Spring Cloud（二）Feign声明式http客户端

一、引言

什么是Feign

　　Feign远程调用，核心就是通过一系列的封装和处理，以JAVA注解的方式定义的远程调用API接口，最终转换成HTTP的请求形式。然后将HTTP的请求的响应结果，解析成JAVA Bean，返回给调用方，实现远程接口调用。

　　Feign个人理解实际上是一种对RPC远程过程调用的一种实现，通过注解可以很方便的去进行RPC调用，减少配置。

二、Feign调用实例

　　我们需要创建2个工程：order-server、gds-server，然后分别在其中定义出controller来模拟订单系统调用商品系统的业务流程。

gds-server

pom.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 4     <modelVersion>4.0.0</modelVersion>
 5     <groupId>com.zhbf</groupId>
 6     <artifactId>gds-server</artifactId>
 7     <version>0.0.1-SNAPSHOT</version>
 8     <name>gds-server</name>
 9     <description>商品服务【有梦想的肥宅】</description>
10 
11     <parent>
12         <groupId>org.springframework.boot</groupId>
13         <artifactId>spring-boot-starter-parent</artifactId>
14         <version>1.5.6.RELEASE</version>
15         <relativePath/>
16     </parent>
17 
18     <properties>
19         <java.version>1.8</java.version>
20         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
21         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
22         <spring-boot.version>1.5.6.RELEASE</spring-boot.version><!--Spring Boot版本-->
23         <spring-cloud.version>1.4.6.RELEASE</spring-cloud.version><!--Spring Cloud版本-->
24     </properties>
25 
26     <dependencyManagement>
27         <dependencies>
28             <!--指定下载源和使用Spring Boot的版本-->
29             <dependency>
30                 <groupId>org.springframework.boot</groupId>
31                 <artifactId>spring-boot-dependencies</artifactId>
32                 <version>${spring-boot.version}</version>
33                 <type>pom</type>
34                 <scope>import</scope>
35             </dependency>
36             <!--指定下载源和使用Spring Cloud的版本-->
37             <dependency>
38                 <groupId>org.springframework.cloud</groupId>
39                 <artifactId>spring-cloud-dependencies</artifactId>
40                 <version>Edgware.SR5</version>
41                 <type>pom</type>
42                 <scope>import</scope>
43             </dependency>
44         </dependencies>
45     </dependencyManagement>
46 
47 
48     <dependencies>
49         <!--引入Spring Boot依赖-->
50         <dependency>
51             <groupId>org.springframework.boot</groupId>
52             <artifactId>spring-boot-starter</artifactId>
53         </dependency>
54         <!--引入lombok-->
55         <dependency>
56             <groupId>org.projectlombok</groupId>
57             <artifactId>lombok</artifactId>
58             <optional>true</optional>
59         </dependency>
60         <!--引入Spring Cloud的Eureka依赖-->
61         <dependency>
62             <groupId>org.springframework.cloud</groupId>
63             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
64             <version>${spring-cloud.version}</version>
65         </dependency>
66         <!--引入fastjson依赖-->
67         <dependency>
68             <groupId>com.alibaba</groupId>
69             <artifactId>fastjson</artifactId>
70             <version>1.2.76</version>
71         </dependency>
72         <!--服务调用-->
73         <dependency>
74             <groupId>org.springframework.cloud</groupId>
75             <artifactId>spring-cloud-starter-openfeign</artifactId>
76         </dependency>
77     </dependencies>
78 
79 </project>
View Code

controller

/**
 * @author 有梦想的肥宅
 * @date 2021/9/6
 */
@RestController
public class GdsController {

    @RequestMapping("/getGdsInfo")
    public Map getGdsInfo(@RequestParam String gdsId) {
        Map gdsInfo = new HashMap();
        gdsInfo.put("gdsId", gdsId);
        gdsInfo.put("gdsName", "测试商品名称");
        gdsInfo.put("shopName", "【有梦想的肥宅】小店");
        return gdsInfo;
    }
}

application.yml

#应用名称
spring:
    application:
        name: GDS-SERVER

#服务端口
server:
  port: 9092

#Eureka配置
eureka:
    client:
        service-url:
            defaultZone: http://${eureka.instance.hostname}:9090/eureka
    instance:
        hostname: 127.0.0.1

GdsServerApplication.java【启动类】

@SpringBootApplication
@EnableDiscoveryClient  //服务注册发现
@EnableFeignClients  //服务调用
public class GdsServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(GdsServerApplication.class, args);
    }

