301.7. 샘플

Servlet Tomcat 예제 를 참조하십시오.

Camel/Spring 애플리케이션에서 Servlet 구성 요소를 사용할 때 Servlet 구성 요소가 시작된 후 Spring ApplicationContext를 로드해야 하는 경우가 많습니다. 이 작업은 ContextLoaderListener 대신 Spring의 ContextLoaderServlet 을 사용하여 수행할 수 있습니다. 이 경우 다음과 같이 CamelHttpTransportServlet 을 시작한 후 ContextLoaderServlet 을 시작해야 합니다.

<web-app>
  <servlet>
        <servlet-name>CamelServlet</servlet-name>
        <servlet-class>
            org.apache.camel.component.servlet.CamelHttpTransportServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet>
        <servlet-name>SpringApplicationContext</servlet-name>
        <servlet-class>
            org.springframework.web.context.ContextLoaderServlet
        </servlet-class>
        <load-on-startup>2</load-on-startup>
  </servlet>
<web-app>

Camel 2.6.0 에서는 다음과 같이 블루프린트를 사용하여 CamelHttpTransportServlet 을 OSGi 서비스로 게시할 수 있습니다.

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="
           http://www.osgi.org/xmlns/blueprint/v1.0.0 https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">

    <bean id="camelServlet" class="org.apache.camel.component.servlet.CamelHttpTransportServlet" />

    <!--
        Enlist it in OSGi service registry.
        This will cause two things:
        1) As the pax web whiteboard extender is running the CamelServlet will
           be registered with the OSGi HTTP Service
        2) It will trigger the HttpRegistry in other bundles so the servlet is
           made known there too
    -->
    <service ref="camelServlet">
        <interfaces>
            <value>javax.servlet.Servlet</value>
            <value>org.apache.camel.http.common.CamelServlet</value>
        </interfaces>
        <service-properties>
            <entry key="alias" value="/camel/services" />
            <entry key="matchOnUriPrefix" value="true" />
            <entry key="servlet-name" value="CamelServlet" />
        </service-properties>
    </service>

</blueprint>

그런 다음 다음과 같이 Camel 경로에서 이 서비스를 사용합니다.

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:ext="http://aries.apache.org/blueprint/xmlns/blueprint-ext/v1.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="
           http://www.osgi.org/xmlns/blueprint/v1.0.0 https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">

    <reference id="servletref" ext:proxy-method="classes" interface="org.apache.camel.http.common.CamelServlet">
        <reference-listener ref="httpRegistry" bind-method="register" unbind-method="unregister" />
    </reference>

    <bean id="httpRegistry" class="org.apache.camel.component.servlet.DefaultHttpRegistry" />

    <bean id="servlet" class="org.apache.camel.component.servlet.ServletComponent">
        <property name="httpRegistry" ref="httpRegistry" />
    </bean>

    <bean id="servletProcessor" class="org.apache.camel.example.servlet.ServletProcessor" />

    <camelContext xmlns="http://camel.apache.org/schema/blueprint">
        <route>
            <!-- Notice how we can use the servlet scheme which is that reference above -->
            <from uri="servlet://hello" />
            <process ref="servletProcessor" />
        </route>
    </camelContext>

</blueprint>

Camel 2.6 이전 버전의 경우 Activator 를 사용하여 CamelHttpTransportServlet 을 OSGi 플랫폼에 게시할 수 있습니다.

import java.util.Dictionary;
import java.util.Hashtable;

import org.apache.camel.component.servlet.CamelHttpTransportServlet;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.http.HttpContext;
import org.osgi.service.http.HttpService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.osgi.context.BundleContextAware;

public final class ServletActivator implements BundleActivator, BundleContextAware {
    private static final Logger LOG = LoggerFactory.getLogger(ServletActivator.class);
    private static boolean registerService;

    /**
     * HttpService reference.
     */
    private ServiceReference<?> httpServiceRef;

    /**
     * Called when the OSGi framework starts our bundle
     */
    public void start(BundleContext bc) throws Exception {
        registerServlet(bc);
    }

    /**
     * Called when the OSGi framework stops our bundle
     */
    public void stop(BundleContext bc) throws Exception {
        if (httpServiceRef != null) {
            bc.ungetService(httpServiceRef);
            httpServiceRef = null;
        }
    }

    protected void registerServlet(BundleContext bundleContext) throws Exception {
        httpServiceRef = bundleContext.getServiceReference(HttpService.class.getName());

        if (httpServiceRef != null && !registerService) {
            LOG.info("Register the servlet service");
            final HttpService httpService = (HttpService)bundleContext.getService(httpServiceRef);
            if (httpService != null) {
                // create a default context to share between registrations
                final HttpContext httpContext = httpService.createDefaultHttpContext();
                // register the hello world servlet
                final Dictionary<String, String> initParams = new Hashtable<String, String>();
                initParams.put("matchOnUriPrefix", "false");
                initParams.put("servlet-name", "CamelServlet");
                httpService.registerServlet("/camel/services", // alias
                    new CamelHttpTransportServlet(), // register servlet
                    initParams, // init params
                    httpContext // http context
                );
                registerService = true;
            }
        }
    }

    public void setBundleContext(BundleContext bc) {
        try {
            registerServlet(bc);
        } catch (Exception e) {
            LOG.error("Cannot register the servlet, the reason is " + e);
        }
    }

}

Camel 2.19.0 이후의 camel-servlet-starter 라이브러리는 /camel/* 컨텍스트 경로 아래의 나머지 모든 끝점을 자동으로 바인딩합니다. 다음 표에는 camel-servlet-starter 라이브러리에서 사용할 수 있는 추가 구성 속성이 요약되어 있습니다. Camel 서블릿의 자동 매핑을 비활성화할 수도 있습니다.