【分散式】-- 基於Nacos、OpenFeign搭建的微服務抽獎系統後臺小案例

1.專案介紹

最近入專案之前要求熟悉一下SpringCloud Nacos微服務基於Feign介面呼叫並整合Swagger2進行介面文件展示給前端，所以自己按照要求來編寫並整合了一套基於SpringCloudAlibaba Nacos、Feign、MyBatis、Swagger2的簡單微服務抽獎系統，並結合資料庫資料進行資料返回。

框架提供了基礎的微服務註冊與發現，介面Swagger訪問、MyBatis註解實現介面Dao層資料訪問，可用於快速搭建一個微服務CRUD基礎框架。

抽獎介面主要包含：新增商品介面（包含商品名稱和中獎率）；抽獎介面，對新增的商品進行抽獎返回中獎商品的功能。

1.1.專案框架搭建

①專案主要結構說明：

common-api模組：用於存放公共的pojo類、介面返回值列舉類、公共的抽獎函式
consumer-product7800模組：服務消費方
provider-product6700模組：服務提供方

②pom.xml依賴說明：

父工程主要pom依賴包：

其中主要的pom依賴有

spring-cloud-alibaba-dependencies

mybatis-spring-boot-starter

lombok

springfox-swagger2

swagger-bootstrap-ui

    <!--統一管理jar包版本-->

    <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

        <maven.compiler.source>1.8</maven.compiler.source>

        <maven.compiler.target>1.8</maven.compiler.target>

        <junit.version>4.12</junit.version>

        <springboot.test.version>2.5.0</springboot.test.version>

        <log4j.version>1.2.17</log4j.version>

        <lombok.version>1.16.18</lombok.version>

        <mysql.version>6.0.6</mysql.version>

        <druid.version>1.1.16</druid.version>

        <mybatis.spring.boot.version>2.1.4</mybatis.spring.boot.version>

        <springboot.starter.web>2.4.3</springboot.starter.web>

    </properties>

    <!--子模組繼承之後，提供作用：鎖定版本+子module不用寫groupId和version-->

    <dependencyManagement>

    <dependencies>

        <!--spring boot 2.2.2-->

        <dependency>

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

            <artifactId>spring-boot-dependencies</artifactId>

            <version>2.2.2.RELEASE</version>

            <type>pom</type>

            <scope>import</scope>

        </dependency>

        <!--springcloud Hoxton.SR1-->

        <dependency>

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

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

            <version>Hoxton.SR1</version>

            <type>pom</type>

            <scope>import</scope>

        </dependency>

        <!--springcloud alibaba 2.1.0.RELEASE-->

        <dependency>

            <groupId>com.alibaba.cloud</groupId>

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

            <version>2.1.0.RELEASE</version>

            <type>pom</type>

            <scope>import</scope>

        </dependency>

        <!--mysql資料庫連線驅動包-->

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <version>${mysql.version}</version>

        </dependency>

        <!--web依賴包-->

        <dependency>

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

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

            <version>${springboot.starter.web}</version>

        </dependency>

        <!--alibaba druid資料庫-->

        <dependency>

            <groupId>com.alibaba</groupId>

            <artifactId>druid</artifactId>

            <version>${druid.version}</version>

        </dependency>

        <!--mybatis orm框架-->

        <dependency>

            <groupId>org.mybatis.spring.boot</groupId>

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

            <version>${mybatis.spring.boot.version}</version>

        </dependency>

        <!--lombok外掛引入-->

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <version>${lombok.version}</version>

        </dependency>

        <!--熱啟動部署-->

        <dependency>

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

            <artifactId>spring-boot-devtools</artifactId>

            <version>2.1.10.RELEASE</version>

            <scope>runtime</scope>

            <optional>true</optional>

        </dependency>

        <!--測試依賴包引入-->

        <dependency>

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

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

            <version>${springboot.test.version}</version>

            <scope>test</scope>

        </dependency>

        <!--log4j日誌包-->

        <dependency>

            <groupId>org.apache.logging.log4j</groupId>

            <artifactId>log4j</artifactId>

            <version>${log4j.version}</version>

        </dependency>

        <!--swagger2依賴-->

        <dependency>

            <groupId>io.springfox</groupId>

            <artifactId>springfox-swagger2</artifactId>

            <version>2.7.0</version>

        </dependency>

        <!--swagger第三方ui依賴-->

        <dependency>

            <groupId>com.github.xiaoymin</groupId>

            <artifactId>swagger-bootstrap-ui</artifactId>

            <version>1.9.6</version>

        </dependency>

    </dependencies>

    </dependencyManagement>

    <build>

        <plugins>

            <plugin>

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

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

                <configuration>

                    <!--排除lombok jar在打包編譯期間-->

                    <excludes>

                        <exclude>

                            <groupId>org.projectlombok</groupId>

                            <artifactId>lombok</artifactId>

                        </exclude>

                    </excludes>

                </configuration>

            </plugin>

            <!--引入mybatis逆向工程外掛-->

            <plugin>

                <groupId>org.mybatis.generator</groupId>

                <artifactId>mybatis-generator-maven-plugin</artifactId>

                <version>1.3.5</version>

                <configuration>

                    <configurationFile>${basedir}/src/main/resources/mybatis-generator/generatorConfig.xml

