Apache骆驼 - 拆分列表，调用API并合并身体

Question

我是Apache Camel的新手，我想问几件事。基本上，我想根据我拥有的资源ID列表来调用API，并将API的所有响应组合到一个消息中。我已经尝试了聚合策略，但似乎并没有起作用。消息主体总是返回API的最后一个响应，并且不会保留旧列表。如果您能给我一些例子，我将非常感谢。

路线

from("file:C:\\Inbound")
//Get resourceID list and split it to call the API
.split(simple("${body}"))
.aggregationStrategy(new ArrayListAggregationStrategy())
.toD("{{api_url}}${body.resourceID}")
.log("After API call ${body}")
.end();

聚合策略

public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {

Object newBody = newExchange.getIn().getBody();

ArrayList<Object> list = null;

if (oldExchange == null) {
    list = new ArrayList<Object>();
    list.add(newBody);
    newExchange.getIn().setBody(list);
    return newExchange;
} else {
    list = oldExchange.getIn().getBody(ArrayList.class);
    list.add(newBody);
    return oldExchange;
}}}

Answer 1

在下面，您将找到一个基本示例，如何使用gentrategy返回Java list的gentrategy实现.split。适用于您的特定情况应该很简单。

doutes.java

import org.apache.camel.builder.RouteBuilder;

public class Routes {
    public static RouteBuilder routes() {
        return
            new RouteBuilder() {
                public void configure() {
                    from("timer:mainRouteTrigger?repeatCount=1")
                    .routeId("MainRouteTrigger")
                        .setBody(constant("100\n200\n300"))
                        .to("direct:mainRoute")
                    .end()
                    ;

                    from("direct:mainRoute")
                    .routeId("MainRoute")
                        .log("MainRoute BEGINS: BODY: ${body}")
                        .split(body().tokenize("\n"), new Aggregator())
                            .to("direct:singleRoute")
                        .end()
                        .log("MainRoute ENDS: BODY: ${body}")
                    .end()
                    ;

                    from("direct:singleRoute")
                    .routeId("SingleRoute")
                        .log("SingleRoute BEGINS: BODY: ${body}")
                        .setBody(simple("this is a response for id ${body}"))
                        .log("SingleRoute ENDS: BODY: ${body}")
                    .end()
                    ;
                }
            };
    }
}

gentregator.java

import org.apache.camel.AggregationStrategy;
import org.apache.camel.Exchange;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Aggregator implements AggregationStrategy {
    @Override
    public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
        // first iteration
        // oldExchange is null
        // body of newExchange is String
        if (oldExchange == null) {
            List<String> newList = buildListFrom(newExchange);
            newExchange.getMessage().setBody(newList, List.class);
            return newExchange;
        }

        // second and subsequent iterations
        // body of oldExchange is List<String>
        // body of newExchange is String
        List<String> oldList = oldExchange.getMessage().getBody(List.class);
        List<String> newList = buildListFrom(newExchange);

        List<String> combined = Stream.concat(oldList.stream(), newList.stream()).collect(Collectors.toList());
        oldExchange.getMessage().setBody(combined);

        return oldExchange;
    }

    private List<String> buildListFrom(Exchange exchange) {
        String body = exchange.getMessage().getBody(String.class);
        List<String> list = new ArrayList<String>();
        list.add(body);
        return list;
    }
}

执行后，记录了以下预期结果：

AbstractCamelContext  INFO  Routes startup (total:3 started:3)
AbstractCamelContext  INFO      Started MainRouteTrigger (timer://mainRouteTrigger)
AbstractCamelContext  INFO      Started MainRoute (direct://mainRoute)
AbstractCamelContext  INFO      Started SingleRoute (direct://singleRoute)
AbstractCamelContext  INFO  Apache Camel 3.14.2 (camel-1) started in 133ms (build:14ms init:105ms start:14ms)
MainSupport           INFO  Waiting until complete: Duration max 5 seconds
MainRoute             INFO  MainRoute BEGINS: BODY: 100
200
300
SingleRoute           INFO  SingleRoute BEGINS: BODY: 100
SingleRoute           INFO  SingleRoute ENDS: BODY: this is a response for id 100
SingleRoute           INFO  SingleRoute BEGINS: BODY: 200
SingleRoute           INFO  SingleRoute ENDS: BODY: this is a response for id 200
SingleRoute           INFO  SingleRoute BEGINS: BODY: 300
SingleRoute           INFO  SingleRoute ENDS: BODY: this is a response for id 300
MainRoute             INFO  MainRoute ENDS: BODY: [this is a response for id 100, this is a response for id 200, this is a response for id 300]
MainSupport           INFO  Duration max seconds triggering shutdown of the JVM
AbstractCamelContext  INFO  Apache Camel 3.14.2 (camel-1) shutting down (timeout:45s)
AbstractCamelContext  INFO  Routes stopped (total:3 stopped:3)
AbstractCamelContext  INFO      Stopped SingleRoute (direct://singleRoute)
AbstractCamelContext  INFO      Stopped MainRoute (direct://mainRoute)
AbstractCamelContext  INFO      Stopped MainRouteTrigger (timer://mainRouteTrigger)
AbstractCamelContext  INFO  Apache Camel 3.14.2 (camel-1) shutdown in 34ms (uptime:5s54ms)

注意是

[this is a response for id 100, this is a response for id 200, this is a response for id 300]

Java list> list已自动转换为字符串通过.log。

Answer 2

如果您想在拆分之后查看结果消息，则必须在.log（...）语句 .end> .end> .end（）'split＆amp;加入'过程。

为了更好的清晰度，我建议您缩进您的代码，例如：

.split(simple("${body}"))
  .aggregationStrategy(new ArrayListAggregationStrategy())
  .toD("{{api_url}}${body.resourceID}")
  .log("Individual API call response: ${body}")
.end()
.log("Complete aggregation result: ${body}");