74.10. 使用标头作为输入

from("direct:start")
    .setHeader("numberOfBooks")
        .jsonpath("$..store.book.length()", false, int.class, "books")
    .to("mock:result");

from("direct:start")
    .setHeader("numberOfBooks")
        .jsonpath("$..store.book.length()", false, int.class, "books")
    .to("mock:result");

<route>
  <from uri="direct:start"/>
  <setHeader name="numberOfBooks">
    <jsonpath headerName="books" resultType="int">$..store.book.length()</jsonpath>
  </setHeader>
  <to uri="mock:result"/>
</route>

<route>
  <from uri="direct:start"/>
  <setHeader name="numberOfBooks">
    <jsonpath headerName="books" resultType="int">$..store.book.length()</jsonpath>
  </setHeader>
  <to uri="mock:result"/>
</route>