RabbitMQ笔记二十三 ：异步RPC之二（使用Spring AMQP实现RPC异步调用）

2023年11月19日 265次阅读 来源: 二月_春风

使用Spring AMQP实现RPC异步调用

示列

服务器端

应用启动类代码，

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;

import java.util.concurrent.TimeUnit;

@ComponentScan
public class Application {
    public static void main(String[] args) throws Exception{
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Application.class);
        System.out.println("===server startup======");
        TimeUnit.SECONDS.sleep(120);
        context.close();
    }
}

配置类：
监听了sms队列，这个队列将会是客户端请求消息发送到的队列，配置了适配器，适配器中去调用服务，适配器返回的值就是服务端返回给客户端的RPC调用的结果

import org.springframework.amqp.core.AcknowledgeMode;
import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitAdmin;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
import org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MQConfig {

    @Bean
    public ConnectionFactory connectionFactory(){
        CachingConnectionFactory factory = new CachingConnectionFactory();
        factory.setUri("amqp://zhihao.miao:123456@192.168.1.131:5672");
        return factory;
    }

    @Bean
    public RabbitAdmin rabbitAdmin(ConnectionFactory connectionFactory){
        RabbitAdmin rabbitAdmin = new RabbitAdmin(connectionFactory);
        return rabbitAdmin;
    }

    @Bean
    public RabbitTemplate rabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        return rabbitTemplate;
    }

    @Bean
    public SimpleMessageListenerContainer messageListenerContainer(ConnectionFactory connectionFactory){
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        container.setQueueNames("sms");
        container.setAcknowledgeMode(AcknowledgeMode.NONE);
        //使用适配器的方式
        container.setMessageListener(new MessageListenerAdapter(new SendSMSHandler()));
        return container;
    }
}

处理器，处理器中调用具体的服务，我们此列子中处理器方法返回的值是boolean类型

import java.util.concurrent.TimeUnit;

public class SendSMSHandler {

    public boolean handleMessage(byte[] body){
        String _body = new String(body);
        System.out.println(_body);
        String[] sms = _body.split(":");
        String phone = sms[0];
        String content = sms[1];

        boolean is = SendSMSTool.sendSMS(phone,content);

        try {
            TimeUnit.SECONDS.sleep(6);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        return is;
    }
}

服务接口

public class SendSMSTool {

    public static boolean sendSMS(String phone,String content){
        System.out.println("发送短信内容：【"+content+"】到手机号："+phone);
        return phone.length() > 6;
    }
}

服务端步骤

  1. 消息处理方法，一定要有返回值，这个返回值就是就是server回复客户端的结果。比如我们SendSMSHandler.handleMessage方法返回的值。

客户端
应用启动类：

import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.support.CorrelationData;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;

import java.util.UUID;
import java.util.concurrent.TimeUnit;

@ComponentScan
public class Application {
    public static void main(String[] args) throws Exception{
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Application.class);

        RabbitTemplate rabbitTemplate = context.getBean(RabbitTemplate.class);

        //设置超时时间，单位是ms
        rabbitTemplate.setReplyTimeout(10000);

        String phone = "15634344321";
        String content ="周年庆，五折优惠";

        MessageProperties messageProperties = new MessageProperties();
        Message message = new Message((phone+":"+content).getBytes(),messageProperties);

        //rabbitTemplate.send("","sms",message);

        Message reply = rabbitTemplate.sendAndReceive("","sms",message,
                new CorrelationData(UUID.randomUUID().toString()));

        System.out.println(reply);
        System.out.println("message,body:"+new String(reply.getBody()));
        System.out.println("message,properties:"+reply.getMessageProperties());

        TimeUnit.SECONDS.sleep(30);
        context.close();
    }
}

配置类代码：

import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitAdmin;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MQConfig {

    @Bean
    public ConnectionFactory connectionFactory(){
        CachingConnectionFactory factory = new CachingConnectionFactory();
        factory.setUri("amqp://zhihao.miao:123456@192.168.1.131:5672");
        return factory;
    }

