Spring Cloud(Finchley.RCI) (五) Spring Cloud创建服务消费者

Feign简介

Feign是一个声明式的伪Http客户端, 它使得写Http客户端变得简单, 使用Feign, 只需要创建一个接口并注解。它具有可插拔的注解特性, 可使用Feign注解和JAX-RS注解。Feign支持可插拔的编码器和解码器。Feign默认集成了Ribbon, 并和Eureka结合, 默认实现了负载均衡的效果。

Feign采用的是基于接口的注解

Feign整合了Ribbon

创建服务消费者

创建一个工程名为hello-spring-cloud-web-admin-feign的服务消费者项目, pom配置如下

<?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>com.funtl</groupId>
        <artifactId>hello-spring-cloud-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../hello-spring-cloud-dependencies/pom.xml</relativePath>
    </parent>

    <artifactId>hello-spring-cloud-web-admin-feign</artifactId>
    <packaging>jar</packaging>

    <name>hello-spring-cloud-web-admin-feign</name>
    <url>http://www.funtl.com</url>
    <inceptionYear>2018-Now</inceptionYear>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</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-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <dependency>
            <groupId>net.sourceforge.nekohtml</groupId>
            <artifactId>nekohtml</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.funtl.hello.spring.cloud.web.admin.feign.WebAdminFeignApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

创建WebAdminFeignApplication

package com.funtl.hello.spring.cloud.web.admin.feign;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class WebAdminFeignApplication {
    public static void main(String[] args) {
        SpringApplication.run(WebAdminFeignApplication.class, args);
    }
}

application.yml

spring:
  application:
    name: hello-spring-cloud-web-admin-feign
  thymeleaf:
    cache: false
    mode: LEGACYHTML5
    encoding: UTF-8
    servlet:
      content-type: text/html
server:
  port: 8765
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

创建Feign接口

通过@FeignClient(“服务名”)注解来指定调用哪个服务

package com.funtl.hello.spring.cloud.web.admin.feign.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value="hello-spring-cloud-service-admin")
public interface AdminService {

    @RequestMapping(value="hi", method= RequestMethod.GET)
    public String sayHi(@RequestParam String message);
}

创建测试用的Controller

package com.funtl.hello.spring.cloud.web.admin.feign.controller;

import com.funtl.hello.spring.cloud.web.admin.feign.service.AdminService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class AdminController {
    @Autowired
    private AdminService adminService;

    @RequestMapping(value="hi", method= RequestMethod.GET)
    public String sayHi(String message){
        return adminService.sayHi(message);
    }
}

测试访问

在浏览器上多次访问http://localhost:8765/hi?message=HelloFeign