Sample code sharing of message queue in Java

This article mainly introduces the simple implementation code of Java message queue. The editor thinks it is quite good. Now I will share it with you and give you a reference. Let’s follow the editor and take a look.

Today I saw that our recruitment information has requirements for message queues, and then I thought about it and searched a lot online.

I can give a small example to illustrate the application scenario

Assume that your server has a processing capacity of 200 per minute. But when the client peaks again, it may send 1,000 messages to you a minute. At this time, you can make it into a queue, and then process it in a normal order, first in last out (LIFO), first in first out (FIFO) You can make a decision based on your own situation

stack First in last out (LIFO)--------Java's corresponding class Stack

queue first in first out (LIFO) FIFO)--------java corresponding class Queue

Both of these can be encapsulated and implemented by Linkedlist. The following is an example of a stack I wrote myself

/** 
 * @author 刘伊凡 
 * --------->>>>>>队列的实现-------------- 
 */ 
public class MyStack<T> { 
  private LinkedList<T> storage = new LinkedList<T>(); 
 
  public synchronized void push(T e) {//需要加上同步 
    storage.addFirst(e); 
  } 
 
  public T peek() { 
    return storage.getFirst(); 
  } 
 
  public void pop() { 
    storage.removeFirst(); 
  } 
 
  public boolean empty() { 
    return storage.isEmpty(); 
  } 
 
  @Override 
  public String toString() { 
    return storage.toString(); 
  } 
 
}

The following is a test class

/** 
 * @author 刘伊凡 
 * 
 */ 
public class StackTest { 
  public static void main(String[] args) { 
    MyStack<String> stack = new MyStack<String>(); 
    for(String s : "the prefect code".split(" ")){//LIFO 
      stack.push(s); 
    } 
    while(!stack.empty()){ 
      System.out.print(stack.peek()+" "); 
      stack.pop(); 
    } 

    System.out.println(); 
    for(char s : "写了个一句话倒起来说的程序".toCharArray()){//用例：正话反说 
      stack.push(String.valueOf(s)); 
    } 
    while(!stack.empty()){ 
      System.out.print(stack.peek()); 
      stack.pop(); 
    } 
  } 
}

It’s quite interesting. It made me think about it. At a school party before, the host During the interaction, people will go on stage to answer questions and win prizes. One of the questions is that the host says a sentence, and then asks the contestants to stand up and say, our program meets the needs, haha, we can use Java to cheat and learn what we have learned. Use

application scenarios of message queue to supplement (from the Internet)

I personally think that the main feature of message queue is asynchronous processing, and the main purpose is to reduce request responses Time and decoupling. Therefore, the main usage scenario is to put operations that are time-consuming and do not require immediate (synchronous) return results as messages into the message queue. At the same time, due to the use of message queues, as long as the message format remains unchanged, the sender and receiver of the message do not need to contact each other or be affected by each other, that is, decoupling and summarization.

Usage scenarios, for example:

Assume that the user registers in your software, and after the server receives the user's registration request, it will perform these operations:

Verify the user name and other information. If there is no problem, a user record will be added to the database.

If you register by email, you will be sent an email indicating that the registration is successful. Mobile phone registration will send a text message

to analyze the user's personal information in order to recommend some like-minded people to him in the future, or recommend him to those people

is sent to the user A system notification containing an operation guide

Wait...

But for the user, the registration function actually only requires the first step, as long as the server sends his After the account information is saved in the database, he can log in and do what he wants to do. As for other things, do they have to be completed in this request? Is it worth the user's time to wait for you to deal with something that doesn't matter to him? So actually after the first step is completed, the server can put other operations into the corresponding message queue and immediately return the user results, and the message queue will perform these operations asynchronously.

Or there is another situation where a large number of users register for your software at the same time. In high concurrency situations, the registration requests begin to have some problems. For example, the email interface cannot bear it, or the large amount of calculations when analyzing the information consumes the CPU. When fully loaded, there will be a situation where although user data records are quickly added to the database, they are stuck when sending emails or analyzing information, resulting in a significant increase in the response time of the request, or even a timeout, which is a bit uneconomical. . Faced with this situation, these operations are generally put into the message queue (producer-consumer model). The message queue processes it slowly, and at the same time, the registration request can be completed quickly without affecting the user's use of other functions.

So in the normal function development of the software, there is no need to deliberately look for usage scenarios of message queues. Instead, when a performance bottleneck occurs, check whether there are time-consuming operations in the business logic that can be processed asynchronously. If it exists, a message queue can be introduced to solve it. Otherwise, blindly using message queues may increase maintenance and development costs but fail to achieve considerable performance improvements, which is not worth the gain.

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