我要评论spring cloud stream 是一个构建消息驱动微服务的框架，该框架在spring boot的基础上整合了spring integrationg来连接消息代理中间件(rabbitmq, kafka等)，提供了个性化的自动化配置实现，并引入了发布-订阅、消费组、分区这三个核心概念。
应用程序通过input通道或者output通道来与spring cloud stream中binder（绑定器）交互，通过配置来binding. 而spring cloud stream的binder负责与中间件交互。
开发工具：intellij idea 2019.2.3
一、服务器端
1、创建项目
idea中创建一个新的springboot项目，名称为“spring-server”，springboot版本选择2.1.10，在选择dependencies(依赖)的界面勾选spring cloud discovery -> eureka server。
pom.xml完整内容如下：
<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="http://maven.apache.org/pom/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelversion>4.0.0</modelversion>
<parent>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-parent</artifactid>
<version>2.1.10.release</version>
<relativepath/> <!-- lookup parent from repository -->
</parent>
<groupid>com.example</groupid>
<artifactid>spring-server</artifactid>
<version>0.0.1-snapshot</version>
<name>spring-server</name>
<description>demo project for spring boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>greenwich.sr4</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-starter-netflix-eureka-server</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-test</artifactid>
<scope>test</scope>
</dependency>
</dependencies>
<dependencymanagement>
<dependencies>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-dependencies</artifactid>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencymanagement>
<build>
<plugins>
<plugin>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-maven-plugin</artifactid>
</plugin>
</plugins>
</build>
</project>
2、修改配置application.yml
修改端口号为8761；取消将自己信息注册到eureka服务器，不从eureka服务器抓取注册信息。
server:
port: 8761
eureka:
client:
register-with-eureka: false
fetch-registry: false
3、修改启动类代码
增加注解@enableeurekaserver
package com.example.springserver;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
import org.springframework.cloud.netflix.eureka.server.enableeurekaserver;
@springbootapplication
@enableeurekaserver
public class springserverapplication {
public static void main(string[] args) {
springapplication.run(springserverapplication.class, args);
}
}
二、消息生产者
1、创建项目
idea中创建一个新的springboot项目，名称为“spring-producer”，springboot版本选择2.1.10，在选择dependencies(依赖)的界面勾选web -> spring web，spring cloud discovery -> eureka discovery client。
打开pom.xml，添加依赖spring-cloud-starter-stream-rabbit，会自动引入spring-cloud-stream和spring-cloud-stream-binder。
pom.xml完整内容如下：
<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="http://maven.apache.org/pom/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelversion>4.0.0</modelversion>
<parent>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-parent</artifactid>
<version>2.1.10.release</version>
<relativepath/> <!-- lookup parent from repository -->
</parent>
<groupid>com.example</groupid>
<artifactid>spring-producer</artifactid>
<version>0.0.1-snapshot</version>
<name>spring-producer</name>
<description>demo project for spring boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>greenwich.sr4</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-web</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-starter-netflix-eureka-client</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-starter-stream-rabbit</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-test</artifactid>
<scope>test</scope>
</dependency>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-stream-test-support</artifactid>
<scope>test</scope>
</dependency>
</dependencies>
<dependencymanagement>
<dependencies>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-dependencies</artifactid>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencymanagement>
<build>
<plugins>
<plugin>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-maven-plugin</artifactid>
</plugin>
</plugins>
</build>
</project>
2、修改配置application.yml
pom.xml使用rabbitmq，默认情况下，连接本地的5672端口。下面这段rabbitmq也可省略。
server:
port: 8081
spring:
application:
name: spring-producer
eureka:
instance:
hostname: localhost
client:
serviceurl:
defaultzone: http://localhost:8761/eureka/
rabbitmq:
host: localhost
post: 5672
username: guest
password: guest
3、编写发送服务
方法sendorder使用@output("myinput")注解表示创建myinput的消息通道。调用该方法后，会向myinput通道投递消息。
如果不使用参数myinput，则使用方法名作为通道名称。
package com.example.springproducer;
import org.springframework.cloud.stream.annotation.output;
import org.springframework.messaging.subscribablechannel;
public interface sendservice {
