骆驼豆参数绑定不起作用

Question

I'm learning Apache Camel framework, trying to implement simple bean parameter binding example.

I have the following route

from("timer://foo?delay=2000")
    .setBody(simple("hello"))
    .log("${body}")
    .transform(simple("<foo>${body}</foo>"))
    .log("${body}")
    .bean(DocumentProcessorBean.class, "process");

And the following Spring bean

@Component("documentProcessorBean")
public static class DocumentProcessorBean {

    public Document process(@Body Document doc, @Headers Map<String, Object> headers) {
        System.out.println(doc);
        System.out.println(headers);
        return doc;
    }
}

However, the parameter binding doesn't seem to work, as I'm getting Document instance without content, as is shown in the log

2018-04-03 18:14:39.354  INFO 7740 --- [1 - timer://foo] route1                                   : hello
2018-04-03 18:14:39.354  INFO 7740 --- [1 - timer://foo] route1                                   : <foo>hello</foo>
[#document: null]
{breadcrumbId=ID-DESKTOP-LI5P50P-1522768469501-0-6, firedTime=Tue Apr 03 18:14:39 EEST 2018}

I'm also confused about the "implicit" data formats camel uses. For example, does transformation using simple always return a string? What is the difference of using string, marshalled format (eg xstream) or binding class format (POJO) in the route, or does it even matter? Generally, what are the scenarios when I need to transform between these formats in the route? And most importantly, why the bean parameter binding in this particular route doesn't work?

Answer 1

You cannot just System.out.println a Document instance and have it show the XML content. What you see in the log is expected, it may just show Document: null or something, but that does not mean there is no content.

Answer 2

If you are facing a "parameter bean binding exception then use object mapper here", replace the commented highlighted code with the below one and autowired the object mapper instance: