Java service provider-lookup mechanism(发现机制)-1

 

public interface CacheLookup {

    public String naming();

    public Object get();

    public void add(Object cache);

    public void remove(Object cache);
}

 

public class DefaultCacheLookup implements CacheLookup {

    private List<Object> cached;

    private Object defaultCache;

    public DefaultCacheLookup() {
        cached = new ArrayList<Object>();
    }

    public String naming() {
        return "default cache lookup provider";
    }

    @Override
public Object get() {
        int size = cached.size();
        if (size < 1) {
            return defaultCache;
        }
        Random random = new Random(System.currentTimeMillis());
        return cached.get(random.nextInt(size));
    }

    @Override
public void add(Object cache) {
        cached.add(cache);
    }

    @Override
public void remove(Object cache) {
        cached.remove(cache);
    }
}

 

public class AdvancedCacheLookup implements CacheLookup {

    private List<Object> cached;

    private Object defaultCache;

    public AdvancedCacheLookup() {
        cached = new ArrayList<Object>();
    }

    public String naming() {
        return "advanced cache lookup provider";
    }

    @Override
public Object get() {
        int size = cached.size();
        if (size < 1) {
            return defaultCache;
        }
        Random random = new Random(System.currentTimeMillis());
        return cached.get(random.nextInt(size));
    }

    @Override
public void add(Object cache) {
        cached.add(cache);
    }

    @Override
public void remove(Object cache) {
        cached.remove(cache);
    }
}

 

    classpath下META-INF\services\com.xxx.ddal.CacheLookup:

 

com.xxx.ddal.DefaultCacheLookup
com.xxx.ddal.AdvancedCacheLookup

 

@Test
public void test() {
    Iterator<CacheLookup> interator = Service.providers(CacheLookup.class);
    while (interator.hasNext()) {
        CacheLookup lookup = interator.next();
        System.out.println(lookup.getClass());
        System.out.println(lookup.naming());
    }
}

 

 

class com.xxx.ddal.DefaultCacheLookup

default cache lookup provider

class com.xxx.ddal.AdvancedCacheLookup

advanced cache lookup provider