Apache 骆驼聚合给出异常

Question

关于问题：

提示我无法通过拆分方法获取字符串列表，所以我尝试了如下聚合方法：

public class lowestRates implements AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
    String oldStr = oldExchange.getIn().getBody(String.class);
    String newStr = newExchange.getIn().getBody(String.class);
    Pattern p = Pattern.compile("(\w+)\s(\d+)");
    Matcher m1 = p.matcher(oldStr);
    Matcher m2 = p.matcher(newStr);
    String finalStr = "";
    if(m1.group(2).equalsIgnoreCase(m2.group(2)))
        finalStr = m1.group(1) + Integer.toString(Integer.parseInt(m1.group(2)) > Integer.parseInt(m2.group(2)) ? Integer.parseInt(m2.group(2)) : Integer.parseInt(m1.group(2)));
    else
        finalStr = oldStr + "\n" + newStr;
    oldExchange.getIn().setBody(finalStr);
    return oldExchange;
}

}

和新的主要代码：

from("file://files")
                    .split()
                    .tokenize("\n")
                    .aggregate(new lowestRates())
                    .body()
                    .completionTimeout(5000)
                    .to("file://files/result.txt")

但它给了我：

org.apache.camel.CamelExchangeException: Error occurred during aggregation. Exchange[][Message: Good1 450]. Caused by: [java.lang.NullPointerException - null]

现在的问题是如何编写正确的聚合方法，因为我看不出这里有什么错误:(。

Answer 1

String oldStr = oldExchange.getIn().getBody(String.class);
String newStr = newExchange.getIn().getBody(String.class);

您需要在此处检查字符串是否为 null.. 对于第一条消息，oldStr 将为空。恕我直言，您收到异常然后尝试解析空字符串。是的，检查 null

的交换

    if (oldExchange == null) {
        return newExchange;
    }

更新：像这样尝试：

public class lowestRates implements AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
    if (oldExchange == null) {
        return newExchange;
    }
    if (newExchange.getIn().getBody()!=null){
       Pattern p = Pattern.compile("(\w+)\s(\d+)");
       String finalStr = ""; 
       String oldStr = oldExchange.getIn().getBody(String.class);
       String newStr = newExchange.getIn().getBody(String.class);
       if (oldStr!=null&&newStr!=null){
       Matcher m1 = p.matcher(oldStr);
       Matcher m2 = p.matcher(newStr);

          if(m1.group(2).equalsIgnoreCase(m2.group(2)))
            finalStr = m1.group(1) + Integer.toString(Integer.parseInt(m1.group(2)) > Integer.parseInt(m2.group(2)) ? Integer.parseInt(m2.group(2)) : Integer.parseInt(m1.group(2)));
          else
            finalStr = oldStr + "\n" + newStr;
          }

      oldExchange.getIn().setBody(finalStr);
      }
      return oldExchange;
    }
}

还需要修改聚合如下，

发件人：

Aggregate(new strategy()).body() //This is where things go wrong

收件人：

Aggregate(constant(true), new strategy()).completionFromBatchConsumer()

Apache 骆驼聚合给出异常

Apache camel aggregate gives exception

java

apache-camel