Feign负载均衡

简介

客户端集成Feign

pom文件

  <!--Feign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>

DeptClientService调用文件

@FeignClient(value = "SPRINGCLOUD-PROVIDER-DEPT")
public interface DeptClientService {

    @GetMapping("/dept/{deptNo}")
    Dept queryByDeptNo(@PathVariable("deptNo") Long deptNo);

    @GetMapping("/dept/queryAll")
    List<Dept> queryAll();

    @PostMapping("/dept/add")
    boolean addDept(@RequestBody Dept dept);
}

客户端调用

@RestController
public class FeignController {

    @Autowired
    private DeptClientService clientService;

    @GetMapping("/consumer/dept/{deptNo}")
    public Dept get(@PathVariable("deptNo") Long deptNo){
        return clientService.queryByDeptNo(deptNo);
    }

    @GetMapping("/consumer/list")
    public List<Dept> queryAll(){
        return clientService.queryAll();
    }

    @PostMapping("/consumer/dept/add")
    public boolean add(@RequestBody Dept dept){
        return clientService.addDept(dept);
    }
}

客户端启动类
添加注解：@EnableFeignClients(basePackages = {"com.service"})

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients(basePackages = {"com.service"})
public class FeignApplication {
    public static void main(String[] args) {
        SpringApplication.run(FeignApplication.class,args);
    }
}

Hystrix

分布式系统面临的问题

复杂分布式体系结构中的应用程序十分依赖关系，每个依赖关系在某些时候将不可避免的失败！

服务雪崩

Hystrix定义

服务熔断

在这里插入图片描述

服务端集成Hystrix(springcloud-provider-dept-hystrix)实现服务熔断

pom.xml

 <dependencies>
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>springcloud-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>com.fasterxml.jackson.dataformat</groupId>
                    <artifactId>jackson-dataformat-xml</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--完善监控信息-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <!--hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
            <version>1.4.6.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>2.0.5</version>
        </dependency>
    </dependencies>

yml文件

server:
  port: 8002
#mybatis配置
mybatis:
  type-aliases-package: com.api.model
  mapper-locations: classpath:mybatis/mapper/*.xml
  config-location: classpath:mybatis/mybatis-config.xml
#spring配置
spring:
  application:
    name: springcloud-provider-dept
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: org.gjt.mm.mysql.Driver
    url: jdbc:mysql://localhost:3306/iwmstest?useUnicode=true&characterEncoding=UTF-8
    username: root
    password: 123456

#Eureka配置，服务注册到哪里
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    instance-id: springcloud-server-provider-hystrix-8002 #修改Eureka的默认描述信息

#info配置
info:
  app.name: zzq-springcloud
  company.name: blog.com

controller配置
加注解：@HystrixCommand(fallbackMethod = "hystrixGet")

@RestController
public class DeptHystrixController {

    @Autowired
    private DeptHystrixService deptService;

    @HystrixCommand(fallbackMethod = "hystrixGet")
    @GetMapping("/dept/{deptNo}")
    public Dept get(@PathVariable("deptNo") Long deptNo){
        Dept dept = deptService.queryById(deptNo);
        if (dept == null) {
            throw new RuntimeException("不存在该用户");
        }
        return dept;
    }

    //备选方法
    public Dept hystrixGet(Long deptNo){
        return new Dept()
                .setDeptNo(deptNo)
                .setDName("没有用户")
                .setDbSource("no database");
    }
}

启动类开启熔断机制
@EnableCircuitBreaker //启动服务熔断

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker //启动服务熔断
public class HystrixApplicaiton {
    public static void main(String[] args) {
        SpringApplication.run(HystrixApplicaiton.class,args);
    }
}

客户端集成Hystrix实现服务降级

DeptClientServiceFailBackFactory.java

@Component
public class DeptClientServiceFailBackFactory implements FallbackFactory<DeptClientService> {
    @Override
    public DeptClientService create(Throwable throwable) {
        return new DeptClientService() {
            @Override
            public Dept queryByDeptNo(Long deptNo) {
                return new Dept().setDeptNo(deptNo)
                        .setDName("没有对应的信息")
                        .setDbSource("no database")
                        ;
            }
            @Override
            public List<Dept> queryAll() {
                return null;
            }

            @Override
            public boolean addDept(Dept dept) {
                return false;
            }
        };
    }
}

DeptClientService.java
添加：fallbackFactory = DeptClientServiceFailBackFactory.class

@FeignClient(value = "SPRINGCLOUD-PROVIDER-DEPT",fallbackFactory = DeptClientServiceFailBackFactory.class)
public interface DeptClientService {

    @GetMapping("/dept/{deptNo}")
    Dept queryByDeptNo(@PathVariable("deptNo") Long deptNo);

    @GetMapping("/dept/queryAll")
    List<Dept> queryAll();

    @PostMapping("/dept/add")
    boolean addDept(@RequestBody Dept dept);
}

客户端配置文件开启服务降级
开启服务降级 feign: hystrix: enabled: true

server:
  port: 8081


#Eureka配置
eureka:
  client:
    register-with-eureka: false #不向Eureka注册自己
    service-url:
      defaultZone: http://localhost:8761/eureka/ #客户端注册进Eureka

# 开启服务降级
feign:
  hystrix:
    enabled: true