}

order-server

pom.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 4     <modelVersion>4.0.0</modelVersion>
 5     <groupId>com.zhbf</groupId>
 6     <artifactId>order-server</artifactId>
 7     <version>0.0.1-SNAPSHOT</version>
 8     <name>order-server</name>
 9     <description>订单服务【有梦想的肥宅】</description>
10 
11     <parent>
12         <groupId>org.springframework.boot</groupId>
13         <artifactId>spring-boot-starter-parent</artifactId>
14         <version>1.5.6.RELEASE</version>
15         <relativePath/>
16     </parent>
17 
18     <properties>
19         <java.version>1.8</java.version>
20         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
21         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
22         <spring-boot.version>1.5.6.RELEASE</spring-boot.version><!--Spring Boot版本-->
23         <spring-cloud.version>1.4.6.RELEASE</spring-cloud.version><!--Spring Cloud版本-->
24     </properties>
25 
26     <dependencyManagement>
27         <dependencies>
28             <!--指定下载源和使用Spring Boot的版本-->
29             <dependency>
30                 <groupId>org.springframework.boot</groupId>
31                 <artifactId>spring-boot-dependencies</artifactId>
32                 <version>${spring-boot.version}</version>
33                 <type>pom</type>
34                 <scope>import</scope>
35             </dependency>
36             <!--指定下载源和使用Spring Cloud的版本-->
37             <dependency>
38                 <groupId>org.springframework.cloud</groupId>
39                 <artifactId>spring-cloud-dependencies</artifactId>
40                 <version>Edgware.SR5</version>
41                 <type>pom</type>
42                 <scope>import</scope>
43             </dependency>
44         </dependencies>
45     </dependencyManagement>
46 
47 
48     <dependencies>
49         <!--引入Spring Boot依赖-->
50         <dependency>
51             <groupId>org.springframework.boot</groupId>
52             <artifactId>spring-boot-starter</artifactId>
53         </dependency>
54         <!--引入lombok-->
55         <dependency>
56             <groupId>org.projectlombok</groupId>
57             <artifactId>lombok</artifactId>
58             <optional>true</optional>
59         </dependency>
60         <!--引入Spring Cloud的Eureka依赖-->
61         <dependency>
62             <groupId>org.springframework.cloud</groupId>
63             <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
64             <version>${spring-cloud.version}</version>
65         </dependency>
66         <!--引入fastjson依赖-->
67         <dependency>
68             <groupId>com.alibaba</groupId>
69             <artifactId>fastjson</artifactId>
70             <version>1.2.76</version>
71         </dependency>
72         <!--服务调用-->
73         <dependency>
74             <groupId>org.springframework.cloud</groupId>
75             <artifactId>spring-cloud-starter-openfeign</artifactId>
76         </dependency>
77     </dependencies>
78 </project>
View Code

调用商品服务的fegin接口

/**
 * 调用商品服务的fegin接口
 *
 * @author 有梦想的肥宅
 */
@FeignClient(value = "GDS-SERVER", path = "/")//这里表示使用feign去调用应用名为GDS-SERVER的内部服务
public interface OutGdsApi {
    /**
     * 查询商品信息
     */
    @RequestMapping("/getGdsInfo")//表示通过feign发送http请求到GDS-SERVER的应用，地址映射为"/getGdsInfo"
    Map getGdsInfo(@RequestParam("gdsId") String gdsId);
}

controller

/**
 * @author 有梦想的肥宅
 * @date 2021/9/6
 */
@RestController
public class OrderController {

    @Autowired
    private OutGdsApi outGdsApi;//自动注入调用商品服务的fegin接口

    @RequestMapping("/showOrderInfo")
    public String showOrderInfo() {
        Map orderInfo = new HashMap();
        orderInfo.put("orderId", 1);
        orderInfo.put("gdsInfo", outGdsApi.getGdsInfo("1"));
        return JSON.toJSONString(orderInfo);
    }
}

application.yml

#应用名称
spring:
    application:
        name: OREDER-SERVER

#服务端口
server:
  port: 9091

#Eureka配置
eureka:
    client:
        service-url:
            defaultZone: http://${eureka.instance.hostname}:9090/eureka
    instance:
        hostname: 127.0.0.1

OrderServerApplication.java【启动类】

@SpringBootApplication
@EnableDiscoveryClient  //服务注册发现
@EnableFeignClients  //服务调用
public class OrderServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderServerApplication.class, args);
    }

}

分别启动gds-server、order-server工程，查看效果

 

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原文地址：https://www.cnblogs.com/riches/p/15246368.html