一. 开篇语
今天很坑爹啊, 为了搞一下JMS这个玩意, 整了一天了, 光是weblogic的环境就换了两, 最后总算是搞定了, 写下这篇日志, 记录下学习的心得.
二. JMS的思想
所谓的JMS其实就是异步通信, 我们可以打个简单的比方: 现在的手机基本上普及了, 手机它有两个基本功能, 一个是打电话, 一个是发短信.
打电话是同步的, 必须要保证双方都开机才能进行通话; 而发短信则是异步的, 接收方不需要保持开机状态;
SUN公司给我们提供了一组标准被Java API用于企业级的消息处理, 通过JMS可以在Java程序之间发送和接受消息以达到交换数据的目的,
异步通信实现了程序之间的松耦合的关系.
三. 名词解释
1. 连接工厂(ConnectionFactory): 用来创建消息服务器的connection对象.
2. 连接(Connection): 代表一个与JMS提供者的活动连接.
3. 目的(Destination): 标识消息的发送和接收方式, 分为队列(Queue)和主题(Topic)两种.
4. 会话(Session): 接收和发送消息的会话线程.
5. 为了实现JMS独立于不同供应商MS的专有技术, weblogic JMS采用了受管对象(administratored object)的机制. 受管对象就是由消息服务器通过管理界面创建, 程序通过JNDI接口取得这些对象.weblogic 中的两种受管对象: connection factory, distination.
四. 消息类型
1. StreamMessage: 消息由串行化的Java对象组成, 必须按照设置时的顺序读取对象.
2. MapMessage: 消息由key/value对组成, 其中名称为string类型, 值为Java数据类型. 可以使用列举顺序读取该消息的值, 也可以通过名称无序地获取值。
3. TextMessage: 消息的主体为字符串, 这是最常用的消息类型.
4. ObjectMessage: 消息的主体为串行化的Java对象, 可以是自己定义的串行化的Java对象.
5. BytesMessage: 消息的主体是二进制数据.
五. 环境准备
1. myeclipse环境
① jre1.4
② j2ee 1.4 libraries
③ 导入weblogic.jar
2. weblogic环境
① 安装weblogic8.1并集成到myeclipse
http://blog.youkuaiyun.com/zdp072/article/details/26831739
② 配置weblogic服务器
1)、新建jms连接工厂，工厂名称为“myJMSConnectionFactory”, JNDI name为"myJMSConnectionFactoryJNDIName" .
2)、定义后备存储, 并填写存储目录.
3)、新建jms服务器，服务器名称为：“myJMSServer”.
4)、在“myJMSServer”服务下新建目标为“myJMSQueue”队列, JNDI name为"myJMSQueueJNDIName".
5)、在“myJMSServer”服务下新建目标为“myJMSTopic”主题, JNDI name为"myJMSTopicJNDIName".
六. 代码实现
1. PTP(point to point) - 点对点模式.
生产者发送一条消息到消息服务器, 消息服务器发送给一个消费者, 这条消息不能再发送给其他消费者, 相当于队列, 先到先得.
(一个消息生产者对应一个消息消费者)
①. 实体类User
/**
* 实体类
* @author zhangjim
*/
public class User implements Serializable {
private static final long serialVersionUID = 1L;
private String name;
private int age;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
②. 生产者QueueMsgSender
public class QueueMsgSender {
// Defines the JNDI context factory.
public final static String JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory";
// Defines the JNDI provider url.
public final static String PROVIDER_URL = "t3://localhost:7001/";
// Defines the JMS connection factory for the queue.
public final static String CONNECTION_FACTORY_JNDI_NAME = "myJMSConnectionFactoryJNDIName";
// Defines the queue, use the queue JNDI name
public final static String QUEUE_JNDI_NAME = "myJMSQueueJNDIName";
private QueueConnectionFactory qconFactory;
private QueueConnection queueConnection;
private QueueSession queueSession;
private QueueSender queueSender;
private Queue queue;
private TextMessage textMessage;
private StreamMessage streamMessage;
private BytesMessage bytesMessage;
private MapMessage mapMessage;
private ObjectMessage objectMessage;
/**
* get the context object.
