[置顶] Spring Integration实例代码分析之basic--http

从spring官方网站下载Spring Integration的例子代码，里面包含了很多个分好类的例子

下载地址：https://github.com/SpringSource/spring-integration-samples

打开basic文件夹，里面有一个http的例子

1.导入项目

我们可以在eclipse里进行调试，由于这些例子都是用maven构建的，最好先给eclipse安装maven插件，以及maven的wtp插件（用于WEB开发）

安装方式：eclipse-->help-->eclipemarketplace 搜索maven

安装前两个就行了

之后导入http这个例子的代码，eclipse-->import-->existing maven projects,

选择http文件夹（包含pom.xml的文件夹都可以导入）即可导入此项目，maven会自动去下载所需的依赖包，目录结构如下图：

2.代码分析

服务器端的代码

首先，从目录可见，这是一个WEB项目，可以部署到WEB容器中，我们先看服务器端的代码

分析一下web.xml文件，

web.xml

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>multipart-http</display-name>
  <servlet>
    <servlet-name>Multipart</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>/WEB-INF/servlet-config.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Multipart</servlet-name>
    <url-pattern>/*</url-pattern>
  </servlet-mapping>
</web-app>

其中配置了一个servlet,名字叫Multipart,配置的类为DispatcherServlet,用过SPRING MVC的都比较熟悉这个配置，它就是SPRING表示层的控制器。

其contextConfigLocation配置的是/WEB-INF/servlet-config.xml

我们再看一下servlet-config.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
		http://www.springframework.org/schema/integration/file http://www.springframework.org/schema/integration/file/spring-integration-file.xsd
		http://www.springframework.org/schema/integration/http http://www.springframework.org/schema/integration/http/spring-integration-http.xsd"
	xmlns:int="http://www.springframework.org/schema/integration"
	xmlns:int-file="http://www.springframework.org/schema/integration/file"
	xmlns:int-http="http://www.springframework.org/schema/integration/http"
	xmlns:int-mail="http://www.springframework.org/schema/integration/mail">

	<int-http:inbound-gateway request-channel="receiveChannel"
                          name="/receiveGateway"
                          supported-methods="POST,GET"/>
                          
	<int:channel id="receiveChannel"/>	
	
	<int:service-activator input-channel="receiveChannel" expression="payload + ' from the other side'"/>
</beans>

配置了一个int-http:inbound-gateway，channel和一个service-activator，inbound-gateway用来接受请求，关联名称/receiveGateway，接受POST GET请求，并连接到一个通道，为receiveChannel，通道关联到一个service-activator，表达式为payload + from the other side,其中payload为从客户端接受的信息，添加一些信息之后返回去。

