SpringClub03-ribbon负载均衡和重试

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小韩
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    一、ribbon 服务消费者

    ribbon 提供了负载均衡和重试功能, 它底层是使用 RestTemplate 进行 Rest api 调用

    1.RestTemplate

    RestTemplate 是SpringBoot提供的一个Rest远程调用工具
    它的常用方法:

    • getForObject() - 执行get请求
    • postForObject() - 执行post请求

    之前的系统结构是浏览器直接访问后台服务
    直接访问
    后面我们通过一个Demo项目演示 Spring Cloud 远程调用
    Demo
    下面我们先不使用ribbon, 单独使用RestTemplate来执行远程调用

    1.1 新建 sp06-ribbon 项目

    image.png

    1.2 修改pom文件

    • eureka-client 中已经包含 ribbon 依赖
    • 需要添加 sp01-commons 依赖
    <?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>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cn.tedu</groupId>
    <artifactId>sp06-ribbon</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>sp06-ribbon</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.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.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>cn.tedu</groupId>
            <artifactId>sp01-commons</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </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>
</project>

    1.3 修改application.yml

    spring:
  application:
    name: ribbon
    
server:
  port: 3001
  
eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka

    1.4 主程序

    • 创建 RestTemplate 实例
      RestTemplate 是用来调用其他微服务的工具类，封装了远程调用代码，提供了一组用于远程调用的模板方法，例如：getForObject()、postForObject() 等
    package cn.tedu.sp06;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@EnableDiscoveryClient
@SpringBootApplication
public class Sp06RibbonApplication {
    //创建 RestTemplate 实例，并存入 spring 容器
    @Bean
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(Sp06RibbonApplication.class, args);
    }
}

    1.5 创建 RibbonController 类

    package com.tedu.sp06.controller;
import cn.tedu.sp01.pojo.Item;
import cn.tedu.sp01.pojo.Order;
import cn.tedu.sp01.pojo.User;
import cn.tedu.web.util.JsonResult;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;
import java.util.List;
@RestController
@Slf4j
public class RibbonController {
    @Autowired
 private RestTemplate rt;
    @GetMapping("/item-service/{orderId}")
    public JsonResult<List<Item>> getItems(@PathVariable String orderId) {
        // 调用远程的商品服务，获得订单的商品列表
 // {1} - RestTemplate自己定义的一种站位符格式
 return rt.getForObject("http://localhost:8001/{1}",
                JsonResult.class,
                orderId); //用 orderId 填充占位符 {1} }
    @PostMapping("/item-service/decreaseNumber")
    public JsonResult<?> decreaseNumber(@RequestBody List<Item> items) {
        return rt.postForObject(
                "http://localhost:8001/decreaseNumber",
                items,
                JsonResult.class);
    }
    @GetMapping("/user-service/{userId}")
    public JsonResult<User> getUser(@PathVariable Integer userId) {
        return rt.getForObject("http://localhost:8101/{1}",
                JsonResult.class,
                userId);
    }
    @GetMapping("/user-service/{userId}/score") //    ?score=1000
 public JsonResult<?> addScore(@PathVariable Integer userId,
                                  @RequestParam Integer score) {
        return rt.getForObject("http://localhost:8101/{1}/score?score={2}",
                JsonResult.class,
                userId, score);
    }
    @GetMapping("/order-service/{orderId}")
    public JsonResult<Order> getOrder(@PathVariable String orderId) {
        return rt.getForObject("http://localhost:8201/{1}",
                JsonResult.class,
                orderId);
    }
    @GetMapping("/order-service/")
    public JsonResult<?> addOrder() {
        return rt.getForObject("http://localhost:8201/",JsonResult.class);
    }
}

    1.6 启动服务，并访问测试

    image.png
    http://eureka1:2001
    http://localhost:3001/item-service/35
    http://localhost:3001/item-service/decreaseNumber
    使用postman，POST发送以下格式数据：
    [{"id":1, "name":"abc", "number":23},{"id":2, "name":"def", "number":11}]
    http://localhost:3001/user-service/7
    http://localhost:3001/user-service/7/score?score=100
    http://localhost:3001/order-service/123abc
    http://localhost:3001/order-service/

    2. ribbon 负载均衡和重试

    image.png

    2.1 Ribbon 负载均衡

    image.png

    2.1.1 添加 ribbon 依赖

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

    2.1.2 RestTemplate 设置 @LoadBalanced

    @LoadBalanced 负载均衡注解，会对 RestTemplate 实例进行封装，创建动态代理对象，并切入（AOP）负载均衡代码，把请求分发到集群中的服务器

    package cn.tedu.sp06;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@EnableDiscoveryClient
@SpringBootApplication
public class Sp06RibbonApplication {
    @LoadBalanced //负载均衡注解
    @Bean
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(Sp06RibbonApplication.class, args);
    }
}

