第二章-集成spring

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本章主要介绍了spring REST服务以及与JMS、RabbitMQ的集成。

构建一个REST服务

常用的几个请求方式注解。
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案例：
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允许XML输出

[允许XML输出]
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@RequestMapping(path="/design", produces={"application/json", "text/xml"})

url传参

[url传参]
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@GetMapping("/{id}")
public Taco tacoById(@PathVariable("id") Long id) {
	Optional<Taco> optTaco = tacoRepo.findById(id);
	if (optTaco.isPresent()) {
		return optTaco.get();
	}
	return null;
}

url返回404

[返回404]
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@GetMapping("/{id}")
public ResponseEntity<Taco> tacoById(@PathVariable("id") Long id) {
	Optional<Taco> optTaco = tacoRepo.findById(id);
	if (optTaco.isPresent()) {
		return new ResponseEntity<>(optTaco.get(), HttpStatus.OK);
	}
	return new ResponseEntity<>(null, HttpStatus.NOT_FOUND);
}

使用REST服务

使用RestTemplate使用REST端点

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配置RestTemplate

[spring配置类]
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@Bean
public RestTemplate restTemplate() {
	return new RestTemplate();
}

获得资源（Getting resouces）

[查询：getForObject()]
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public Ingredient getIngredientById(String ingredientId) {
	Map<String,String> urlVariables = new HashMap<>();
	urlVariables.put("id", ingredientId);
	return rest.getForObject("http://localhost:8080/ingredients/{id}",
		Ingredient.class, urlVariables);
}
[查询：URI+getForObject()]
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public Ingredient getIngredientById(String ingredientId) {
	Map<String,String> urlVariables = new HashMap<>();
	urlVariables.put("id", ingredientId);
	URI url = UriComponentsBuilder
		.fromHttpUrl("http://localhost:8080/ingredients/{id}")
		.build(urlVariables);
	return rest.getForObject(url, Ingredient.class);
}
[查询：getForEntity()]
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public Ingredient getIngredientById(String ingredientId) {
	ResponseEntity<Ingredient> responseEntity =
		rest.getForEntity("http://localhost:8080/ingredients/{id}",
			Ingredient.class, ingredientId);
	log.info("Fetched time: " +
		responseEntity.getHeaders().getDate());
	return responseEntity.getBody();
}

更新资源（Putting resouces）

[新增或编辑]
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public void updateIngredient(Ingredient ingredient) {
	rest.put("http://localhost:8080/ingredients/{id}",
		ingredient,
		ingredient.getId());
}

删除资源（DELETEing resources）

[删除]
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public void deleteIngredient(Ingredient ingredient) {
	rest.delete("http://localhost:8080/ingredients/{id}",
		ingredient.getId());
}

发布资源（POSTing resource data）

[发布资源]
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// 方式一
public Ingredient createIngredient(Ingredient ingredient) {
	return rest.postForObject("http://localhost:8080/ingredients",
							ingredient,
							Ingredient.class);
}
// 方式二
public URI createIngredient(Ingredient ingredient) {
	return rest.postForLocation("http://localhost:8080/ingredients",
		ingredient);
}
// 方式三
public Ingredient createIngredient(Ingredient ingredient) {
	ResponseEntity<Ingredient> responseEntity =
		rest.postForEntity("http://localhost:8080/ingredients",
			ingredient,
			Ingredient.class);
	log.info("New resource created at " +
		responseEntity.getHeaders().getLocation());
	return responseEntity.getBody();
}

异步发送消息

使用JMS发送消息

安装JMS

  1. 添加依赖

    [pom.xml]
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    <dependency>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-activemq</artifactId>
    </dependency>

  2. 修改spring配置文件

    [spring.yml]
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    spring:
    	activemq:
    		broker-url: tcp://activemq.tacocloud.com
    		user: tacoweb
    		password: l3tm31n

使用JmsTemplate发送消息

JmsTemplate有几个用于发送消息的方法，包括以下方法：

[JmsTemplate核心方法]
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// Send raw messages
void send(MessageCreator messageCreator) throws JmsException;
void send(Destination destination, MessageCreator messageCreator)
throws JmsException;
void send(String destinationName, MessageCreator messageCreator)
throws JmsException;
// Send messages converted from objects
void convertAndSend(Object message) throws JmsException;
void convertAndSend(Destination destination, Object message)
throws JmsException;
void convertAndSend(String destinationName, Object message)
throws JmsException;
// Send messages converted from objects with post-processing
void convertAndSend(Object message,
MessagePostProcessor postProcessor) throws JmsException;
void convertAndSend(Destination destination, Object message,
MessagePostProcessor postProcessor) throws JmsException;
void convertAndSend(String destinationName, Object message,
MessagePostProcessor postProcessor) throws JmsException;
编写发送方法
[send()]
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@Service
public class JmsOrderMessagingService implements OrderMessagingService {
	private JmsTemplate jms;
	@Autowired
	public JmsOrderMessagingService(JmsTemplate jms) {
		this.jms = jms;
	}
	/**@Override
	public void sendOrder(Order order) {
		jms.send(new MessageCreator() {
					 @Override
					 public Message createMessage(Session session)
						 throws JMSException {
						 return session.createObjectMessage(order);
					 }
				 }
		);
	}*/
	// 简化版
	@Override
	public void sendOrder(Order order) {
		jms.send(session -> session.createObjectMessage(order));
	}
}
指定发送目的地
[配置目的地]
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// 1.spring.yml文件
spring:
	jms:
		template:
			default-destination: tacocloud.order.queue

