[JAVA] Simple plugin mechanism in Spring, also consider the order

As a simple plug-in mechanism using Spring, it can be realized very easily as described below.

Simple plug-in mechanism realized by DI container https://blog.ik.am/entries/331

Here, the application order of the plug-ins is also considered. It's very easy to do, just add @Priority to define the order.

MyPlugin.java

public interface MyPlugin {
    String execute();
}

MyPluginService.java

@Service
public class MyPluginService {
    @Autowired
    List<MyPlugin> plugins;

    public List<String> execute() {
        return plugins.stream().map(p -> p.execute()).collect(Collectors.toList());
    }
}

PluginController.java

@RestController
public class PluginController {
    @Autowired
    MyPluginService myPluginService;

    @GetMapping("plugins")
    public List<String> plugins() {
        return myPluginService.execute();
    }
}

@Component
@Priority(10)
public class Fuga1Plugin implements MyPlugin {
    @Override
    public String execute() {
        return "Fuga1Plugin";
    }
}

@Component
@Priority(50)
public class Hoge1Plugin implements MyPlugin {
    @Override
    public String execute() {
        return "Hoge1Plugin";
    }
}

@Component
@Priority(100)
public class Fuga2Plugin implements MyPlugin {
    @Override
    public String execute() {
        return "Fuga2Plugin";
    }
}

@Component
@Priority(200)
public class Hoge2Plugin implements MyPlugin {
    @Override
    public String execute() {
        return "Hoge2Plugin";
    }
}

Execution result

$ curl http://localhost:8080/plugins | jq .
[
  "Fuga1Plugin",
  "Hoge1Plugin",
  "Fuga2Plugin",
  "Hoge2Plugin"
]

By the way, from Spring 4.1, @Priority is recommended instead of @Order. Also, if you use @Conditional, you can write the applicable conditions, but it seems that you will not have much opportunity to use it.