@output("myinput")
subscribablechannel sendorder();
}
4、修改启动类代码
加入注解@enablebinding以开启spring容器的绑定功能，以sendservice.class为参数，spring容器启动时，会自动绑定sendservice接口中定义的通道。
package com.example.springproducer;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
import org.springframework.cloud.netflix.eureka.enableeurekaclient;
import org.springframework.cloud.stream.annotation.enablebinding;
@springbootapplication
@enableeurekaclient
@enablebinding(sendservice.class)
public class springproducerapplication {
public static void main(string[] args) {
springapplication.run(springproducerapplication.class, args);
}
}
5、添加一个控制器类
调用sendservice的发送方法，往服务器发送消息。
package com.example.springproducer;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.messaging.message;
import org.springframework.messaging.support.messagebuilder;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.requestmethod;
import org.springframework.web.bind.annotation.restcontroller;
@restcontroller
public class producercontroller {
@autowired
sendservice sendservice;
@requestmapping(value="/send",method= requestmethod.get)
public string sendrequest(){
//创建消息
message msg = messagebuilder.withpayload("hello world".getbytes()).build();
//发送消息
sendservice.sendorder().send(msg);
return "success";
}
}
三、消息消费者
1、创建项目
idea中创建一个新的springboot项目，名称为“spring-consumer”，springboot版本选择2.1.10，在选择dependencies(依赖)的界面勾选web -> spring web，spring cloud discovery -> eureka discovery client。
打开pom.xml，添加依赖
<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="http://maven.apache.org/pom/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelversion>4.0.0</modelversion>
<parent>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-parent</artifactid>
<version>2.1.10.release</version>
<relativepath/> <!-- lookup parent from repository -->
</parent>
<groupid>com.example</groupid>
<artifactid>spring-consumer</artifactid>
<version>0.0.1-snapshot</version>
<name>spring-consumer</name>
<description>demo project for spring boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>greenwich.sr4</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-web</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-starter-netflix-eureka-client</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-starter-stream-rabbit</artifactid>
</dependency>
<dependency>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-starter-test</artifactid>
<scope>test</scope>
</dependency>
</dependencies>
<dependencymanagement>
<dependencies>
<dependency>
<groupid>org.springframework.cloud</groupid>
<artifactid>spring-cloud-dependencies</artifactid>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencymanagement>
<build>
<plugins>
<plugin>
<groupid>org.springframework.boot</groupid>
<artifactid>spring-boot-maven-plugin</artifactid>
</plugin>
</plugins>
</build>
</project>
2、修改配置application.yml
server:
port: 8080
spring:
application:
name: spring-consumer
eureka:
instance:
hostname: localhost
client:
serviceurl:
defaultzone: http://localhost:8761/eureka/
rabbitmq:
host: localhost
post: 5672
username: guest
password: guest
3、缩写接受消息的通道接口
package com.example.springconsumer;
import org.springframework.cloud.stream.annotation.input;
import org.springframework.messaging.subscribablechannel;
public interface receiveservice {
@input("myinput")
subscribablechannel myinput();
}
4、修改启动类代码
同样绑定消息通道
package com.example.springconsumer;
import org.springframework.boot.springapplication;
import org.springframework.boot.autoconfigure.springbootapplication;
import org.springframework.cloud.stream.annotation.enablebinding;
import org.springframework.cloud.stream.annotation.streamlistener;
@springbootapplication
@enablebinding(receiveservice.class)
public class springconsumerapplication {
public static void main(string[] args) {
springapplication.run(springconsumerapplication.class, args);
}
//订阅myinput通道的消息
@streamlistener("myinput")
public void receive(byte[] msg){
system.out.println("接收到的消息：" + new string(msg));
}
}
5、测试
（1）检查服务里面的rabbitmq是否有启动（默认启动）；
（2）启动spring-server（8761端口）；
（3）启动spring-producer（8081端口）；
（4）启动spring-consumer（8080端口）；
（5）浏览器访问http://localhost:8081/send，spring-consumer项目的控制台输出：
接收到的消息：hello world
说明消费者已经可以从消息代理中获取到消息。
四、更换绑定器
上面使用了rabbitmq作为消息代理，如果使用kafka，可以更换maven依赖实现。
在生产者和消费者的pom.xml中，将spring-cloud-starter-stream-rabbit修改为spring-cloud-starter-stream-kafka。
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