服务器端就是这么简单的内容，用spring的eclipse插件打开这个文件，可以看到图示：

我们可以将服务器端运行起来，选择pom右键-->run as-->maven build

在goal输入jetty:run，确定即可。

输出信息如下：

[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] <<< maven-jetty-plugin:6.1.10:run (default-cli) @ http <<<
[WARNING] The artifact org.apache.commons:commons-io:jar:1.3.2 has been relocated to commons-io:commons-io:jar:1.3.2
[INFO]
[INFO] --- maven-jetty-plugin:6.1.10:run (default-cli) @ http ---
[INFO] Configuring Jetty for project: Samples (Basic) - HTTP Demo
[INFO] Webapp source directory = /media/g_windows/ubuntudata/code/SpringSource-spring-integration-samples-84aefe6/basic/http/src/main/webapp
[INFO] web.xml file = /media/g_windows/ubuntudata/code/SpringSource-spring-integration-samples-84aefe6/basic/http/src/main/webapp/WEB-INF/web.xml
[INFO] Classes = /media/g_windows/ubuntudata/code/SpringSource-spring-integration-samples-84aefe6/basic/http/target/classes
2012-10-25 15:15:37.729::INFO: Logging to STDERR via org.mortbay.log.StdErrLog
[INFO] Context path = /http
[INFO] Tmp directory = determined at runtime
[INFO] Web defaults = org/mortbay/jetty/webapp/webdefault.xml
[INFO] Web overrides = none
[INFO] Webapp directory = /media/g_windows/ubuntudata/code/SpringSource-spring-integration-samples-84aefe6/basic/http/src/main/webapp
[INFO] Starting jetty 6.1.10 ...
2012-10-25 15:15:37.823::INFO: jetty-6.1.10
2012-10-25 15:15:37.201::INFO: No Transaction manager found - if your webapp requires one, please configure one.
2012-10-25 15:15:38.179:/http:INFO: Initializing Spring FrameworkServlet 'Multipart'
15:15:38.803 INFO [main][org.springframework.web.servlet.DispatcherServlet] FrameworkServlet 'Multipart': initialization started
15:15:38.862 INFO [main][org.springframework.web.context.support.XmlWebApplicationContext] Refreshing WebApplicationContext for namespace 'Multipart-servlet': startup date [Thu Oct 25 15:15:38 CST 2012]; root of context hierarchy
15:15:38.927 INFO [main][org.springframework.beans.factory.xml.XmlBeanDefinitionReader] Loading XML bean definitions from ServletContext resource [/WEB-INF/servlet-config.xml]
15:15:39.712 INFO [main][org.springframework.integration.config.xml.DefaultConfiguringBeanFactoryPostProcessor] No bean named 'errorChannel' has been explicitly defined. Therefore, a default PublishSubscribeChannel will be created.
15:15:39.712 INFO [main][org.springframework.integration.config.xml.DefaultConfiguringBeanFactoryPostProcessor] No bean named 'taskScheduler' has been explicitly defined. Therefore, a default ThreadPoolTaskScheduler will be created.
15:15:39.734 INFO [main][org.springframework.beans.factory.support.DefaultListableBeanFactory] Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@66b4c2e4: defining beans [org.springframework.integration.internalDefaultConfiguringBeanFactoryPostProcessor,/receiveGateway,receiveChannel,org.springframework.integration.config.ServiceActivatorFactoryBean#0,org.springframework.integration.config.ConsumerEndpointFactoryBean#0,nullChannel,errorChannel,_org.springframework.integration.errorLogger,taskScheduler,org.springframework.integration.config.IdGeneratorConfigurer#0]; root of factory hierarchy
15:15:40.455 INFO [main][org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler] Initializing ExecutorService 'taskScheduler'
15:15:40.461 INFO [main][org.springframework.context.support.DefaultLifecycleProcessor] Starting beans in phase -2147483648
15:15:40.462 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] Adding {service-activator} as a subscriber to the 'receiveChannel' channel
15:15:40.462 INFO [main][org.springframework.integration.channel.DirectChannel] Channel 'receiveChannel' has 1 subscriber(s).
15:15:40.462 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] started org.springframework.integration.config.ConsumerEndpointFactoryBean#0
15:15:40.462 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] Adding {logging-channel-adapter:_org.springframework.integration.errorLogger} as a subscriber to the 'errorChannel' channel
15:15:40.462 INFO [main][org.springframework.integration.channel.PublishSubscribeChannel] Channel 'errorChannel' has 1 subscriber(s).
15:15:40.462 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] started _org.springframework.integration.errorLogger
15:15:40.462 INFO [main][org.springframework.context.support.DefaultLifecycleProcessor] Starting beans in phase 0
15:15:40.463 INFO [main][org.springframework.integration.http.inbound.HttpRequestHandlingMessagingGateway] started /receiveGateway
15:15:40.500 INFO [main][org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping] Mapped URL path [/receiveGateway] onto handler '/receiveGateway'
15:15:40.766 INFO [main][org.springframework.web.servlet.DispatcherServlet] FrameworkServlet 'Multipart': initialization completed in 1962 ms
2012-10-25 15:15:40.169::INFO: Started [email protected]:8080[INFO] Started Jetty Server

客户端代码

看HttpClientDemo.java

	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("/META-INF/spring/integration/http-outbound-config.xml");
		RequestGateway requestGateway = context.getBean("requestGateway", RequestGateway.class);
		String reply = requestGateway.echo("Hello");  
		logger.info("Replied with: " + reply);
	}

其中一个main函数，里面创建一个spring 的context,使用配置文件为META-INF/spring/integration/http-outbound-config.xml

创建一个requestGateway，调用它的一个echo方法，然后得到结果，并输出，也非常简单。

下面我们看一下RequestGateway.java

package org.springframework.integration.samples.http;


