SpringCloud的学习记录(6)

这一章节讲fegin的使用.

在我们生成的Demo项目上右键点击New->Module->spring Initializr, 然后next, 填写Group和Artifact等信息，

这里Artifact填写feginclient, 再次next, 选择内容如下的pom.xml:

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <parent>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-parent</artifactId>

        <version>2.1.3.RELEASE</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

    <groupId>com.xum</groupId>

    <artifactId>feign-client</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>feign-client</name>

    <description>Demo project for Spring Boot</description>

    <properties>

        <java.version>1.8</java.version>

        <spring-cloud.version>Greenwich.RELEASE</spring-cloud.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-starter-openfeign</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</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>

    </dependencies>

    <dependencyManagement>

        <dependencies>

            <dependency>

                <groupId>org.springframework.cloud</groupId>

                <artifactId>spring-cloud-dependencies</artifactId>

                <version>${spring-cloud.version}</version>

                <type>pom</type>

                <scope>import</scope>

            </dependency>

        </dependencies>

    </dependencyManagement>

    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

            </plugin>

        </plugins>

    </build>

    <repositories>

        <repository>

            <id>spring-milestones</id>

            <name>Spring Milestones</name>

            <url>https://repo.spring.io/milestone</url>

        </repository>

    </repositories>

</project>

fegin-client项目结构如下:

1. 首先FeginClientApplication.java里的内容如下:

package com.xum.feignclient;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

import org.springframework.cloud.openfeign.EnableFeignClients;

import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication

@EnableEurekaClient

@EnableFeignClients

@ComponentScan(basePackages = { "com.xum.feignclient.controller", "com.xum.feignclient.server" })

public class FeignClientApplication {

    public static void main(String[] args) {

        SpringApplication.run(FeignClientApplication.class, args);

    }

}

2. application.yml内容如下:

eureka:

  client:

    serviceUrl:

      defaultZone: http://localhost:8761/eureka/

server:

  port: 8772

spring:

  application:

    name: fegin-client

feign:

  hystrix:

    enabled: true

management:

  endpoint:

    health:

      show-details: always

  endpoints:

    web:

      exposure:

        include: '*'

3. 然后FeignConsumerController.java内容如下:

package com.xum.feignclient.controller;

import com.xum.feignclient.server.HelloService;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

@RestController

@RequestMapping(value = "/feign")

public class FeignConsumerController {

    private static final Logger LOG = LoggerFactory.getLogger(FeignConsumerController.class);

    @Autowired

    HelloService helloService;

    @RequestMapping(value = "/feignconsumer")

    public String helloConsumer(){

        LOG.info("FeginConsumerController=>helloConsumer");

        return helloService.hello();

    }

    @RequestMapping(value = "/test")

    public String test() {

        return "test";

    }

}

4. 其次就是HelloService.java接口内容如下:

package com.xum.feignclient.server;

import org.springframework.cloud.openfeign.FeignClient;

import org.springframework.web.bind.annotation.RequestMapping;

// 这里的FeginClient注解, value是说明调用的那个项目,就是spring.application.name对应的名字;

// fallback是调用value项目api失败后, 处理的方法类, 这也是自定义的.

@FeignClient(value = "eureka-client", fallback = HystrixService.class)

public interface HelloService {

    @RequestMapping(value = "/testone/test")

    String hello();

}

5. 然后是HystrixService.java内容如下:

package com.xum.feignclient.server;

import org.springframework.stereotype.Service;

@Service

public class HystrixService implements HelloService {

    // 这里就是当调用api失败后, 对应的处理方法.

    @Override

    public String hello() {

        return " HelloService=>HystrixService=>eureka-client is unable ...";

    }

}

现在启动如下的项目:

1. eureka-server

2. config-server

3. feign-client

4. eureka-client

在浏览器或则post man中输入api：http://localhost:8772/feign/feignconsumer, 显示内容如下:

说明成功调用eureka-client项目里的testone/test这条api.

现在把eureka-client项目停止, 然后再输入这条api: http://localhost:8772/feign/feignconsumer, 内容如下:

现在这里输出的是HystrixService.java里的内容里, 自我保护的机制.

巴特西

SpringCloud的学习记录(6)

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