一、场景模拟
public interface Human {
public void goHome();
}
Human：人类，下班了该回家啦
public interface Car {
void start();
void stop();
void turnLeft();
void turnRight();
}
Car：汽车，可以启动、停止、左转、右转
public class AudiCar implements Car{
public void start() {
System.out.println(this.getClass().getSimpleName() + ": start !!!");
}
public void stop() {
System.out.println(this.getClass().getSimpleName() + ": stop !!!");
}
public void turnLeft() {
System.out.println(this.getClass().getSimpleName() + ": turnLeft !!!");
}
public void turnRight() {
System.out.println(this.getClass().getSimpleName() + ": turnRight !!!");
}
}
AudiCar：奥迪汽车，实现Car
public class BuickCar implements Car{
public void start() {
System.out.println(this.getClass().getSimpleName() + ": start !!!");
}
public void stop() {
System.out.println(this.getClass().getSimpleName() + ": stop !!!");
}
public void turnLeft() {
System.out.println(this.getClass().getSimpleName() + ": turnLeft !!!");
}
public void turnRight() {
System.out.println(this.getClass().getSimpleName() + ": turnRight !!!");
}
}
BuickCar：别克汽车，实现Car
public abstract class HumenWithCar implements Human{
protected final Car car;
public HumenWithCar(Car car) {
this.car = car;
}
public abstract void goHome();
}
HumenWithCar有车一族，实现Human，拥有Car属性
public class Zhang3Human extends HumenWithCar{
public Zhang3Human(Car car) {
super(car);
}
public void goHome() {
car.start();
car.turnLeft();
car.stop();
}
}
Zhang3Human：张三，有车一族
public class Li4Human extends HumenWithCar{
public Li4Human(Car car) {
super(car);
}
public void goHome() {
car.start();
car.turnRight();
car.stop();
}
}
Li4Human：李四，有车一族
二、定义IoC容器
public class IocContrainner {
/**
* 用来存储beans，String为bean的id，Object为bean本身
*/
private final Map<String, Object> beans = new HashMap<String, Object>();
/**
* 根据beanId获取一个bean
* @param beanId beanId
* @return 返回bean
*/
public Object getBean(String beanId) {
return beans.get(beanId);
}
/**
* 委托IoC容器创建一个bean
* @param clazz 要创建的bean的class
* @param beanId beanId
* @param paramBeanIds 要创建的bean的class的构造方法所依赖的bean
*/
public void registerBean(Class<?> clazz, String beanId, String... paramBeanIds) {
Object[] paramValues = new Object[paramBeanIds.length];
for (int i = 0; i < paramBeanIds.length; i++) {
Object paramValue = getBean(paramBeanIds[i]);
if (paramValue == null) {
throw new RuntimeException("Can't find bean of id: " + paramBeanIds[i]);
}
paramValues[i] = paramValue;
}
Object bean = null;
// 获取并循环所有的构造方法
Constructor<?>[] constructors = clazz.getConstructors();
for (Constructor<?> constructor : constructors) {
try {
bean = constructor.newInstance(paramValues);
} catch (InstantiationException e) {
} catch (IllegalAccessException e) {
} catch (InvocationTargetException e) {
}
}
if (bean == null) {
throw new RuntimeException("找不到合适的构造方法：" + paramBeanIds);
}
beans.put(beanId, bean);
}
}
三、测试
public class IocContrainnerTest {
private final IocContrainner iocContrainner = new IocContrainner();
@Before
public void before() {
iocContrainner.registerBean(AudiCar.class, "audi");
iocContrainner.registerBean(PorscheCar.class, "porsche");
iocContrainner.registerBean(BuickCar.class, "buick");
iocContrainner.registerBean(Zhang3Human.class, "zhang3", "audi");
iocContrainner.registerBean(Li4Human.class, "li4", "porsche");
}
@Test
public void test() {
Human zhang3 = (Human) iocContrainner.getBean("zhang3");
zhang3.goHome();
Human li4 = (Human) iocContrainner.getBean("li4");
li4.goHome();
}
}