*
* @return context object
* @throws NamingException if operation cannot be performed
*/
private static InitialContext getInitialContext() throws NamingException {
Hashtable table = new Hashtable();
table.put(Context.INITIAL_CONTEXT_FACTORY, JNDI_FACTORY);
table.put(Context.PROVIDER_URL, PROVIDER_URL);
InitialContext context = new InitialContext(table);
return context;
}
/**
* Creates all the necessary objects for sending messages to a JMS queue.
*
* @param ctx JNDI initial context
* @param queueName name of queue
* @exception NamingException if operation cannot be performed
* @exception JMSException if JMS fails to initialize due to internal error
*/
public void init(Context ctx, String queueName) throws NamingException, JMSException {
qconFactory = (QueueConnectionFactory) ctx.lookup(CONNECTION_FACTORY_JNDI_NAME);
queueConnection = qconFactory.createQueueConnection();
queueSession = queueConnection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
queue = (Queue) ctx.lookup(queueName);
queueSender = queueSession.createSender(queue);
textMessage = queueSession.createTextMessage();
streamMessage = queueSession.createStreamMessage();
bytesMessage = queueSession.createBytesMessage();
mapMessage = queueSession.createMapMessage();
objectMessage = queueSession.createObjectMessage();
queueConnection.start();
}
/**
* Sends a message to a JMS queue.
*
* @param message message to be sent
* @exception JMSException if JMS fails to send message due to internal error
*/
public void send(String message) throws JMSException {
// type1: set TextMessage
textMessage.setText(message);
// type2: set StreamMessage
streamMessage.writeString(message);
streamMessage.writeInt(20);
// type3: set BytesMessage
byte[] block = message.getBytes();
bytesMessage.writeBytes(block);
// type4: set MapMessage
mapMessage.setString("name", message);
// type5: set ObjectMessage
User user = new User();
user.setName(message);
user.setAge(30);
objectMessage.setObject(user);
queueSender.send(objectMessage);
}
/**
* read the msg from the console, then send it.
*
* @param msgSender
* @throws IOException if IO fails to send message due to internal error
* @throws JMSException if JMS fails to send message due to internal error
*/
private static void readAndSend(QueueMsgSender msgSender) throws IOException, JMSException {
BufferedReader msgStream = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter message(input quit to quit):");
String line = null;
boolean quit = false;
do {
line = msgStream.readLine();
if (line != null && line.trim().length() != 0) {
msgSender.send(line);
System.out.println("JMS Message Sent: " + line + "\n");
quit = line.equalsIgnoreCase("quit");
}
} while (!quit);
}
/**
* release resources.
*
* @exception JMSException if JMS fails to close objects due to internal error
*/
public void close() throws JMSException {
queueSender.close();
queueSession.close();
queueConnection.close();
}
/**
* test client.
*
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
InitialContext ctx = getInitialContext();
QueueMsgSender sender = new QueueMsgSender();
sender.init(ctx, QUEUE_JNDI_NAME);
readAndSend(sender);
sender.close();
}
}
③. 消费者QueueMsgReceiver
public class QueueMsgReceiver implements MessageListener {
// Defines the JNDI context factory.
public final static String JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory";
// Defines the JNDI provider url.
public final static String PROVIDER_URL = "t3://localhost:7001";
// Defines the JMS connection factory for the queue.
public final static String CONNECTION_FACTORY_JNDI_NAME = "myJMSConnectionFactoryJNDIName";
// Defines the queue, use the queue JNDI name
public final static String QUEUE_JNDI_NAME = "myJMSQueueJNDIName";
private QueueConnectionFactory qconFactory;
private QueueConnection queueConnection;
private QueueSession queueSession;
private QueueReceiver queueReceiver;
private Queue queue;
private boolean quit = false;
/**
* get the context object.
