Spring Cloud Ribbon：负载均衡的服务调用

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Ribbon简介

       简单的说，Ribbon 是 Netflix 发布的开源项目，主要功能是提供客户端的软件负载均衡算法，将 Netflix 的中间层服务连接在一起。Ribbon 客户端组件提供一系列完善的配置项如连接超时，重试等。简单的说，就是在配置文件中列出Load Balancer（简称LB）后面所有的机器，Ribbon 会自动的帮助你基于某种规则（如简单轮询，随机连接等）去连接这些机器。我们也很容易使用 Ribbon 实现自定义的负载均衡算法。

RestTemplate的使用

RestTemplate是一个HTTP客户端，使用它我们可以方便的调用HTTP接口，支持GET、POST、PUT、DELETE等方法。

GET请求方法

T getForObject(String url, Class responseType, Object... uriVariables);

T getForObject(String url, Class responseType, Map uriVariables);

T getForObject(URI url, Class responseType);

ResponseEntitygetForEntity(String url, Class responseType, Object... uriVariables);

ResponseEntitygetForEntity(String url, Class responseType, Map uriVariables);

ResponseEntitygetForEntity(URI var1, Class responseType);

getForObject方法

@GetMapping("/{id}")

public CommonResultgetUser(@PathVariable Long id) {

return restTemplate.getForObject(userServiceUrl +"/user/{1}", CommonResult.class, id);

}

getForEntity方法

//返回对象为ResponseEntity对象，包含了响应中的一些重要信息，比如响应头、响应状态码、响应体等

@GetMapping("/getEntityByUsername")

public CommonResultgetEntityByUsername(@RequestParam String username) {

ResponseEntity entity = restTemplate.getForEntity(userServiceUrl +"/user/getByUsername?username={1}", CommonResult.class, username);

    if (entity.getStatusCode().is2xxSuccessful()) {

return entity.getBody();

    }else {

return new CommonResult("操作失败", 500);

    }

}

POST请求方法

T postForObject(String url, @Nullable Object request, Class responseType, Object... uriVariables);

T postForObject(String url, @Nullable Object request, Class responseType, Map uriVariables);

T postForObject(URI url, @Nullable Object request, Class responseType);

ResponseEntitypostForEntity(String url, @Nullable Object request, Class responseType, Object... uriVariables);

ResponseEntitypostForEntity(String url, @Nullable Object request, Class responseType, Map uriVariables);

ResponseEntitypostForEntity(URI url, @Nullable Object request, Class responseType);

postForObject示例

@PostMapping("/create")

public CommonResultcreate(@RequestBody User user) {

return restTemplate.postForObject(userServiceUrl +"/user/create", user, CommonResult.class);

}

postForEntity示例

@PostMapping("/create")

public CommonResultcreate(@RequestBody User user) {

return restTemplate.postForEntity(userServiceUrl +"/user/create", user, CommonResult.class).getBody();

}

PUT请求方法

void put(String url, @Nullable Object request, Object... uriVariables);

void put(String url, @Nullable Object request, Map uriVariables);

void put(URI url, @Nullable Object request);

PUT请求示例

@PutMapping("/update")

public CommonResultupdate(@RequestBody User user) {

restTemplate.put(userServiceUrl +"/user/update", user);

    return new CommonResult("操作成功",200);

}

DELETE请求方法

void delete(String url, Object... uriVariables);

void delete(String url, Map uriVariables);

void delete(URI url);

DELETE请求示例

@DeleteMapping("/delete/{id}")

public CommonResultdelete(@PathVariable Long id) {

restTemplate.delete(userServiceUrl +"/user/delete/{1}", null, id);

    return new CommonResult("操作成功",200);

}

创建user-service模块

用来给ribbon提供服务，添加依赖

  <groupId>org.springframework.cloud

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

  <groupId>org.springframework.boot

  <artifactId>spring-boot-starter-web

</dependency>

添加配置文件

server:

port:8201

spring:

application:

name: user-service

eureka:

client:

register-with-eureka: true

fetch-registry: true

service-url:

defaultZone: http://localhost:8001/eureka/

添加userController常用接口

package com.macro.cloud.controller;

import com.macro.cloud.domain.CommonResult;

import com.macro.cloud.domain.User;

import com.macro.cloud.service.UserService;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

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

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

import java.util.List;

/**

* Created by danpipi.

