flow - 拦截器（FlowInterceptor）

在流程引擎身上附加拦截器，可实现计时、异常控制、上下文参数调整等。

1、使用示例

组件注解模式

import org.noear.solon.annotation.Component;
import org.noear.solon.flow.intercept.FlowInterceptor;
import org.noear.solon.flow.intercept.FlowInvocation;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component
public class FlowInterceptorImpl implements FlowInterceptor {
    static Logger log = LoggerFactory.getLogger(ChainInterceptorImpl.class);

    @Override
    public void doIntercept(FlowInvocation inv) throws Throwable {
        long start = System.currentTimeMillis();
        try {
            inv.invoke();
        } catch (Throwable ex) {
            log.error("Graph eval failure: " + inv.getStartNode().getGraph().getId(), ex);
        } finally {
            long end = System.currentTimeMillis();
            System.out.println(end - start);
        }
    }
}

原生 java 模式:

flowEngine.addInterceptor(new FlowInterceptorImpl());

2、FlowInterceptor 接口参考

public interface FlowInterceptor {
    /**
     * 拦截执行
     *
     * @param invocation 调用者
     */
    void doIntercept(FlowInvocation invocation) throws FlowException;

    /**
     * 节点运行开始时
     *
     * @since 3.4
     */
    default void onNodeStart(FlowContext context, Node node) {

    }

    /**
     * 节点运行结束时
     *
     * @since 3.4
     */
    default void onNodeEnd(FlowContext context, Node node) {

    }
}