*
* @return context object
* @throws NamingException if operation cannot be performed
*/
private static InitialContext getInitialContext() throws NamingException {
Hashtable table = new Hashtable();
table.put(Context.INITIAL_CONTEXT_FACTORY, JNDI_FACTORY);
table.put(Context.PROVIDER_URL, PROVIDER_URL);
InitialContext context = new InitialContext(table);
return context;
}
/**
* Creates all the necessary objects for receiving messages from a JMS queue.
*
* @param ctx JNDI initial context
* @param queueName name of queue
* @exception NamingException if operation cannot be performed
* @exception JMSException if JMS fails to initialize due to internal error
*/
public void init(Context ctx, String queueName) throws NamingException, JMSException {
qconFactory = (QueueConnectionFactory) ctx.lookup(CONNECTION_FACTORY_JNDI_NAME);
queueConnection = qconFactory.createQueueConnection();
queueSession = queueConnection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
queue = (Queue) ctx.lookup(queueName);
queueReceiver = queueSession.createReceiver(queue);
queueReceiver.setMessageListener(this);
// second thread: message reveive thread.
queueConnection.start();
}
/**
* implement from MessageListener.
* when a message arrived, it will be invoked.
*
* @param message message
*/
public void onMessage(Message message) {
try {
String msgStr = "";
int age = 0;
if (message instanceof TextMessage) {
msgStr = ((TextMessage) message).getText();
} else if (message instanceof StreamMessage) {
msgStr = ((StreamMessage) message).readString();
age = ((StreamMessage) message).readInt();
} else if (message instanceof BytesMessage) {
byte[] block = new byte[1024];
((BytesMessage) message).readBytes(block);
msgStr = String.valueOf(block);
} else if (message instanceof MapMessage) {
msgStr = ((MapMessage) message).getString("name");
} else if (message instanceof ObjectMessage) {
User user = (User) ((ObjectMessage) message).getObject();
msgStr = user.getName();
age = user.getAge();
}
System.out.println("Message Received: " + msgStr + ", " + age);
if (msgStr.equalsIgnoreCase("quit")) {
synchronized (this) {
quit = true;
this.notifyAll(); // Notify main thread to quit
}
}
} catch (JMSException e) {
throw new RuntimeException("error happens", e);
}
}
/**
* release resources.
*
* @exception JMSException if JMS fails to close objects due to internal error
*/
public void close() throws JMSException {
queueReceiver.close();
queueSession.close();
queueConnection.close();
}
/**
* test client.
* first thread(main thread)
*
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
InitialContext ctx = getInitialContext();
QueueMsgReceiver receiver = new QueueMsgReceiver();
receiver.init(ctx, QUEUE_JNDI_NAME);
// Wait until a "quit" message has been received.
synchronized (receiver) {
while (!receiver.quit) {
try {
receiver.wait();
} catch (InterruptedException e) {
throw new RuntimeException("error happens", e);
}
}
}
receiver.close();
}
}
2. publisher and subscriber - 发布订阅模式.
生产者发送一条消息到消息服务器, 消息服务器发送给正在监听的所有消费者, 类似广播.
(一个消息生产者对应多个消息消费者)
①. 生产者TopicMsgPublisher
public class TopicMsgPublisher {
// Defines the JNDI context factory.
public final static String JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory";
// Defines the JNDI provider url.
public final static String PROVIDER_URL = "t3://localhost:7001/";
// Defines the JMS connection factory for the topic.
public final static String CONNECTION_FACTORY_JNDI_NAME = "myJMSConnectionFactoryJNDIName";
// Defines the topic, use the topic JNDI name
public final static String TOPIC_JNDI_NAME = "myJMSTopicJNDIName";
private TopicConnectionFactory tconFactory;
private TopicConnection topicConnection;
private TopicSession topicSession;
private TopicPublisher topicPublisher;
private Topic topic;
private TextMessage textMessage;
private StreamMessage streamMessage;
private BytesMessage bytesMessage;
private MapMessage mapMessage;
private ObjectMessage objectMessage;
/**
* get the context object.