*/

@RestController

@RequestMapping("/user")

public class UserController {

private LoggerLOGGER = LoggerFactory.getLogger(this.getClass());

    @Autowired

    private UserServiceuserService;

    @PostMapping("/create")

public CommonResultcreate(@RequestBody User user) {

userService.create(user);

        return new CommonResult("操作成功", 200);

    }

@GetMapping("/{id}")

public CommonResultgetUser(@PathVariable Long id) {

User user =userService.getUser(id);

        LOGGER.info("根据id获取用户信息，用户名称为：{}",user.getUsername());

        return new CommonResult<>(user);

    }

@GetMapping("/getUserByIds")

public CommonResult>getUserByIds(@RequestParam List ids) {

List userList=userService.getUserByIds(ids);

        LOGGER.info("根据ids获取用户信息，用户列表为：{}",userList);

        return new CommonResult<>(userList);

    }

@GetMapping("/getByUsername")

public CommonResultgetByUsername(@RequestParam String username) {

User user =userService.getByUsername(username);

        return new CommonResult<>(user);

    }

@PostMapping("/update")

public CommonResultupdate(@RequestBody User user) {

userService.update(user);

        return new CommonResult("操作成功", 200);

    }

@PostMapping("/delete/{id}")

public CommonResultdelete(@PathVariable Long id) {

userService.delete(id);

        return new CommonResult("操作成功", 200);

    }

}

创建ribbon-service模块，调用user-service模块实现负载均衡，添加依赖

  <groupId>org.springframework.boot

  <artifactId>spring-boot-starter-web

  <groupId>org.springframework.cloud

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

  <groupId>org.springframework.cloud

  <artifactId>spring-cloud-starter-netflix-ribbon

</dependency>

配置文件

server:

port:8301

spring:

application:

name: ribbon-serviceeureka:

client:

register-with-eureka:true

    fetch-registry:true

    service-url:

defaultZone: http://localhost:8001/eureka/

service-url:

user-service: http://user-service

@LoadBalanced注解可以提供RestTemplate负载均衡

package com.macro.cloud.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.web.client.RestTemplate;

/**

* Created by 蛋皮皮 on 2020/8/29.

*/

@Configuration

public class RibbonConfig {

@Bean

@LoadBalanced

    public RestTemplaterestTemplate(){

return new RestTemplate();

    }

}

UserRibbonController

package com.macro.cloud.controller;

import com.macro.cloud.domain.CommonResult;

import com.macro.cloud.domain.User;

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

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

import org.springframework.http.ResponseEntity;

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

import org.springframework.web.client.RestTemplate;

/**

* Created by 蛋皮皮 on 2020/8/29.

*/

@RestController

@RequestMapping("/user")

public class UserRibbonController {

@Autowired

    private RestTemplaterestTemplate;

    @Value("${service-url.user-service}")

private StringuserServiceUrl;

    @GetMapping("/{id}")

public CommonResultgetUser(@PathVariable Long id) {

return restTemplate.getForObject(userServiceUrl +"/user/{1}", CommonResult.class, id);

    }

@GetMapping("/getByUsername")

public CommonResultgetByUsername(@RequestParam String username) {

return restTemplate.getForObject(userServiceUrl +"/user/getByUsername?username={1}", CommonResult.class, username);

    }

@GetMapping("/getEntityByUsername")

public CommonResultgetEntityByUsername(@RequestParam String username) {

ResponseEntity entity =restTemplate.getForEntity(userServiceUrl +"/user/getByUsername?username={1}", CommonResult.class, username);

        if (entity.getStatusCode().is2xxSuccessful()) {

return entity.getBody();

        }else {

return new CommonResult("操作失败", 500);

        }

}

@PostMapping("/create")

public CommonResultcreate(@RequestBody User user) {

return restTemplate.postForObject(userServiceUrl +"/user/create", user, CommonResult.class);

    }

@PostMapping("/update")

public CommonResultupdate(@RequestBody User user) {

return restTemplate.postForObject(userServiceUrl +"/user/update", user, CommonResult.class);

    }

@PostMapping("/delete/{id}")

public CommonResultdelete(@PathVariable Long id) {

return restTemplate.postForObject(userServiceUrl +"/user/delete/{1}", null, CommonResult.class, id);

    }

}

启动后调用接口测试http://localhost:8301/user/1

Ribbon的常用配置

#全局配置

ribbon:

ConnectTimeout: 1000 #服务请求连接超时时间（毫秒）

ReadTimeout: 3000 #服务请求处理超时时间（毫秒）

OkToRetryOnAllOperations: true #对超时请求启用重试机制

MaxAutoRetriesNextServer: 1 #切换重试实例的最大个数

MaxAutoRetries: 1 #切换实例后重试最大次数

NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule #修改负载均衡算法

指定服务配置

user-service:

ribbon:

ConnectTimeout: 1000 #服务请求连接超时时间（毫秒）

  ReadTimeout: 3000 #服务请求处理超时时间（毫秒）

  OkToRetryOnAllOperations: true #对超时请求启用重试机制

  MaxAutoRetriesNextServer: 1 #切换重试实例的最大个数

  MaxAutoRetries: 1 #切换实例后重试最大次数

  NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule #修改负载均衡算法

使用到的模块

springcloud-learning

├── eureka-server -- eureka注册中心

├── user-service --提供User对象CRUD接口的服务

└── ribbon-service -- ribbon服务调用测试服务