    @Bean
    public RabbitAdmin rabbitAdmin(ConnectionFactory connectionFactory){
        RabbitAdmin rabbitAdmin = new RabbitAdmin(connectionFactory);
        return rabbitAdmin;
    }

    @Bean
    public RabbitTemplate rabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        return rabbitTemplate;
    }
}

如果服务端睡眠6s，则客户端通过sendAndReceive方法接收到的Message对象为空，怎样设置呢？
客户端通过设置rabbitTemplate.setReplyTimeout(10000);就可以了。

客户端步骤

  1. 使用sendAndReceive方法发送消息，该方法返回一个Message对象，该对象就是server返回的结果
  2. sendAndReceive如果超过5s还没有收到结果，则返回null，这个超时时间可以通过rabbitTemplate.setReplyTimeout()来进行设置
  3. server端返回的结果一定要注意，和MessageConverter有关，默认的org.springframework.amqp.support.converter.SimpleMessageConverter会把基本的数据类型转换成Serializable对象，这样的话，client端接收的也是序列化的java对象，所以，需要合理设置MessageConverter。

示列代码中服务端返回给客户端的是Boolean类型,

启动服务端客户端代码：
服务器打印控制台打印：

15634344321:周年庆，五折优惠
发送短信内容：【周年庆，五折优惠】到手机号：15634344321

客户端控制台打印：

message,body:����sr��java.lang.Boolean� r�՜�����Z��valuexp�
message,properties:MessageProperties [headers={}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=application/x-java-serialized-object, contentEncoding=null, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=, receivedRoutingKey=amq.rabbitmq.reply-to.g2dkAB5yYWJiaXRAaVpicDFqY3d4N3NmYjFud3pyZWh5NloAAFu0AAAABwI=.kHL9zxtdQmtcxl0mQF8zrg==, receivedDelay=null, deliveryTag=1, messageCount=null, consumerTag=null, consumerQueue=null]

我们发现客户端接收到的数据乱码，将服务端的处理器的返回值改写成String类型的，

import java.util.concurrent.TimeUnit;

public class SendSMSHandler {

    public String handleMessage(byte[] body){
        String _body = new String(body);
        System.out.println(_body);
        String[] sms = _body.split(":");
        String phone = sms[0];
        String content = sms[1];

        boolean is = SendSMSTool.sendSMS(phone,content);

        try {
            TimeUnit.SECONDS.sleep(6);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        return is ? "success":"false";
    }
}

此时发现客户端接收的消息数据没有乱码，原因何在？我们总结一下就是服务器端处理器返回给客户端boolean类型，那么返回的消息数据就乱码，如果返回的是String类型，那么返回的消息数据就不会乱码。

之前我们学习了org.springframework.amqp.support.converter.MessageConverter接口，当客户端向服务端发送消息的时候会进行消息类型转换，调用了fromMessage方法，而当服务器返回给客户端的时候会将服务端的对象转换成Message对象，很明显调用的是toMessage方法。

我们知道org.springframework.amqp.support.converter.MessageConverter接口的默认实现是org.springframework.amqp.support.converter.SimpleMessageConverter，而toMessage方法的实现是在其继承的对象AbstractMessageConverter中，

我们看到其AbstractMessageConverter.toMessage方法的实现逻辑是：

    @Override
    public final Message toMessage(Object object, MessageProperties messageProperties)
            throws MessageConversionException {
        if (messageProperties == null) {
            messageProperties = new MessageProperties();
        }
        //将对象转换成Message对象
        Message message = createMessage(object, messageProperties);
        messageProperties = message.getMessageProperties();
        if (this.createMessageIds && messageProperties.getMessageId() == null) {
            messageProperties.setMessageId(UUID.randomUUID().toString());
        }
        return message;
    }