                    </configurationFile>

                    <overwrite>true</overwrite>

                    <verbose>true</verbose>

                </configuration>

            </plugin>

        </plugins>

    </build>

springcloudnacos-provider-product6700

 <dependencies>

        <!--SpringCloud alibaba nacos-->

        <dependency>

            <groupId>com.alibaba.cloud</groupId>

            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>

        </dependency>

        <!--SpringBoot整合Web元件-->

        <dependency>

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

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

        </dependency>

        <!--服務註冊與發現-->

        <dependency>

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

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

        </dependency>

        <!--日常通用jar包配置-->

        <dependency>

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

            <artifactId>spring-boot-devtools</artifactId>

            <scope>runtime</scope>

            <optional>true</optional>

        </dependency>

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <optional>true</optional>

        </dependency>

        <!--api jar包引入-->

        <dependency>

            <groupId>com.fengye</groupId>

            <artifactId>springcloudnacos-common-api</artifactId>

            <version>0.0.1-SNAPSHOT</version>

        </dependency>

        <!--集合判空工具類-->

        <dependency>

            <groupId>org.apache.commons</groupId>

            <artifactId>commons-collections4</artifactId>

            <version>4.3</version>

        </dependency>

        <!--引入Swagger2元件-->

        <dependency>

            <groupId>io.springfox</groupId>

            <artifactId>springfox-swagger2</artifactId>

            <version>2.9.2</version>

        </dependency>

        <!--mysql連線驅動包-->

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

        </dependency>

        <!--mybatis-->

        <dependency>

            <groupId>org.mybatis.spring.boot</groupId>

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

        </dependency>

        <!--引入ui包-->

        <dependency>

            <groupId>io.springfox</groupId>

            <artifactId>springfox-swagger2</artifactId>

            <version>2.7.0</version>

        </dependency>

        <!--swagger第三方ui依賴-->

        <dependency>

            <groupId>com.github.xiaoymin</groupId>

            <artifactId>swagger-bootstrap-ui</artifactId>

            <version>1.9.6</version>

        </dependency>

    </dependencies>

springcloudnacos-consumer-product7800

 <dependencies>

        <!--springcloud openfeign-->

        <dependency>

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

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

        </dependency>

        <!--sentinel熔斷限流-->

        <dependency>

            <groupId>com.alibaba.cloud</groupId>

            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>

        </dependency>

        <!--SpringCloud alibaba nacos-->

        <dependency>

            <groupId>com.alibaba.cloud</groupId>

            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>

        </dependency>

        <!--引入自定義的api通用包-->

        <dependency>

            <groupId>com.fengye</groupId>

            <artifactId>springcloudnacos-common-api</artifactId>

            <version>0.0.1-SNAPSHOT</version>

        </dependency>

        <!--SpringBoot整合Web元件-->

        <dependency>

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

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

        </dependency>

        <dependency>

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

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

        </dependency>

        <!--日常通用jar包配置-->

        <dependency>

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

            <artifactId>spring-boot-devtools</artifactId>

            <scope>runtime</scope>

            <optional>true</optional>

        </dependency>

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <optional>true</optional>

        </dependency>

        <dependency>

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

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

            <scope>test</scope>

        </dependency>

        <!--引入Swagger2元件-->

        <dependency>

            <groupId>io.springfox</groupId>

            <artifactId>springfox-swagger2</artifactId>

            <version>2.9.2</version>

        </dependency>

        <!--引入ui包-->

        <dependency>

            <groupId>io.springfox</groupId>

            <artifactId>springfox-swagger2</artifactId>

            <version>2.7.0</version>

        </dependency>

        <!--swagger第三方ui依賴-->

        <dependency>

            <groupId>com.github.xiaoymin</groupId>

            <artifactId>swagger-bootstrap-ui</artifactId>

            <version>1.9.6</version>

        </dependency>

        <dependency>

            <groupId>org.apache.commons</groupId>

            <artifactId>commons-collections4</artifactId>

            <version>4.3</version>

        </dependency>

    </dependencies>

③application.yml配置

重點主要是在服務生產方provider-product6700進行資料庫連線、mybatis框架、nacos服務註冊相關的配置，具體如下：

server:

  port: 6700

spring:

  application:

    name: nacos-product-provider-6700

  cloud:

    nacos:

      discovery:

        server-addr: localhost:8848

  #資料庫連線池配置

  datasource:

    username: root

    password: admin

    #假如時區報錯，增加時區配置serverTimezone=UTC

    url: jdbc:mysql://localhost:3306/nacosproduct?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8

    driver-class-name: com.mysql.cj.jdbc.Driver

#整合mybatis配置

mybatis:

  #config-location: classpath:mybatis/mybatis-config.xml  使用了configuration註解則無需再指定mybatis-config.xml檔案

  mapper-locations: classpath:mybatis/mapper/*.xml

  configuration:   #指定mybatis全域性配置檔案中的相關配置項

    map-underscore-to-camel-case: true

  type-aliases-package: com.fengye.springcloud.entities

#消費者將要去訪問的微服務名稱

server-url:

  nacos-user-service: http://nacos-product-provider

1.2.專案分包結構說明

以一個服務提供方6700來說，就是簡單地controller、mapper、service/impl，mapper層使用xml與註解結合的方式都可以。這裡不再多說。

