ServiceManager

ServiceManager

import java.util.HashMap;
import java.util.Map;

/**
 * 服务管理器<hr/>
 * 1. 模块之间是相互独立的并列关系, 不能相互调用<br/>
 * 2. 需要调用时, 通过下沉{@link Service}的方式<br/>
 * <p>
 *
 * @author puke
 * @version 2021/6/24
 */
@SuppressWarnings("unchecked")
public class ServiceManager {

    private static final Map<Class<? extends Service>, Class<? extends Service>> IMPL_MAPPING = new HashMap<>();

    private final Map<Class<? extends Service>, Service> instances = new HashMap<>();

    public static void register(String interfaceName, String implName) {
        try {
            Class<?> interfaceType = Class.forName(interfaceName);
            Class<?> implType = Class.forName(implName);
            register(
                    (Class<? extends Service>) interfaceType,
                    (Class<? extends Service>) implType
            );
        } catch (ClassNotFoundException e) {
            String format = String.format("Register failure, interface name is %s, impl name is %s",
                    interfaceName, implName);
            throw new RuntimeException(format, e);
        }
    }

    public static void register(Class<? extends Service> interfaceType,
                                Class<? extends Service> implType) {
        IMPL_MAPPING.put(interfaceType, implType);
    }

    public <IS extends Service> IS getService(Class<IS> innerServiceType) {
        Service innerService = instances.get(innerServiceType);
        if (innerService != null) {
            return (IS) innerService;
        }

        Class<? extends Service> implType = IMPL_MAPPING.get(innerServiceType);
        if (implType == null) {
            throw new RuntimeException(
                    String.format("No service registered for %s.", innerServiceType.getName())
            );
        }

        try {
            IS instance = (IS) implType.newInstance();
            this.instances.put(innerServiceType, instance);
            return instance;
        } catch (Exception e) {
            throw new RuntimeException("Create inner service instance failure.", e);
        }
    }
}