其createMessage方法就是将对象转换成Message对象，

    /**
     * Creates an AMQP Message from the provided Object.
     */
    @Override
    protected Message createMessage(Object object, MessageProperties messageProperties) throws MessageConversionException {
        byte[] bytes = null;
        if (object instanceof byte[]) {
            bytes = (byte[]) object;
            messageProperties.setContentType(MessageProperties.CONTENT_TYPE_BYTES);
        }
        else if (object instanceof String) {
            try {
                bytes = ((String) object).getBytes(this.defaultCharset);
            }
            catch (UnsupportedEncodingException e) {
                throw new MessageConversionException(
                        "failed to convert to Message content", e);
            }
            messageProperties.setContentType(MessageProperties.CONTENT_TYPE_TEXT_PLAIN);
            messageProperties.setContentEncoding(this.defaultCharset);
        }
        //因为boolean类型实现Serializable接口，所以会将其序列化
        else if (object instanceof Serializable) {
            try {
                bytes = SerializationUtils.serialize(object);
            }
            catch (IllegalArgumentException e) {
                throw new MessageConversionException(
                        "failed to convert to serialized Message content", e);
            }
            messageProperties.setContentType(MessageProperties.CONTENT_TYPE_SERIALIZED_OBJECT);
        }
        if (bytes != null) {
            messageProperties.setContentLength(bytes.length);
        }
        return new Message(bytes, messageProperties);
    }

我们在程序中将序列化对象直接转换成字符串所以乱码，而返回的是String类型的情形的时候先将字符串转换成相应的字节数组，然后返回new Message(bytes, messageProperties);就不会乱码。

继续探讨，当我们服务端返回的是一个对象的时候，客户端会返回空
返回的对象：

public class SendStatus {

    private String phone;

    private String result;

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getResult() {
        return result;
    }

    public void setResult(String result) {
        this.result = result;
    }
}

将该对象返回：

public class SendSMSHandler {

    public SendStatus handleMessage(byte[] body){
        String _body = new String(body);
        System.out.println(_body);
        String[] sms = _body.split(":");
        String phone = sms[0];
        String content = sms[1];

        boolean is = SendSMSTool.sendSMS(phone,content);
        SendStatus sendStatus = new SendStatus();
        sendStatus.setPhone(phone);
        sendStatus.setResult(is ? "SUCCESS":"FAILURE");
        return sendStatus;
    }
}

服务端控制台：

15634344321:周年庆，五折优惠
发送短信内容：【周年庆，五折优惠】到手机号：15634344321

客户端：

message,body:
message,properties:MessageProperties [headers={}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=application/octet-stream, contentEncoding=null, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=, receivedRoutingKey=amq.rabbitmq.reply-to.g2dkAB5yYWJiaXRAaVpicDFqY3d4N3NmYjFud3pyZWh5NloAAFxBAAAABwI=.01fOGW/nvS2nz6gKza+cjg==, receivedDelay=null, deliveryTag=1, messageCount=null, consumerTag=null, consumerQueue=null]

原因何在，因为我们定义的SendStatus不走createMessage中的所有if分支，最后返回的是null，怎么解决呢，要么自己去定义一个org.springframework.amqp.support.converter.MessageConverter实现，要么换一个默认的org.springframework.amqp.support.converter.MessageConverter实现。

改造后的示列

使用AMQP自带的消息类型转换器Jackson2JsonMessageConverter
服务端

应用启动类，

import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;

import java.util.concurrent.TimeUnit;

@ComponentScan
public class Application {
    public static void main(String[] args) throws Exception{
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Application.class);
        System.out.println("===server startup======");
        TimeUnit.SECONDS.sleep(120);
        context.close();
    }
}

配置类，添加自定义的消息转换器

import org.springframework.amqp.core.AcknowledgeMode;
import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitAdmin;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
import org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MQConfig {

    @Bean
    public ConnectionFactory connectionFactory(){
        CachingConnectionFactory factory = new CachingConnectionFactory();
        factory.setUri("amqp://zhihao.miao:123456@192.168.1.131:5672");
        return factory;
    }

