探究Dubbo的拓展机制: 上

# 描述 Dubbo 协议的服务
Dubbo://192.168.1.6:20880/moe.cnkirito.sample.HelloService?timeout=3000
# 描述 zookeeper 注册中心
zookeeper://127.0.0.1:2181/org.apache.Dubbo.registry.RegistryService?application=demo-consumer&Dubbo=2.0.2&interface=org.apache.Dubbo.registry.RegistryService&pid=1214&qos.port=33333&timestamp=1545721981946
# 描述消费者 服务
consumer://30.5.120.217/org.apache.Dubbo.demo.DemoService?application=demo-consumer&category=consumers&check=false&Dubbo=2.0.2&interface=org.apache.Dubbo.demo.DemoService&methods=sayHello&pid=1209&qos.port=33333&side=consumer&timestamp=1545721827784
# for this case, url protocol = null, url host = 192.168.1.3, port = 20880, url path = null
192.168.1.3:20880
# for this case, url protocol = file, url host = null, url path = home/user1/router.js
file:///home/user1/router.js?type=script
... 更多参照URL源码

// 接口
public interface Person {
    String getName();
}
// 实现类一: 
public class Student implements Person {
    @Override
    public String getName() {
        return "Student";
    }
}
//  实现类二: 
public class Teacher implements Person {
    @Override
    public String getName() {
        return "Teacher";
    }
}

com.changwu.javaspi.api.Student
com.changwu.javaspi.api.Teacher

public class Test {
    public static void main(String[] args) {
        // 加载接口中的实现类
        ServiceLoader<Person> load = ServiceLoader.load(Person.class);
        Iterator<Person> iterator = load.iterator();
        while (iterator.hasNext()){
            Person next = iterator.next();
            System.out.println(next.getName());
        }
    }
}

Student
Teacher

@SPI
public interface PersonInterface {
   String getName();
}

public class Student implements PersonInterface {
    @Override
    public String getName() {
        return "Student";
    }
}
public class Teacher implements PersonInterface {
    @Override
    public String getName() {
        return "Teacher";
    }
}

public class Test {
    public static void main(String[] args) {
        // todo 第一点:  Dubbo 的SPI算作是他的一个可扩展的机制
        ExtensionLoader<PersonInterface> extensionLoader = ExtensionLoader.getExtensionLoader(PersonInterface.class);
        PersonInterface personInterface = extensionLoader.getExtension("student");
        System.out.println(personInterface.getName());
    }
}

public class Human implements PersonInterface {
    private PersonInterface personInterface;
    public void setpersonInterface(PersonInterface personInterface) {
        this.personInterface = personInterface;
    }
    @Override
    public String getColor(URL url) {
        System.out.println("i am Human ");
        return "i am Human + " + personInterface.getColor(url);
    }
}

public class Test {
    public static void main(String[] args) {
        // todo 源码的入口, 进入 getExtensionLoader()
        ExtensionLoader extensionLoader = ExtensionLoader.getExtensionLoader(PersonInterface.class);
        HashMap<String, String> map = new HashMap<>();
        map.put("human", "student");
        URL url = new URL("", "",1,map);
        // todo 继续跟进这个方法
        PersonInterface personInterface = (PersonInterface) extensionLoader.getExtension("human");
        System.out.println(personInterface.getName(url));
    }
}

// @SPI("stu") 可以给注解添加参数, 参数表示 PersonInterface 的默认实现类
@SPI
public interface PersonInterface {
    // todo 下面的注解很重要, 啥意思呢?  可以点进这个注解, 我有一些翻译
    // 验证AOP, 依然注入的信息从 url中获取出来
    @Adaptive("human")
    String getName(URL url);
}

public class PersonWrapper implements PersonInterface {
    // todo 验证Dubbo的自动注入
    private PersonInterface personInterface;
    // todo 根据构造方法进行注入
    public PersonWrapper(PersonInterface in){ // 假设传递进来的就是具体的实现类
        this.personInterface=in;
    }
    // todo 当我们将 personWrapper 配置进 Dubbo的 spi中时, 通过Dubbo的Spi获取personInterface执行时,下面的方法就会被执行
    @Override
    public String getName() {
        System.out.println("before... ");
        String color = personInterface.getName();
        System.out.println("after... ");
        return "getName";
    }
}

public static void main(String[] args) {
        // todo 第一点:  Dubbo 的SPI算作是他的一个可扩展的机制
        ExtensionLoader<PersonInterface> extensionLoader = ExtensionLoader.getExtensionLoader(PersonInterface.class);
        PersonInterface personInterface = extensionLoader.getExtension("student");
        System.out.println(personInterface.getName());
    }

before...
after...
getName