    2.1.3 访问路径设置为服务id

    package cn.tedu.sp06.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import cn.tedu.sp01.pojo.Item;
import cn.tedu.sp01.pojo.Order;
import cn.tedu.sp01.pojo.User;
import cn.tedu.web.util.JsonResult;
@RestController
public class RibbonController {
    @Autowired
    private RestTemplate rt;
    @GetMapping("/item-service/{orderId}")
@HystrixCommand(fallbackMethod = "getItemsFB")
public JsonResult<List<Item>> getItems(@PathVariable String orderId) {
    //调用远程的商品服务，获得订单的商品列表
    //{1} - RestTemplate自己定义的一种站位符格式
@PostMapping("/item-service/decreaseNumber")
public JsonResult<?> decreaseNumber(@RequestBody List<Item> items) {
    return rt.postForObject("http://item-service/decreaseNumber", items, JsonResult.class);
}
@GetMapping("/user-service/{userId}")
public JsonResult<User> getUser(@PathVariable Integer userId) {
    return rt.getForObject("http://user-service/{1}", JsonResult.class, userId);
}
@GetMapping("/user-service/{userId}/score") // ?score=1000
public JsonResult<?> addScore(@PathVariable Integer userId, @RequestParam Integer score) {
    return rt.getForObject("http://user-service/{1}/score?score={2}", JsonResult.class, userId, score);
}
@GetMapping("/order-service/{orderId}")
public JsonResult<Order> getOrder(@PathVariable String orderId) {
    return rt.getForObject("http://order-service/{1}", JsonResult.class, orderId);
}
@GetMapping("/order-service")
public JsonResult<?> addOrder() {
    return rt.getForObject("http://order-service", JsonResult.class);
}

    2.1.4 访问测试

    访问测试
    访问测试

    2.2 ribbon 重试

    image.png

    2.2.1 添加 ribbon 依赖

    <dependency>
    <groupId>org.springframework.retry</groupId>
    <artifactId>spring-retry</artifactId>
</dependency>

    2.2.2 配置 application.yml

    spring:
  application:
    name: ribbon   
server:
  port: 3001
#连接eureka
eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka
ribbon:
  #单台重试次数
 MaxAutoRetries: 1
  #更换服务器次数
 MaxAutoRetriesNextServer: 2

    2.2.3 主程序设置 RestTemplate 的请求工厂的超时属性

    package com.tedu.sp06;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
@EnableCircuitBreaker//启用断路器
public class Sp06RibbonApplication {
   public static void main(String[] args) {
      SpringApplication.run(Sp06RibbonApplication.class, args);
   }
   //创建 RestTemplate 实例，并存入 spring 容器
 @LoadBalanced//负载均衡注解,对 RestTemplate 进行封装,增强RestTemplate的功能
 @Bean
 public RestTemplate getRestTemplate (){
      SimpleClientHttpRequestFactory f=new SimpleClientHttpRequestFactory();
      //两个超时参数默认-1，表示不启用
 f.setConnectTimeout(1000);
      f.setReadTimeout(1000);
      return new RestTemplate();
}
}

    2.2.4 ItemController 添加延迟代码，以便测试 ribbon 的重试机制

    package cn.tedu.sp02.item.controller;
import cn.tedu.sp01.pojo.Item;
import cn.tedu.sp01.service.ItemService;
import cn.tedu.web.util.JsonResult;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;
import java.util.List;
import java.util.Random;
@RestController
@Slf4j
public class ItemController {
    @Autowired
 private ItemService itemService;
    // 为了后面测试集群多台服务器，这里注入端口号
 @Value("${server.port}")
    private int port;
    @GetMapping("/{orderId}")
    public JsonResult<List<Item>> getItems(@PathVariable String orderId) throws InterruptedException {
        log.info("orderId="+orderId+", port="+port);
        //添加随机延迟代码
        if (Math.random()<0.9){
        //随机产生0到5000的随机延迟时长
            long t=new Random().nextInt(5000);
            log.info("延迟:"+t);
            Thread.sleep(t);
        }
       //
        List<Item> items = itemService.getItems(orderId);
        return JsonResult.ok().msg("port="+port).data(items);
    }
    // 只处理post请求
 // @RequestBody 注解，完整接收post请求协议体数据
 @PostMapping("/decreaseNumber")
    public JsonResult<?> decreaseNumber(@RequestBody List<Item> items) {
        itemService.decreaseNumber(items);
        return JsonResult.ok().msg("减少商品库存成功");
    }
}

    2.2.5 测试 ribbon 重试机制

    重试测试
    重试测试

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