    @Bean
    public RabbitAdmin rabbitAdmin(ConnectionFactory connectionFactory){
        RabbitAdmin rabbitAdmin = new RabbitAdmin(connectionFactory);
        return rabbitAdmin;
    }

    @Bean
    public RabbitTemplate rabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        return rabbitTemplate;
    }

    @Bean
    public SimpleMessageListenerContainer messageListenerContainer(ConnectionFactory connectionFactory){
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        container.setQueueNames("sms");
        container.setAcknowledgeMode(AcknowledgeMode.NONE);
        //使用适配器的方式
        container.setMessageListener(new MessageListenerAdapter(new SendSMSHandler(),new Jackson2JsonMessageConverter()));
        return container;
    }
}

处理器handler，返回自定义的SendStatus类型

import java.util.concurrent.TimeUnit;

public class SendSMSHandler {

    public SendStatus handleMessage(byte[] body){
        String _body = new String(body);
        System.out.println(_body);
        String[] sms = _body.split(":");
        String phone = sms[0];
        String content = sms[1];

        boolean is = SendSMSTool.sendSMS(phone,content);
        SendStatus sendStatus = new SendStatus();
        sendStatus.setPhone(phone);
        sendStatus.setResult(is ? "SUCCESS":"FAILURE");

        try {
            TimeUnit.SECONDS.sleep(6);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        return sendStatus;
    }
}

接口服务，

public class SendSMSTool {

    public static boolean sendSMS(String phone,String content){
        System.out.println("发送短信内容：【"+content+"】到手机号："+phone);
        return phone.length() > 6;
    }
}

服务端返回的对象，

public class SendStatus {
    private String phone;

    private String result;

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getResult() {
        return result;
    }

    public void setResult(String result) {
        this.result = result;
    }
}

客户端
应用启动类，

import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.support.CorrelationData;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;

import java.util.UUID;
import java.util.concurrent.TimeUnit;

@ComponentScan
public class Application {
    public static void main(String[] args) throws Exception{
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Application.class);

        RabbitTemplate rabbitTemplate = context.getBean(RabbitTemplate.class);

        //设置超时时间，单位是ms
        rabbitTemplate.setReplyTimeout(10000);

        String phone = "15634344321";
        String content ="周年庆，五折优惠";

        MessageProperties messageProperties = new MessageProperties();
        Message message = new Message((phone+":"+content).getBytes(),messageProperties);

        //rabbitTemplate.send("","sms",message);

        Message reply = rabbitTemplate.sendAndReceive("","sms",message,
                new CorrelationData(UUID.randomUUID().toString()));

        System.out.println(reply);
        System.out.println("message,body:"+new String(reply.getBody()));
        System.out.println("message,properties:"+reply.getMessageProperties());

        TimeUnit.SECONDS.sleep(30);
        context.close();
    }
}

配置类

import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitAdmin;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MQConfig {

    @Bean
    public ConnectionFactory connectionFactory(){
        CachingConnectionFactory factory = new CachingConnectionFactory();
        factory.setUri("amqp://zhihao.miao:123456@192.168.1.131:5672");
        return factory;
    }

    @Bean
    public RabbitAdmin rabbitAdmin(ConnectionFactory connectionFactory){
        RabbitAdmin rabbitAdmin = new RabbitAdmin(connectionFactory);
        return rabbitAdmin;
    }

    @Bean
    public RabbitTemplate rabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        return rabbitTemplate;
    }
}

启动服务器客户端，客户端返回

message,body:{"phone":"15634344321","result":"SUCCESS"}
message,properties:MessageProperties [headers={__TypeId__=rpc.server.SendStatus}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=application/json, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=, receivedRoutingKey=amq.rabbitmq.reply-to

返回了SendStatus的JSON格式，因为使用了Jackson2JsonMessageConverter消息类型转换器。

    原文作者：二月_春风
    原文地址: https://www.jianshu.com/p/24b88ccfb019
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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