添加 deployer hook

如 OperationStepHandler 实现 中，Subsystem 添加处理器 在 Subsystem 添加时注册了一个 deployer hook

    context.addStep(new AbstractDeploymentChainStep() {
        public void execute(DeploymentProcessorTarget processorTarget) {
            processorTarget.addDeploymentProcessor(SUBSYSTEM_NAME, SubsystemDeploymentProcessor.PHASE, SubsystemDeploymentProcessor.PRIORITY, new SubsystemDeploymentProcessor());
         }
    }, OperationContext.Stage.RUNTIME);

其中 SubsystemDeploymentProcessor 实现了 WildFly deployment 接口 DeploymentUnitProcessor

WildFly deployment API: DeploymentUnitProcessor

public class SubsystemDeploymentProcessor implements DeploymentUnitProcessor {

    @Override
    public void deploy(DeploymentPhaseContext phaseContext) throws DeploymentUnitProcessingException {
        String name = phaseContext.getDeploymentUnit().getName();
        ResourceRoot root = phaseContext.getDeploymentUnit().getAttachment(Attachments.DEPLOYMENT_ROOT);
        TrackerService service = getTrackerService(phaseContext.getServiceRegistry(), name);
        if (service != null) {
            VirtualFile cool = root.getRoot().getChild("META-INF/cool.txt");
            service.addDeployment(name);
            if (cool.exists()) {
                service.addCoolDeployment(name);
            }
        }
    }

    @Override
    public void undeploy(DeploymentUnit context) {
        context.getServiceRegistry();
        String name = context.getName();
        TrackerService service = getTrackerService(context.getServiceRegistry(), name);
        if (service != null) {
            service.removeDeployment(name);
        }
    }

如上代码所示，当 WildFly 执行部署任务时会检查部署的 war/jar/ear 的根目录，如果 META-INF/cool.txt 存在就认为该部署是一个 cool 部署，将其添加到 TrackerService 的 cool 部署列表。

详细实现代码参照 SubsystemDeploymentProcessor.java