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This article is about how Spring Cloud clusters use Zuul. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Spring Cloud clusters use Zuul

In the example in the previous section, Zuul forwards the request to a Web project for processing, and if the request is not a Web project, but the entire micro-service cluster, then Zuul will become the gateway to the entire cluster. Before joining Zuul, the structure of the Spring Cloud cluster is shown in figure 7-3.

Figure 7-3 original Spring Cloud cluster structure

After joining the Zuul gateway for the micro-service cluster, the structure is shown in figure 7-4.

Figure 7-4 Cluster structure after joining Zuul

Before delving into Zuul, build the test project for this chapter as shown in figure 7-4.

Cluster building

Suppose you need to implement a book sales business, and you need to call the service of the book module in the sales module to find books. Based on this, this section of the case establishes the following items:

Zuul-eureka-server:Eureka server, application port is 8761, readers can get the source code from the following directory: codes\ 07\ 03\ zuul-eureka-server.

Zuul-book-service: book module, which belongs to the service provider, provides "/ book/ {bookId}" service, which is used to find books and finally returns the JSON string of Book. The application port is 9000 and the code directory codes\ 07\ 03\ zuul-book-service.

Zuul-sale-service: sales module, belonging to the service caller, publishes the sales service "/ sale-book/ {bookId}". In this service, zuul-book-service is called to find Book. The application port is 9100 and the code directory is codes\ 07\ 03\ zuul-sale-service.

The service published by the book module "zuul-book-service" only returns a simple Book object. The controller code is as follows:

@ RequestMapping (value = "/ book/ {bookId}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE) public Book findBook (@ PathVariable Integer bookId) {Book book = new Book (); book.setId (bookId); book.setName ("Workflow handout"); book.setAuthor ("Yang Enxiong"); return book;}

The service released by the sales module "zuul-sale-service". The related code is as follows:

@ FeignClient ("zuul-book-service") / / declares calling the book service public interface BookService {/ * invokes the interface of the book service, and gets a Book instance * / @ RequestMapping (method = RequestMethod.GET, value = "/ book/ {bookId}") Book getBook (@ PathVariable ("bookId") Integer bookId);} @ RestControllerpublic class SaleController {@ Autowired private BookService bookService @ RequestMapping (value = "/ sale-book/ {bookId}", method = RequestMethod.GET) public String saleBook (@ PathVariable Integer bookId) {/ / call the book service to find Book book = bookService.getBook (bookId) / / console input to simulate sales System.out.println ("sales module handles sales, books to be sold id:" + book.getId () + ", title:" + book.getName ()); / / successful sales return "SUCCESS";}}

Sell the service of the module, use Feign to call the service of the book module to obtain the Book instance, and then output the information in the console. In practical application, the sales process will be more complex, for example, it may involve payment and so on. In this example, only simple output is made for the sake of simplicity. Next, create the gateway project.

Route to cluster service

Based on the previous section, create a new Maven project named "zuul-gateway" (code directory codes\ 07\ 03\ zuul-gateway) and add the following dependencies to pom.xml:

Org.springframework.cloud spring-cloud-starter-config org.springframework.cloud spring-cloud-starter-eureka org.springframework.cloud spring-cloud-starter-zuul org.apache.httpcomponents httpclient 4.5.3

Create a new application class, as shown in listing 7-3.

Listing 7-3:

Codes\ 07\ 03\ zuul-gateway\ src\ main\ java\ org\ crazyit\ cloud\ GatewayApplication.java

@ EnableZuulProxy@SpringBootApplicationpublic class GatewayApplication {public static void main (String [] args) {new SpringApplicationBuilder (GatewayApplication.class) .properties ("server.port=8080") .run (args);}}

The application class is the same as the previous example, annotated with @ EnableZuulProxy, but because the gateway project needs to be added to the cluster, you need to modify the configuration file to register with the Eureka server. The configuration file for this example is shown in listing 7-4.

Listing 7-4:codes\ 07\ 03\ zuul-gateway\ src\ main\ resources\ application.yml

Spring: application: name: zuul-gatewayeureka: instance: hostname: localhost client: serviceUrl: defaultZone: http://localhost:8761/eureka/zuul: routes: sale: path: / sale/** serviceId: zuul-sale-service

Using the configuration of eureka, register yourself with 8761 Eureka. When configuring Zuul, declare that all "/ sale/**" requests will be forwarded to the service whose Id is "zuul-sale-service" for processing.

In general, after serviceId is configured, a filter called RibbonRoutingFilter will be used during the "routing" phase of the request, which will call Ribbon's API to implement load balancing, and HttpClient will be called by default to invoke the cluster service.

Start the cluster in the following order:

Start zuul-eureka-server (Eureka server).

Start zuul-book-service (service provider).

Start zuul-sale-service (the service caller).

Start zuul-gateway (Cluster Gateway).

Visit: http://localhost:8080/sale/sale-book/1 in the browser and return the "SUCCESS" string. In the console of the sales module, you can see the output as follows:

Sales module handles sales, book to be sold id: 1, title: Workflow handout

According to the output, both the sales module and the book module are called. This example involves four projects, and figure 7-5 shows the structure of the example to help readers understand it.

Figure 7-5 the structure of this example

Zuul Http client

We know that Ribbon is used to achieve load balancing. After selecting the appropriate server, Ribbon calls the REST client API to invoke the cluster service. By default, the cluster service is invoked using HttpClient's API. In addition to HttpClient, you can also use OkHttpClient, and com.netflix.niws.client.http.RestClient,RestClient is no longer recommended, if you want to enable OkHttpClient, you can add the following configuration: ribbon.okhttp.enabled=true. In addition to this configuration, add OkHttpClient dependencies to pom.xml:

Com.squareup.okhttp3 okhttp, thank you for your reading! This is the end of this article on "how to use Zuul in Spring Cloud clusters". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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