/**
 * @author Oleg Zhurakousky
 *
 */
public interface RequestGateway {

	public String echo(String request);
}

这是一个接口，只有一个echo的方法声明，其他什么也没有了，那么调用这个方法的时候信息发哪了？

只能看看/http-outbound-config.xml配置了

	<int:gateway id="requestGateway" 
	             service-interface="org.springframework.integration.samples.http.RequestGateway"
	             default-request-channel="requestChannel"/>
	
	<int:channel id="requestChannel"/>

	<int-http:outbound-gateway request-channel="requestChannel" 
					           url="http://localhost:8080/http/receiveGateway"
					           http-method="POST"
					           expected-response-type="java.lang.String"/>

配置了一个gateway,关联上RequestGateway，并关联一个通道requestChannel，将信息关联到一个outbound-gateway，将信息以POST形式发送到http://localhost:8080/http/receiveGateway地址，正好服务端就可以接受了。

右键run as -->java application，就可以运行了。

可以从输出信息中查看到结果。

15:17:07.013 INFO [main][org.springframework.context.support.ClassPathXmlApplicationContext] Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@25a268f2: startup date [Thu Oct 25 15:17:06 CST 2012]; root of context hierarchy
15:17:07.097 INFO [main][org.springframework.beans.factory.xml.XmlBeanDefinitionReader] Loading XML bean definitions from class path resource [META-INF/spring/integration/http-outbound-config.xml]
15:17:07.700 INFO [main][org.springframework.integration.config.xml.DefaultConfiguringBeanFactoryPostProcessor] No bean named 'errorChannel' has been explicitly defined. Therefore, a default PublishSubscribeChannel will be created.
15:17:07.700 INFO [main][org.springframework.integration.config.xml.DefaultConfiguringBeanFactoryPostProcessor] No bean named 'taskScheduler' has been explicitly defined. Therefore, a default ThreadPoolTaskScheduler will be created.
15:17:07.715 INFO [main][org.springframework.beans.factory.support.DefaultListableBeanFactory] Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@7fee6f88: defining beans [org.springframework.integration.internalDefaultConfiguringBeanFactoryPostProcessor,requestGateway,requestChannel,org.springframework.integration.http.outbound.HttpRequestExecutingMessageHandler#0,org.springframework.integration.config.ConsumerEndpointFactoryBean#0,nullChannel,errorChannel,_org.springframework.integration.errorLogger,taskScheduler,org.springframework.integration.config.IdGeneratorConfigurer#0]; root of factory hierarchy
15:17:07.934 INFO [main][org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler] Initializing ExecutorService 'taskScheduler'
15:17:07.988 INFO [main][org.springframework.integration.gateway.GatewayProxyFactoryBean$MethodInvocationGateway] started requestGateway
15:17:07.988 INFO [main][org.springframework.integration.gateway.GatewayProxyFactoryBean] started requestGateway
15:17:08.419 INFO [main][org.springframework.context.support.DefaultLifecycleProcessor] Starting beans in phase -2147483648
15:17:08.419 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] Adding {message-handler} as a subscriber to the 'requestChannel' channel
15:17:08.419 INFO [main][org.springframework.integration.channel.DirectChannel] Channel 'requestChannel' has 1 subscriber(s).
15:17:08.420 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] started org.springframework.integration.config.ConsumerEndpointFactoryBean#0
15:17:08.420 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] Adding {logging-channel-adapter:_org.springframework.integration.errorLogger} as a subscriber to the 'errorChannel' channel
15:17:08.420 INFO [main][org.springframework.integration.channel.PublishSubscribeChannel] Channel 'errorChannel' has 1 subscriber(s).
15:17:08.420 INFO [main][org.springframework.integration.endpoint.EventDrivenConsumer] started _org.springframework.integration.errorLogger
15:17:08.420 INFO [main][org.springframework.context.support.DefaultLifecycleProcessor] Starting beans in phase 0
15:17:08.799 INFO [main][org.springframework.integration.samples.http.HttpClientDemo] Replied with: Hello from the other side

总结

服务器端组件如下：

http inbound gateway 就是用来通过HTTP获取信息的,而service-activator通常是处理信息的服务。

客户端组件关系：

outboundgateway则是用于向外发送数据，通过这个例子可以很好的理解这两个gateway 的作用。