为什么 fileNameSet 为空？

Question

我是 Talend 的新手，我正在创建一个 bean，以将四条消息聚合为一条。我正在使用 cFile 组件，它使用目录中的 4 个文件，然后是聚合器，然后是处理器。聚合Bean的代码如下：

package beans;

import java.util.HashSet;
import java.util.Set;

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

public class AggregateBody implements AggregationStrategy{

public Exchange aggregate(Exchange oldEx, Exchange newEx) {
    Set<String> fileNameSet =  new HashSet<String>();
    Set<String> bodySet =  new HashSet<String>();
    if(oldEx==null){
        fileNameSet.add((String) newEx.getIn().getHeader("fileName"));
        bodySet.add(newEx.getIn().getBody(String.class));
        newEx.setProperty("fileName",fileNameSet);
        System.out.println(fileNameSet);

        newEx.setProperty("body",bodySet);
        System.out.println(bodySet);
        return newEx;
    }

    oldEx.getProperty("fileName",fileNameSet);
    fileNameSet.add((String) oldEx.getIn().getHeader("fileName"));
    oldEx.setProperty("fileName",fileNameSet);
    System.out.println(fileNameSet);

    oldEx.getProperty("body",bodySet);
    bodySet.add(oldEx.getIn().getBody(String.class));
    oldEx.setProperty("body",bodySet);
    return oldEx;
}

}

所以我不明白为什么 fileName 的系统输出是 [null]。

Answer 1

得到空文件名的原因是，filenameset 没有更新。代码应该是这样的：

package beans;

import java.util.ArrayList;
import java.util.List;

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

public class AggregateBody implements AggregationStrategy {

@SuppressWarnings("unchecked")
public Exchange aggregate(Exchange oldEx, Exchange newEx) {
    List<String> fileNameSet = new ArrayList<String>();
    List<String> bodySet = new ArrayList<String>();
    if (oldEx == null) {
        fileNameSet.add((String) newEx.getIn().getHeader("CamelFileName"));
        newEx.setProperty("CamelFileName", fileNameSet);
        bodySet.add(newEx.getIn().getBody(String.class));
        newEx.setProperty("body", bodySet);
        return newEx;
    }

    fileNameSet = (List<String>) oldEx.getProperty("CamelFileName", fileNameSet);
    bodySet = (List<String>) oldEx.getProperty("body", bodySet);

    fileNameSet.add((String) newEx.getIn().getHeader("CamelFileName"));

    bodySet.add(newEx.getIn().getBody(String.class));
    oldEx.setProperty("CamelFileName", fileNameSet);
    oldEx.setProperty("body", bodySet);
    return oldEx;
}

}

为什么 fileNameSet 为空？

Why fileNameSet is null?

jms

apache-camel

talend

java-7