// 2.配置类
@Bean
public Destination orderQueue() {
	return new ActiveMQQueue("tacocloud.order.queue");
}	

// 3.注入到service类，JmsOrderMessagingService
private Destination orderQueue;
@Autowired
public JmsOrderMessagingService(JmsTemplate jms,
								Destination orderQueue) {
	this.jms = jms;
	this.orderQueue = orderQueue;
}
...
@Override
public void sendOrder(Order order) {
	jms.send(
		orderQueue,
		session -> session.createObjectMessage(order));
}

// 4.使用类似这样的目标对象指定目标，使您有机会配置目标，而不仅仅是目标名称。
@Override
public void sendOrder(Order order) {
	jms.send(
		"tacocloud.order.queue",
		session -> session.createObjectMessage(order));
}
发送前对消息进行转换
[代码块]
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@Override
public void sendOrder(Order order) {
	jms.convertAndSend("tacocloud.order.queue", order);
}
配置消息转换器
[代码块]
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public interface MessageConverter {
	Message toMessage(Object object, Session session)
		throws JMSException, MessageConversionException;
	Object fromMessage(Message message);
}

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[MappingJackson2MessageConverter]
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@Bean
public MappingJackson2MessageConverter messageConverter() {
	MappingJackson2MessageConverter messageConverter =
		new MappingJackson2MessageConverter();
	messageConverter.setTypeIdPropertyName("_typeId");
	return messageConverter;
}
后期处理消息

在消息中添加一个自定义头。

[代码块]
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jms.send("tacocloud.order.queue",
	session -> {
		Message message = session.createObjectMessage(order);
		message.setStringProperty("X_ORDER_SOURCE", "WEB");
});
// 案例
jms.convertAndSend("tacocloud.order.queue", order, new MessagePostProcessor() {
	@Override
	public Message postProcessMessage(Message message) throws JMSException {
		message.setStringProperty("X_ORDER_SOURCE", "WEB");
		return message;
	}
});
// 案例-优化
jms.convertAndSend("tacocloud.order.queue", order,
	message -> {
		message.setStringProperty("X_ORDER_SOURCE", "WEB");
	return message;
});
// 特殊情况
@GetMapping("/convertAndSend/order")
public String convertAndSendOrder() {
	Order order = buildOrder();
	jms.convertAndSend("tacocloud.order.queue", order,
		this::addOrderSource);
	return "Convert and sent order";
}
private Message addOrderSource(Message message) throws JMSException {
	message.setStringProperty("X_ORDER_SOURCE", "WEB");
	return message;
}

接收JMS消息

接收JMS TEMPLATE

核心方法：

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Message receive() throws JmsException;
Message receive(Destination destination) throws JmsException;
Message receive(String destinationName) throws JmsException;
Object receiveAndConvert() throws JmsException;
Object receiveAndConvert(Destination destination) throws JmsException;
Object receiveAndConvert(String destinationName) throws JmsException;

案例：

[代码块]
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// 案例一
@Component
public class JmsOrderReceiver implements OrderReceiver {
	private JmsTemplate jms;
	private MessageConverter converter;
	@Autowired
	public JmsOrderReceiver(JmsTemplate jms, MessageConverter converter) {
		this.jms = jms;
		this.converter = converter;
	}
	public Order receiveOrder() {
		Message message = jms.receive("tacocloud.order.queue");
		return (Order) converter.fromMessage(message);
	}
}
// 案例二
@Component
public class JmsOrderReceiver implements OrderReceiver {
	private JmsTemplate jms;
	@Autowired
	public JmsOrderReceiver(JmsTemplate jms) {
		this.jms = jms;
	}
	public Order receiveOrder() {
		return (Order) jms.receiveAndConvert("tacocloud.order.queue");
	}
}
定义消息监听器
[代码块]
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@Component
public class OrderListener {
	private KitchenUI ui;
	@Autowired
	public OrderListener(KitchenUI ui) {
		this.ui = ui;
	}
	@JmsListener(destination = "tacocloud.order.queue")
	public void receiveOrder(Order order) {
		ui.displayOrder(order);
	}
}

使用RabbitMQ and AMQP

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向Spring添加RabbitMQ

  1. 添加RabbitMQ依赖

    [代码块]
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    <dependency>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>

  2. 添加RabbitMQ配置文件
    Alt text

    [代码块]
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    spring:
    	profiles: prod
    	rabbitmq:
    		host: rabbit.tacocloud.com
    		port: 5673
    		username: tacoweb
    		password: l3tm31n
使用RabbitTemplate发送消息

