Java 如何仅在不同包中的另一个类中限制类的可见性？
我的项目中有以下包和类结构Java 如何仅在不同包中的另一个类中限制类的可见性？,java,package,java-6,java-package,Java,Package,Java 6,Java Package,我的项目中有以下包和类结构 package de.mycompany.jakarta.order; import de.mycompany.ordermanagement.order.OrderCancellationService; public class DrugOrderManager { private static final DrugOrderManager INSTANCE = new DrugOrderManager(); private DrugOrderManager()
package de.mycompany.jakarta.order;
import de.mycompany.ordermanagement.order.OrderCancellationService;
public class DrugOrderManager {
private static final DrugOrderManager INSTANCE = new DrugOrderManager();
private DrugOrderManager() {
}
public static DrugOrderManager getInstance() {
return INSTANCE;
}
public void cancelOrder() {
OrderCancellationService.getInstance().process();
} }
package de.mycompany.ordermanagement.order;
public class OrderCancellationService {
private static OrderCancellationService INSTANCE = new OrderCancellationService();
private OrderCancellationService() {
}
public static OrderCancellationService getInstance() {
return INSTANCE;
}
public void process() {
} }
我的意图是OrderCancellationService应该只由DrugOrderManager调用，任何其他类/服务都不应该直接调用它。我试图使DrugOrderManager成为所有服务的网关。如何限制此可见性？请建议若要执行所需操作，只需在
DrugOrderManagerOrderCancellationServiceOrderCancellationServiceDrugOrderManager如果您不能移动类，那么我想Java中没有解决方案。要想做您想做的事情，您只需在
DrugOrderManagerOrderCancellationServiceOrderCancellationServiceDrugOrderManager如果您不能移动类，那么我猜Java中没有解决方案。您可以尝试在DrugOrderManager中将OrderCancellationService定义为私有类，也许这会如您所期望的那样起作用….您可以尝试在DrugOrderManager中将OrderCancellationService定义为私有类，也许这会像你期望的那样起作用……有几种明显而糟糕的方法可以做到这一点：
- 使OrderCancellationService成为DrugOrderManager中的私有类
- 将OrderCancellationService和DrugOrderManager放在同一个包中
class Factory {
private static Map<Class, Object> INSTANCES = new HashMap<>();
private ServiceA serviceA;
private ServiceB serviceB;
public static void register(Class clazz, Object instance) {
instances.put(clazz, instance);
}
static {
Class.forName("ServiceA");
Class.forName("ServiceB");
serviceA = (ServiceA)(INSTANCES.get(ServiceA.class));
serviceB = (ServiceB)(INSTANCES.get(ServiceB.class));
serviceB.setServiceA(serviceA);
}
}
class ServiceB {
private ServiceB INSTANCE = new ServiceB();
private ServiceA serviceA;
private ServiceB() {}
public setServiceA(ServiceA serviceA) {
this.serviceA = serviceA;
}
static {
Factory.register(ServiceB.class, INSTANCE);
}
}
Spring（）实际上是Java世界中的标准。你应该在网上查看一些全套短裙/训练，看看它能做些什么。有几种明显和不好的方法可以做到这一点：
- 使OrderCancellationService成为DrugOrderManager中的私有类
- 将OrderCancellationService和DrugOrderManager放在同一个包中
class Factory {
private static Map<Class, Object> INSTANCES = new HashMap<>();
private ServiceA serviceA;
private ServiceB serviceB;
public static void register(Class clazz, Object instance) {
instances.put(clazz, instance);
}
static {
Class.forName("ServiceA");
Class.forName("ServiceB");
serviceA = (ServiceA)(INSTANCES.get(ServiceA.class));
serviceB = (ServiceB)(INSTANCES.get(ServiceB.class));
serviceB.setServiceA(serviceA);
}
}
class ServiceB {
private ServiceB INSTANCE = new ServiceB();
private ServiceA serviceA;
private ServiceB() {}
public setServiceA(ServiceA serviceA) {
this.serviceA = serviceA;
}
static {
Factory.register(ServiceB.class, INSTANCE);
}
}