*
* @return context object
* @throws NamingException if operation cannot be performed
*/
private static InitialContext getInitialContext() throws NamingException {
Hashtable table = new Hashtable();
table.put(Context.INITIAL_CONTEXT_FACTORY, JNDI_FACTORY);
table.put(Context.PROVIDER_URL, PROVIDER_URL);
InitialContext context = new InitialContext(table);
return context;
}
/**
* Creates all the necessary objects for sending messages to a JMS topic.
*
* @param ctx JNDI initial context
* @param topicName name of topic
* @exception NamingException if operation cannot be performed
* @exception JMSException if JMS fails to initialize due to internal error
*/
public void init(Context ctx, String topicName) throws NamingException, JMSException {
tconFactory = (TopicConnectionFactory) ctx.lookup(CONNECTION_FACTORY_JNDI_NAME);
topicConnection = tconFactory.createTopicConnection();
topicSession = topicConnection.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);
topic = (Topic) ctx.lookup(topicName);
topicPublisher = topicSession.createPublisher(topic);
textMessage = topicSession.createTextMessage();
streamMessage = topicSession.createStreamMessage();
bytesMessage = topicSession.createBytesMessage();
mapMessage = topicSession.createMapMessage();
objectMessage = topicSession.createObjectMessage();
topicConnection.start();
}
/**
* Sends a message to a JMS topic.
*
* @param message message to be sent
* @exception JMSException if JMS fails to send message due to internal error
*/
public void send(String message) throws JMSException {
// type1: set TextMessage
textMessage.setText(message);
// type2: set StreamMessage
streamMessage.writeString(message);
streamMessage.writeInt(20);
// type3: set BytesMessage
byte[] block = message.getBytes();
bytesMessage.writeBytes(block);
// type4: set MapMessage
mapMessage.setString("name", message);
// type5: set ObjectMessage
User user = new User();
user.setName(message);
user.setAge(30);
objectMessage.setObject(user);
topicPublisher.publish(objectMessage);
}
/**
* read the msg from the console, then send it.
*
* @param msgPublisher
* @throws IOException if IO fails to send message due to internal error
* @throws JMSException if JMS fails to send message due to internal error
*/
private static void readAndSend(TopicMsgPublisher msgPublisher) throws IOException, JMSException {
BufferedReader msgStream = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter message(input quit to quit):");
String line = null;
boolean quit = false;
do {
line = msgStream.readLine();
if (line != null && line.trim().length() != 0) {
msgPublisher.send(line);
System.out.println("JMS Message Sent: " + line + "\n");
quit = line.equalsIgnoreCase("quit");
}
} while (!quit);
}
/**
* release resources.
*
* @exception JMSException if JMS fails to close objects due to internal error
*/
public void close() throws JMSException {
topicPublisher.close();
topicSession.close();
topicConnection.close();
}
/**
* test client.
*
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
InitialContext ctx = getInitialContext();
TopicMsgPublisher publisher = new TopicMsgPublisher();
publisher.init(ctx, TOPIC_JNDI_NAME);
readAndSend(publisher);
publisher.close();
}
}
②. 消费者TopicMsgSubscriber
public class TopicMsgSubscriber implements MessageListener {
// Defines the JNDI context factory.
public final static String JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory";
// Defines the JNDI provider url.
public final static String PROVIDER_URL = "t3://localhost:7001";
// Defines the JMS connection factory for the topic.
public final static String CONNECTION_FACTORY_JNDI_NAME = "myJMSConnectionFactoryJNDIName";
// Defines the topic, use the topic JNDI name
public final static String TOPIC_JNDI_NAME = "myJMSTopicJNDIName";
private TopicConnectionFactory tconFactory;
private TopicConnection topicConnection;
private TopicSession topicSession;
private TopicSubscriber topicSubscriber;
private Topic topic;
private boolean quit = false;
/**
* get the context object.
