RabbitMQ非官方教程（二）HelloWorld的Demo

這是官網教程，https://www.rabbitmq.com/tutorials/tutorial-one-java.html

用谷歌瀏覽器將網頁翻譯成中文看即可，這裏就簡單指一下消息傳遞過程

生產者 --> 交換器 --> 隊列 --> 消費者

生產者生成消息，然後將消息轉發到相應交換器中，通過一定規則匹配或綁定，交換器把消息轉發到對應的隊列中，隊列也會通過部分規則將消息發送個消費者。由於生產者、隊列、消費者都可以是多個存在的，加上消息在不同東西之間傳遞便顯得複雜起來。但開發過程不一定會用到這麼複雜的操作，今天先把demo寫一下。

 

這是本節的demo代碼地址：https://gitee.com/mjTree/javaDevelop/tree/master/testDemo

首先打開rabbitmq的服務，打開網頁(不清楚可以查看教程一)，之後用IDEA創建一個maven項目。

在pom.xml加入所需的相應依賴

<dependencies>
        <dependency>
            <groupId>com.rabbitmq</groupId>
            <artifactId>amqp-client</artifactId>
            <version>5.7.1</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.7.26</version>
        </dependency>

        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>5.5.1</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>io.dropwizard.metrics</groupId>
            <artifactId>metrics-core</artifactId>
            <version>4.1.0</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.assertj</groupId>
            <artifactId>assertj-core</artifactId>
            <version>3.13.2</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-core</artifactId>
            <version>3.0.0</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
            </plugin>
            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.22.2</version>
            </plugin>
        </plugins>
    </build>

在在mian/java下面新建com.myTest.RabbitMQ.First的包下面建立Send.java和Recv.java完成今天的demo。

如果代碼報錯Lambda expressions are not supported at language level '5'，是IDEA的配置問題，修改一下即可解決。

File > Project Structure > Project > Project SDK: Change it to Java 1.8.XX
File > Project Structure > Project > Language Level: SDK 8 (in my case SDK default was already 8)
File > Project Structure > Modules > Sources > SDK 8 (in my case SDK default was already 8)
File > Settings > Build, Execution, Deployment > Compiler > Java Compiler > Project bytecode version > 1.8
File > Settings > Build, Execution, Deployment > Compiler > Java Compiler > Per-module bytecode version > Target bytecode version > 1.8

來源：https://stackoverflow.com/questions/29921498/lambda-expressions-are-not-supported-at-this-language-level-idea/30102858

package com.mytest.rabbitMQ.First;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.DeliverCallback;

public class Recv {
    private final static String QUEUE_NAME = "hello";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.queueDeclare(QUEUE_NAME, false, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [x] Received '" + message + "'");
        };
        channel.basicConsume(QUEUE_NAME, true, deliverCallback, consumerTag -> { });
    }
}

之後兩個代碼運行沒有先後順尋，先運行Send之後可以在Rabbitmq網頁上查看到相應隊列和消息數；

之後再運行Recv消費掉消息之後網頁也會發生變化。