Apache Camel XPath with nodelist

问题

I would like to concatenate all values from the Apache Camel XPath result and add it to the message context. The header should look like: "|value1|value2|valueN|"

My route looks like:

from("direct:test")
.setHeader("key").xpath("//Identifier", List.class)
.to("mock:result")

What is the best way for doing that? Is there a way to implement an own result type?

Thanks

回答1:

As Willem said, you have to write your own processor.

For such a little thing, my favourite way is to declare a function in the class containing the route definition returning an anonymous Processor like this:

private Processor setHeaderWithIdentifiers() {
    return new Processor() {
        @Override
        public void process(Exchange exchange) throws Exception {
            List<String> identifiers = new ArrayList<>();
            NodeList nodes = XPathBuilder.xpath("//Identifier").evaluate(exchange,  NodeList.class);

            for (int i = 0; i < nodes.getLength(); i++) {
                identifiers.add(nodes.item(i).getNodeValue());
            }

            // StringUtils from Apache Commons 3 
            String idAsString = StringUtils.join(identifiers, "|");
            exchange.getIn().setHeader("key", idAsString);
        }
    };
}

With that, you do not need to find any complex Xpath functions and the code remains clear to understand as long the Processor code remains short.

来源：https://stackoverflow.com/questions/20529197/apache-camel-xpath-with-nodelist