JMS规范中五种消息类型
摘要: 本文讲述了JMS规范中五种消息类型，包括TextMessage、BytesMessage、MapMessage、StreamMessage和ObjectMessage
1.前言ActiveMQ学习笔记(四)——通过ActiveMQ收发消息http://my.oschina.net/xiaoxishan/blog/380446和ActiveMQ学习笔记(五)——使用Spring JMS收发消息http://my.oschina.net/xiaoxishan/blog/381209中，发送和接受的消息类型都是TextMessage，即文本消息（如下面的代码所示）。显然消息类型只有文本类型是不能满足要求的。
//发送文本消息
session.createTextMessage(msg);
//接受文本消息
publicvoidonMessage(Messagemsg){
TextMessagemessage=(TextMessage)msg;
……
}
根据Message接口的方法，可以获取消息类型
StringmsgType=getJMSType()
根据JSR 914: JavaTM Message Service (JMS) API，JMS规范中的消息类型包括TextMessage、BytesMessage、MapMessage、StreamMessage和ObjectMessage等五种。ActiveMQ也有对应的实现，下面我们结合Spring JMS分别来看一下五种消息类型的收发代码。
2. 消息发送示例代码/**
*向默认队列发送text消息
*/
publicvoidsendMessage(finalStringmsg){
Stringdestination=jmsTemplate.getDefaultDestination().toString();
System.out.println("ProducerService向队列"+destination+"发送了消息：\t"+msg);
jmsTemplate.send(newMessageCreator(){
publicMessagecreateMessage(Sessionsession)throwsJMSException{
returnsession.createTextMessage(msg);
}
});
}
/**
*向默认队列发送map消息
*/
publicvoidsendMapMessage(){
jmsTemplate.send(newMessageCreator(){
publicMessagecreateMessage(Sessionsession)throwsJMSException{
MapMessagemessage=session.createMapMessage();
message.setString("name","小西山");
returnmessage;
}
});
}
/**
*向默认队列发送Object消息
*/
publicvoidsendObjectMessage(){
jmsTemplate.send(newMessageCreator(){
publicMessagecreateMessage(Sessionsession)throwsJMSException{
Staffstaff=newStaff(1,"搬砖工");//Staff必须实现序列化
ObjectMessagemessage=session.createObjectMessage(staff);
returnmessage;
}
});
}
/**
*向默认队列发送Bytes消息
*/
publicvoidsendBytesMessage(){
jmsTemplate.send(newMessageCreator(){
publicMessagecreateMessage(Sessionsession)throwsJMSException{
Stringstr="BytesMessage字节消息";
BytesMessagemessage=session.createBytesMessage();
message.writeBytes(str.getBytes());
returnmessage;
}
});
}
/**
*向默认队列发送Stream消息
*/
publicvoidsendStreamMessage(){
jmsTemplate.send(newMessageCreator(){
publicMessagecreateMessage(Sessionsession)throwsJMSException{
Stringstr="StreamMessage流消息";
StreamMessagemessage=session.createStreamMessage();
message.writeString(str);
message.writeInt(521);
returnmessage;
}
});
}
3.消息接受示例代码/**
*接受消息
*/
publicvoidreceive(Destinationdestination)throwsJMSException{
Messagemessage=jmsTemplate.receive(destination);
//如果是文本消息
if(messageinstanceofTextMessage){
TextMessagetm=(TextMessage)message;
System.out.println("ConsumerService从队列"+destination.toString()+"收到了消息：\t"+tm.getText());
}
//如果是Map消息
if(messageinstanceofMapMessage){
MapMessagemm=(MapMessage)message;
System.out.println("ConsumerService从队列"+destination.toString()+"收到了消息：\t"
+mm.getString("name"));
}
//如果是Object消息
if(messageinstanceofObjectMessage){
ObjectMessageom=(ObjectMessage)message;
Staffstaff=(Staff)om.getObject();
System.out.println("ConsumerService从队列"+destination.toString()+"收到了消息：\t"+staff);
}
//如果是bytes消息
if(messageinstanceofBytesMessage){
byte[]b=newbyte[1024];
intlen=-1;
BytesMessagebm=(BytesMessage)message;
while((len=bm.readBytes(b))!=-1){
System.out.println(newString(b,0,len));
}
}
//如果是Stream消息
if(messageinstanceofStreamMessage){
StreamMessagesm=(StreamMessage)message;
System.out.println(sm.readString());
System.out.println(sm.readInt());
}
}
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