工厂方法模式定义

工厂方法模式（Fatory Method Pattern）是指定义一个创建对象的接口，但让实现这个接口的类来决定实例化哪个类，工厂方
法让类的实例化推迟到子类中进行。

Define an interface for creating an object, but let subclasses decide which class to instantiate. The Factory method lets a class defer instantiation it uses to subclasses.

属于创建型设计模式。

public interface ICourseFactory {

    ICourse create();

}

public class JavaCourseFactory implements ICourseFactory {
    public ICourse create() {
        return new JavaCourse();
    }
}

public class PythonCourseFactory implements ICourseFactory {

    public ICourse create() {
        return new PythonCourse();
    }
}

public class FactoryMethodTest {

    public static void main(String[] args) {

        ICourseFactory factory = new PythonCourseFactory();
        ICourse course = factory.create();
        course.record();

        factory = new JavaCourseFactory();
        course = factory.create();
        course.record();

    }

}

LoggerFactory.getLogger(FactoryMethodTest.class);

public static Logger getLogger(Class clazz) {
    return getLogger(clazz.getName());
}

  public static Logger getLogger(String name) {
    ILoggerFactory iLoggerFactory = getILoggerFactory();
    return iLoggerFactory.getLogger(name);
  }

  public static ILoggerFactory getILoggerFactory() {
    if (INITIALIZATION_STATE == UNINITIALIZED) {
      INITIALIZATION_STATE = ONGOING_INITIALIZATION;
      performInitialization();
    }
    switch (INITIALIZATION_STATE) {
      case SUCCESSFUL_INITIALIZATION:
        return StaticLoggerBinder.getSingleton().getLoggerFactory();
      case NOP_FALLBACK_INITIALIZATION:
        return NOP_FALLBACK_FACTORY;
      case FAILED_INITIALIZATION:
        throw new IllegalStateException(UNSUCCESSFUL_INIT_MSG);
      case ONGOING_INITIALIZATION:
        // support re-entrant behavior.
        // See also http://bugzilla.slf4j.org/show_bug.cgi?id=106
        return TEMP_FACTORY;
    }
    throw new IllegalStateException("Unreachable code");
  }