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这篇文章主要介绍“Dubbo的SPI机制介绍以及Activate的使用方法”，在日常操作中，相信很多人在Dubbo的SPI机制介绍以及Activate的使用方法问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”Dubbo的SPI机制介绍以及Activate的使用方法”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
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@SPI
public interface ActivateExt {
String echo(String msg);
}@Activate(group = {"default"})
public class ActivateExtImpl1 implements ActivateExt {
@Override
public String echo(String msg) {
return msg;
}
}
@Activate(group = {"group1", "group2"})
public class GroupActivateExtImpl implements ActivateExt {
@Override
public String echo(String msg) {
return msg;
}
}@Activate(order = 2, group = {"order"})
public class OrderActivateExtImpl1 implements ActivateExt {
@Override
public String echo(String msg) {
return msg;
}
}
@Activate(order = 1, group = {"order"})
public class OrderActivateExtImpl2 implements ActivateExt {
@Override
public String echo(String msg) {
return msg;
}
}@Activate(value = {"value"}, group = {"group"})
public class ValueActivateExtImpl implements ActivateExt {
@Override
public String echo(String msg) {
return msg;
}
}在resources下新建META-INF/dubbo/internal文件夹，新建com.alibaba.dubbo.demo.provider.activate.ActivateExt，即接口的全限定名，文件内容为:
group=com.alibaba.dubbo.demo.provider.activate.impl.GroupActivateExtImpl key=com.alibaba.dubbo.demo.provider.activate.impl.ValueActivateExtImpl order1=com.alibaba.dubbo.demo.provider.activate.impl.OrderActivateExtImpl1 order2=com.alibaba.dubbo.demo.provider.activate.impl.OrderActivateExtImpl2 com.alibaba.dubbo.demo.provider.activate.impl.ActivateExtImpl1
下面是几个单元测试及其测试结果，观察测试结果我们可以得出以下结论：
如果loader.getActivateExtension(URL url, String[] values, String group)中的group参数能够匹配到,就是我们要选择的,test1中根据group=default匹配到了ActivateExtImpl1,它也是在此条件下需要激活的
@Activate中的value是第二层校验参数,第一层是group,在group校验通过的情况下,如果URL中的key参数与类@Activate注解中的value参数一致且key参数对应的值不为空,则才会被选中
order越小,优先级越高
/**
* 1
* class com.alibaba.dubbo.demo.provider.activate.impl.ActivateExtImpl1
*/
@Test
public void test1(){
ExtensionLoader loader = ExtensionLoader.getExtensionLoader(ActivateExt.class);
URL url = URL.valueOf("test://localhost/test");
List list = loader.getActivateExtension(url, new String[]{}, "default");
System.out.println(list.size());
list.forEach(item -> System.out.println(item.getClass()));
} /**
* 1
* class com.alibaba.dubbo.demo.provider.activate.impl.GroupActivateExtImpl
*/
@Test
public void test2(){
ExtensionLoader loader = ExtensionLoader.getExtensionLoader(ActivateExt.class);
URL url = URL.valueOf("test://localhost/test");
List list = loader.getActivateExtension(url, new String[]{}, "group1");
System.out.println(list.size());
list.forEach(item -> System.out.println(item.getClass()));
} /**
* 2
* class com.alibaba.dubbo.demo.provider.activate.impl.OrderActivateExtImpl1
* class com.alibaba.dubbo.demo.provider.activate.impl.ValueActivateExtImpl
*/
@Test
public void test3(){
ExtensionLoader loader = ExtensionLoader.getExtensionLoader(ActivateExt.class);
URL url = URL.valueOf("test://localhost/test");
// 注意这里要使用url接收,不能直接url.addParameter()
url = url.addParameter("value", "test");
List list = loader.getActivateExtension(url, new String[]{"order1", "default"}, "group");
System.out.println(list.size());
list.forEach(item -> System.out.println(item.getClass()));
} /**
* 2
* class com.alibaba.dubbo.demo.provider.activate.impl.OrderActivateExtImpl2
* class com.alibaba.dubbo.demo.provider.activate.impl.OrderActivateExtImpl1
*/
@Test
public void test4(){
ExtensionLoader loader = ExtensionLoader.getExtensionLoader(ActivateExt.class);
URL url = URL.valueOf("test://localhost/test");
List list = loader.getActivateExtension(url, new String[]{}, "order");
System.out.println(list.size());
list.forEach(item -> System.out.println(item.getClass()));
} public void test3(){
ExtensionLoader loader = ExtensionLoader.getExtensionLoader(ActivateExt.class);
URL url = URL.valueOf("test://localhost/test");
// 注意这里要使用url接收,不能直接url.addParameter()
url = url.addParameter("value", "test");
List list = loader.getActivateExtension(url, new String[]{"order1", "default"}, "group");
System.out.println(list.size());
list.forEach(item -> System.out.println(item.getClass()));
}