*
* @return context object
* @throws NamingException if operation cannot be performed
*/
private static InitialContext getInitialContext() throws NamingException {
Hashtable table = new Hashtable();
table.put(Context.INITIAL_CONTEXT_FACTORY, JNDI_FACTORY);
table.put(Context.PROVIDER_URL, PROVIDER_URL);
InitialContext context = new InitialContext(table);
return context;
}
/**
* Creates all the necessary objects for receiving messages from a JMS topic.
*
* @param ctx JNDI initial context
* @param topicName name of topic
* @exception NamingException if operation cannot be performed
* @exception JMSException if JMS fails to initialize due to internal error
*/
public void init(Context ctx, String topicName) throws NamingException, JMSException {
tconFactory = (TopicConnectionFactory) ctx.lookup(CONNECTION_FACTORY_JNDI_NAME);
topicConnection = tconFactory.createTopicConnection();
topicSession = topicConnection.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);
topic = (Topic) ctx.lookup(topicName);
topicSubscriber = topicSession.createSubscriber(topic);
topicSubscriber.setMessageListener(this);
// second thread: message reveive thread.
topicConnection.start();
}
/**
* implement from MessageListener.
* when a message arrived, it will be invoked.
*
* @param message message
*/
public void onMessage(Message message) {
try {
String msgStr = "";
int age = 0;
if (message instanceof TextMessage) {
msgStr = ((TextMessage) message).getText();
} else if (message instanceof StreamMessage) {
msgStr = ((StreamMessage) message).readString();
age = ((StreamMessage) message).readInt();
} else if (message instanceof BytesMessage) {
byte[] block = new byte[1024];
((BytesMessage) message).readBytes(block);
msgStr = String.valueOf(block);
} else if (message instanceof MapMessage) {
msgStr = ((MapMessage) message).getString("name");
} else if (message instanceof ObjectMessage) {
User user = (User) ((ObjectMessage) message).getObject();
msgStr = user.getName();
age = user.getAge();
}
System.out.println("Message subscribed: " + msgStr + ", " + age);
if (msgStr.equalsIgnoreCase("quit")) {
synchronized (this) {
quit = true;
this.notifyAll(); // Notify main thread to quit
}
}
} catch (JMSException e) {
throw new RuntimeException("error happens", e);
}
}
/**
* release resources.
*
* @exception JMSException if JMS fails to close objects due to internal error
*/
public void close() throws JMSException {
topicSubscriber.close();
topicSession.close();
topicConnection.close();
}
/**
* test client.
* first thread(main thread)
*
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
InitialContext ctx = getInitialContext();
TopicMsgSubscriber subscriber = new TopicMsgSubscriber();
subscriber.init(ctx, TOPIC_JNDI_NAME);
// Wait until a "quit" message has been subscribed.
synchronized (subscriber) {
while (!subscriber.quit) {
try {
subscriber.wait();
} catch (InterruptedException e) {
throw new RuntimeException("error happens", e);
}
}
}
subscriber.close();
}
}
七. 总结
使用JMS可以把不影响用户执行结果又比较耗时的任务异步的扔给JMS服务器端, 而尽快地把屏幕还给用户, 且服务器端能够多线程排队相应高并发的请求, 在Java世界里达到最高境界的解耦. 客户端和服务器端无须直连, 甚至无需知道对方是谁、在哪里、有多少人, 只要对流过的信息作响应就行了, 在企业应用复杂时作用非常明显.
八. 源码下载
下载源码请点击此链接: http://download.youkuaiyun.com/detail/zdp072/7422431
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