PicoContainer-Two minute tutorial
转自:http://www.picocontainer.org/Two+minute+tutorial
Two minute tutorial
两分钟教程
Authors: [url=http://www.picocontainer.org/display/~tirsen]Jon Tirsen
This very short tutorial should get you up to speed with PicoContainer in 2 minutes. It does not go into why you should do it, read the Five minute introduction for that.
这是一个非常简短的是你能够快速掌握微容器的两分钟教程.如果它仍然不能是你确定为什么要使用微容器,你可以继续阅读5分钟介绍.
Download and install
Download the jar file and include it in your classpath.
Write two simple components
两个简单的组件
public class Boy {
public void kiss(Object kisser) {
System.out.println("I was kissed by " + kisser);
}
}
public class Girl {
Boy boy;
public Girl(Boy boy) {
this.boy = boy;
}
public void kissSomeone() {
boy.kiss(this);
}
}
Assemble components
装配组件
MutablePicoContainer pico = new DefaultPicoContainer();
pico.registerComponentImplementation(Boy.class);
pico.registerComponentImplementation(Girl.class);
Instantiate and use component
初始化并使用组件
Girl girl = (Girl) pico.getComponentInstance(Girl.class);
girl.kissSomeone();
getComponentInstance will look at the Girl class and determine that it needs to create a Boy instance and pass that into the constructor to create a Girl. The Boy is created and then the Girl.
getComponentInstance方法将会查找Girl类和匹配Boy类并创建它然后传入构造方法初始化一个Girl实例.先创建的Boy然后是Girl.
Girl类没有自己去调用这个Boy类而是通过容器提供的,这就是著名的好莱坞规则“不要找我,我会找你的“.
Introduce an interface for the dependency
给从属类一个接口
Change the Boy class to implement a Kissable interface and change the Girl class to depend on Kissable instead.
将Boy类实现一个Kissable接口并且改变Girl类去引用一个Kissable对象.
public interface Kissable {
void kiss(Object kisser);
}
public class Boy implements Kissable {
public void kiss(Object kisser) {
System.out.println("I was kissed by " + kisser);
}
}
public class Girl {
Kissable kissable;
public Girl(Kissable kissable) {
this.kissable = kissable;
}
public void kissSomeone() {
kissable.kiss(this);
}
}
Assemble and use components just as before:
和前面一样去装配组件:
MutablePicoContainer pico = new DefaultPicoContainer();
pico.registerComponentImplementation(Boy.class);
pico.registerComponentImplementation(Girl.class);
Now run:
现在运行:
Girl girl = (Girl) pico.getComponentInstance(Girl.class);
girl.kissSomeone();
The Girl will be given a Boy, because PicoContainer understands that it is a Kissable
Girl会自动接到一个Boy类型,因为微容器知道Boy是一个Kissable的对象
Girl和Boy没有任何依赖关系,这就是Dependency Inversion Principle,也就是依赖接口而不直接存在依赖关系.
Use simple lifecycle
使用简单的生命周期控制
Change the Girl class to implement the simple default lifecycle and do it's kissing when the container is started.
改变Girl类,实现默认的生命周期控制类,并且是他在容器启动是就“kissing“
public class Girl implements Startable {
Kissable kissable;
public Girl(Kissable kissable) {
this.kissable = kissable;
}
public void start() {
kissable.kiss(this);
}
public void stop() {
}
}
Assemble container as before but instead of calling the Girl directly just start the container like this:
象以前一样装配容器,但是不需要直接调用Girl的方法,只需要启动容器即可:
pico.start();
This will instantiate all components that implement Startable and call the start method on each of them. To stop and dispose the container do as follows:
这个方法会调用所有实现了Startable的组件,并调用他们的start方法.停止他们就可以使用一下的方法了:
pico.stop();
pico.dispose();