RabbitTemplate几个核心方法：

[代码块]
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// Send raw messages
void send(Message message) throws AmqpException;
void send(String routingKey, Message message) throws AmqpException;
void send(String exchange, String routingKey, Message message)
throws AmqpException;
// Send messages converted from objects
void convertAndSend(Object message) throws AmqpException;
void convertAndSend(String routingKey, Object message)
throws AmqpException;
void convertAndSend(String exchange, String routingKey,
Object message) throws AmqpException;
// Send messages converted from objects with post-processing
void convertAndSend(Object message, MessagePostProcessor mPP)
throws AmqpException;
void convertAndSend(String routingKey, Object message,
MessagePostProcessor messagePostProcessor)
throws AmqpException;
void convertAndSend(String exchange, String routingKey,
Object message,
MessagePostProcessor messagePostProcessor)
throws AmqpException;

案例：

[1.代码块]
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@Service
public class RabbitOrderMessagingService
	implements OrderMessagingService {
	private RabbitTemplate rabbit;
	@Autowired
	public RabbitOrderMessagingService(RabbitTemplate rabbit) {
		this.rabbit = rabbit;
	}
	public void sendOrder(Order order) {
		MessageConverter converter = rabbit.getMessageConverter();
		MessageProperties props = new MessageProperties();
		Message message = converter.toMessage(order, props);
		rabbit.send("tacocloud.order", message);
	}
	// 消息转换
	public void sendOrder(Order order) {
		rabbit.convertAndSend("tacocloud.order", order);
	}
}
[2.spring.yml文件]
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spring:
	rabbitmq:
	template:
		exchange: tacocloud.orders
		routing-key: kitchens.central
配置消息转换器
[spring配置类]
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@Bean
public MessageConverter messageConverter() {
	return new Jackson2JsonMessageConverter();
}
设置消息属性
[代码块]
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public void sendOrder(Order order) {
	MessageConverter converter = rabbit.getMessageConverter();
	MessageProperties props = new MessageProperties();
	props.setHeader("X_ORDER_SOURCE", "WEB");
	Message message = converter.toMessage(order, props);
	rabbit.send("tacocloud.order", message);
}

// 方式二
@Override
public void sendOrder(Order order) {
	rabbit.convertAndSend("tacocloud.order.queue", order,
		new MessagePostProcessor() {
			@Override
			public Message postProcessMessage(Message message)
				throws AmqpException {
				MessageProperties props = message.getMessageProperties();
				props.setHeader("X_ORDER_SOURCE", "WEB");
				return message;
			}
		});
}

从RabbitMQ接收消息

几个关键方法：

[代码块]
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// Receive messages
Message receive() throws AmqpException;
Message receive(String queueName) throws AmqpException;
Message receive(long timeoutMillis) throws AmqpException;
Message receive(String queueName, long timeoutMillis) throws AmqpException;
// Receive objects converted from messages
Object receiveAndConvert() throws AmqpException;
Object receiveAndConvert(String queueName) throws AmqpException;
Object receiveAndConvert(long timeoutMillis) throws AmqpException;
Object receiveAndConvert(String queueName, long timeoutMillis) throws
AmqpException;
// Receive type-safe objects converted from messages
<T> T receiveAndConvert(ParameterizedTypeReference<T> type) throws
AmqpException;
<T> T receiveAndConvert(String queueName, ParameterizedTypeReference<T> type)
throws AmqpException;
<T> T receiveAndConvert(long timeoutMillis, ParameterizedTypeReference<T>
type) throws AmqpException;
<T> T receiveAndConvert(String queueName, long timeoutMillis,
ParameterizedTypeReference<T> type)
throws AmqpException;

案例：

[1.代码块]
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@Component
public class RabbitOrderReceiver {
	private RabbitTemplate rabbit;
	private MessageConverter converter;
	@Autowired
	public RabbitOrderReceiver(RabbitTemplate rabbit) {
		this.rabbit = rabbit;
		this.converter = rabbit.getMessageConverter();
	}
	public Order receiveOrder() {
		Message message = rabbit.receive("tacocloud.orders");
		return message != null
			? (Order) converter.fromMessage(message)
			: null;
	}
	// 1.延迟30000毫秒接收
	public Order receiveOrder() {
		Message message = rabbit.receive("tacocloud.order.queue", 30000);
		return message != null
			? (Order) converter.fromMessage(message)
			: null;
	}
	// 2-1消息转换器接收
	public Order receiveOrder() {
		return (Order) rabbit.receiveAndConvert("tacocloud.order.queue");
	}
	// 2-2.消息转换器接收
	public Order receiveOrder() {
		return rabbit.receiveAndConvert("tacocloud.order.queue",
			new ParameterizedTypeReference<Order>() {});
	}
}
[2.spring.yml配置文件]
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spring:
	rabbitmq:
		template:
			receive-timeout: 30000

使用侦听器处理RABBITMQ消息

[代码块]
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@Component
public class OrderListener {
	private KitchenUI ui;
	@Autowired
	public OrderListener(KitchenUI ui) {
		this.ui = ui;
	}
	@RabbitListener(queues = "tacocloud.order.queue")
	public void receiveOrder(Order order) {
		ui.displayOrder(order);
	}
}

消息传递与Kafka（略）
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