Set updatedSingletons = new linkedHashSet<>(set);
        if (condition.test(updatedSingletons)) {
            action.accept(updatedSingletons);
        }
    }
}

输出：

非常好用