Posted on 2011-08-28 23:40
匆匆过客 阅读(5271)
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Java
这个方法还有待研究，目前还有如下几个疑点：1. ActiveMQ 报出这样的信息：
INFO | Usage Manager memory limit (1048576) reached for topic://EXCHANGE.FILE. Producers will be throttled to the rate at which messages are removed from this
destination to prevent flooding it. See http://activemq.apache.org/producer-flow-control.html for more info2. 这种以异步方式传送资料，能保证客户端能以正确的顺序接收到文件段麽？
使用ActiveMQ传送文件，发送端必须将文件拆成一段一段，每段封装在独立的Message中，逐次发送到客户端。例如下面的例子，Producer通过发送命令，告诉文件传送的开始，发送中，结束。客户端接收到这些命令之后，就知道如何接收资料了。
客户端收到内容后，根据命令将内容合并到一个文件中。
package org.apache.activemq.exchange.file;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.Session;
import javax.jms.StreamMessage;
import org.apache.activemq.ActiveMQConnectionFactory;
public class Consumer {
/**
* @param args
*/
public static void main(String[] args) throws JMSException, IOException {
ConnectionFactory factory = new ActiveMQConnectionFactory("tcp://localhost:61616");
Connection connection = factory.createConnection();
connection.start();
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
Destination destination = session.createTopic("EXCHANGE.FILE");
MessageConsumer consumer = session.createConsumer(destination);
boolean appended = false;
try {
while (true) {
Message message = consumer.receive(5000);
if (message == null) {
continue;
}
if (message instanceof StreamMessage) {
StreamMessage streamMessage = (StreamMessage) message;
String command = streamMessage.getStringProperty("COMMAND");
if ("start".equals(command)) {
appended = false;
continue;
}
if ("sending".equals(command)) {
byte[] content = new byte[4096];
String file_name = message.getStringProperty("FILE_NAME");
BufferedOutputStream bos = null;
bos = new BufferedOutputStream(new FileOutputStream("c:/" + file_name, appended));
if (!appended) {
appended = true;
}
while (streamMessage.readBytes(content) > 0) {
bos.write(content);
}
bos.close();
continue;
}
if ("end".equals(command)) {
appended = false;
continue;
}
}
}
} catch (JMSException e) {
throw e;
} finally {
if (connection != null) {
connection.close();
}
}
}
}
发送端将文件分包，逐次发送到客户端
package org.apache.activemq.exchange.file;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.StreamMessage;
import org.apache.activemq.ActiveMQConnectionFactory;
public class Publisher {
public static String FILE_NAME = "01.mp3";
public static void main(String[] args) throws JMSException, IOException {
ConnectionFactory factory = new ActiveMQConnectionFactory("tcp://localhost:61616");
Connection connection = factory.createConnection();
connection.start();
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
Destination destination = session.createTopic("EXCHANGE.FILE");
MessageProducer producer = session.createProducer(destination);
long time = System.currentTimeMillis();
//通知客户端开始接受文件
StreamMessage message = session.createStreamMessage();
message.setStringProperty("COMMAND", "start");
producer.send(message);
//开始发送文件
byte[] content = new byte[4096];
InputStream ins = Publisher.class.getResourceAsStream(FILE_NAME);
BufferedInputStream bins = new BufferedInputStream(ins);
while (bins.read(content) > 0) {
//
message = session.createStreamMessage();
message.setStringProperty("FILE_NAME", FILE_NAME);
message.setStringProperty("COMMAND", "sending");
message.clearBody();
message.writeBytes(content);
producer.send(message);
}
bins.close();
ins.close();
//通知客户端发送完毕
message = session.createStreamMessage();
message.setStringProperty("COMMAND", "end");
producer.send(message);
connection.close();
System.out.println("Total Time costed : " + (System.currentTimeMillis() - time) + " mili seconds");
}
}