Camel自定义组件示例

最新推荐文章于 2022-02-23 10:29:37 发布

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最新推荐文章于 2022-02-23 10:29:37 发布

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分类专栏： camel 文章标签： camel component

本文链接：https://blog.youkuaiyun.com/xtayfjpk/article/details/39122349

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本文提供了一个使用Camel自定义组件的实例，重点介绍如何创建一个以文件轮询为基础的组件。详细展示了组件类的实现代码，帮助理解Camel自定义组件的开发过程。

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要想在Camel中自定义组件，就要对Camel中关键概念进行理解，了解Camel中路由的构建过程与启动过程，在前面的文章中已经有相关的叙述。

这里就给出一个自定义组件的例子。该例子还是以文件轮询为主题，下面是具体代码。

组件类：

package com.xtayfjpk.esb.components.file;

import java.util.Map;

import org.apache.camel.Endpoint;
import org.apache.camel.impl.DefaultComponent;

public class MyFileComponent extends DefaultComponent {

	@Override
	protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
		return new MyFileEndpoint(this, uri);
	}

}

Endpoint类：

package com.xtayfjpk.esb.components.file;

import java.io.File;

import org.apache.camel.Consumer;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.Producer;
import org.apache.camel.component.file.FileComponent;
import org.apache.camel.impl.DefaultEndpoint;
import org.apache.camel.impl.DefaultExchange;

public class MyFileEndpoint extends DefaultEndpoint {

	public MyFileEndpoint(MyFileComponent component, String uri) {
		super(uri, component);
	}

	@Override
	public Producer createProducer() throws Exception {
		return new MyFileProducer(this);
	}

	@Override
	public Consumer createConsumer(Processor processor) throws Exception {
		return new MyFileConsumer(this, processor);
	}

	@Override
	public boolean isSingleton() {
		return false;
	}
	
	public Exchange createExchange(File file) {
		Exchange exchange = new DefaultExchange(getCamelContext());
		exchange.setProperty(FileComponent.FILE_EXCHANGE_FILE, file);
		exchange.getIn().setBody(file, File.class);
		return exchange;
	}
}

Consumer类：

package com.xtayfjpk.esb.components.file;

import java.io.File;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.impl.DefaultConsumer;

public class MyFileConsumer extends DefaultConsumer implements Runnable {
	private ScheduledExecutorService executorService = Executors.newScheduledThreadPool(1);
	private File pollDir;
	
	public MyFileConsumer(Endpoint endpoint, Processor processor) {
		super(endpoint, processor);
		
		String pollDir = endpoint.getEndpointUri().substring(endpoint.getEndpointUri().indexOf(":")+1);
		this.pollDir = new File(pollDir);
	}
	
	
	@Override
	protected void doStart() throws Exception {
		super.doStart();
		
		executorService.scheduleAtFixedRate(this, 1000L, 1000L, TimeUnit.MILLISECONDS);
		
	}


	@Override
	public void run() {
		File[] files = pollDir.listFiles();
		for(File file : files) {
			MyFileEndpoint endpoint = (MyFileEndpoint) getEndpoint();
			Exchange exchange = endpoint.createExchange(file);
			try {
				processExchange(exchange);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		
	}


	private void processExchange(Exchange exchange) throws Exception {
		this.getProcessor().process(exchange);
	}

}

Producer类：

package com.xtayfjpk.esb.components.file;

import java.io.File;

import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.impl.DefaultProducer;
import org.apache.commons.io.FileUtils;

public class MyFileProducer extends DefaultProducer {
	private File outputDir;

	public MyFileProducer(Endpoint endpoint) {
		super(endpoint);
		
		this.outputDir = new File(endpoint.getEndpointUri().substring(endpoint.getEndpointUri().indexOf(":")+1));
	}

	@Override
	public void process(Exchange exchange) throws Exception {
		File file = exchange.getIn().getBody(File.class);
		if(file!=null) {
			FileUtils.moveFileToDirectory(file, outputDir, true);
		}
	}

}

测试类：

package com.xtayfjpk.esb.components.file;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;

import org.apache.camel.CamelContext;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.impl.DefaultCamelContext;

public class MyComponentTest {

	/**
	 * @param args
	 * @throws Exception 
	 */
	public static void main(String[] args) throws Exception {
		CamelContext camelContext = new DefaultCamelContext();
		//为了简单起见，用该方法替代了在类路径META-INF/services/org/apache/camel/component/下放置properties文件方式
		camelContext.addComponent("myfile", new MyFileComponent());

		camelContext.addRoutes(new RouteBuilder() {
			
			@Override
			public void configure() throws Exception {
				this.from("myfile:H:/temp/in").process(new Processor() {
					@Override
					public void process(Exchange exchange) throws Exception {
						File file = exchange.getIn().getBody(File.class);
						PrintStream ps = new PrintStream(System.out);
						BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
						String line = null;
						while((line=br.readLine())!=null) {
							ps.println(line);
						}
						
						ps.close();
						br.close();
					}
				}).to("myfile:H:/temp/out");
				
			}
		});
		
		camelContext.start();
		
		Object object = new Object();
		synchronized (object) {
			object.wait();
		}
	}

}

如果一个组件是一个起始组件，或称为源组件，那么对应的Endpoint就必须要能创建出一个Consumer对象，如果这个组件还想是目的组件，那么对应的Endpoint还必须能创建出Producer对象。Consumer负责Exchange对象的产生，而Producer负责将Exchange对象中的消费。当然在真实应该中组件不可能写得如此简单，但大致流程是一样的，在这个例子中已经能够简单实现轮询出组件并搬运至指定目录了。