而在服務消費方7800來說，主要分為Feign介面呼叫與Swagger2Config配置類：

2.Swagger2/Feign介面/抽獎介面說明

2.1.Swagger2配置類

①這裡主要的就是在專案中會引入Swagger2的依賴包，以及基於國人UI風格的jar包。

  <!--引入Swagger2元件-->

  <dependency>

          <groupId>io.springfox</groupId>

          <artifactId>springfox-swagger2</artifactId>

          <version>2.9.2</version>

  </dependency>

  <!--swagger第三方ui依賴-->

  <dependency>

      <groupId>com.github.xiaoymin</groupId>

      <artifactId>swagger-bootstrap-ui</artifactId>

      <version>1.9.6</version>

  </dependency>

②編寫Swagger2Config配置類：

//將此類交給Spring管理，表示一個配置類

@Configuration

//開啟Swagger2

@EnableSwagger2

public class Swagger2Config {

    /**

     * 建立API應用

     * apiInfo() 增加API相關資訊

     * 通過select()函式返回一個ApiSelectorBuilder例項,用來控制哪些介面暴露給Swagger來展現，

     * 本例採用指定掃描的包路徑來定義指定要建立API的目錄

     *

     * @return 返回Swagger的Docket配置Bean例項

     */

    @Bean

    public Docket createRestApi(Environment environment) {

        return new Docket(DocumentationType.SWAGGER_2)

                .apiInfo(apiInfo())

                .enable(true)  //enable是否啟動swagger，如果為False，則swagger不能在瀏覽器中訪問

                .select()

                //指定API物件掃描哪個包下面的controller

                //引數any()：掃描全部； none()：都不掃描

                //withClassAnnotation：掃描類上的註解，引數是一個註解的反射物件

                //withMethodAnnotation：掃描方法上的註解

                .apis(RequestHandlerSelectors.basePackage("com.fengye.springcloud"))

                //過濾什麼路徑

                .paths(PathSelectors.any())

                .build();

    }

    /**

     * 建立該API的基本資訊（這些基本資訊會展現在文件頁面中）

     * 訪問地址：http://專案實際地址/swagger-ui.html

     * @return  返回API基本資訊

     */

    private ApiInfo apiInfo() {

        return new ApiInfoBuilder()

                //Swagger2展示介面的標題（重要）

                .title("抽獎介面API文件")

                //描述資訊（主要）

                .description("抽獎介面API文件")

                .version("1.0")

                //.termsOfServiceUrl("https://swagger.io/docs")

                //.license("Apache 2.0")

                //.licenseUrl("http://www.apache.org/licenses/LICENSE-2.0")

                //作者資訊

                .contact(new Contact("fengye", "https://www.cnblogs.com/yif0118/",

                        "[email protected]"))

                .build();

    }

}

啟動整體的專案之後，訪問：http://localhost:7800/doc.html，即可看到具體的UI風格的API文件介面：

2.2.Feign介面請求

Feign的介面請求呼叫方式主要是基於服務提供方的Controller介面，並在服務消費方編寫一個基於Controller介面一樣的Service介面層，根據服務名及對應一致的方法名進行呼叫。

springcloudnacos-provider-product6700

服務提供方Controller介面：

@RestController

@Slf4j

public class ProductController {

    @Autowired

    private ProductService productService;

    /**

     * 測試Nacos資料介面

     *

     * @return

     */

    @GetMapping(value = "/provider/test")

    public CommonResult<Product> getProductTest() {

        CommonResult<Product> result = new CommonResult<>();

        result.setCode(ResultCodeEnum.SUCCESS.getCode());

        result.setData(new Product(1, "iphone12Max", (float) 0.05));

        result.setException(null);

        result.setMsg("測試資料介面");

        result.setUrl(null);

        result.setSuccess(true);

        return result;

    }

    /**

     * 根據id查詢商品返回商品介面

     *

     * @param id

     * @return

     */

    @GetMapping(value = "/provider/product/{id}")

    public CommonResult<Product> getProductById(@PathVariable("id") Integer id) {

        Product product = productService.getProductById(id);

        if (product != null) {

            return new CommonResult<Product>(

                ResultCodeEnum.SUCCESS.getCode(),

                product,

                null,

                "根據id查詢商品資訊成功！商品名稱為：" + product,

                true,

                null);

        }

        return new CommonResult<Product>(

            ResultCodeEnum.DATA_NOT_FOUND.getCode(),

            null,

            null,

            "根據id查詢商品資訊失敗！",

            false,

            null);

    }

    /**

     * 獲取所有商品

     *

     * @return

     */

    @GetMapping(value = "/provider/getAll")

    public CommonResult<List<Product>> getAllProducts() {

        List<Product> productList = productService.getProductList();

        if (CollectionUtils.isEmpty(productList)) {

            return new CommonResult<>(

                ResultCodeEnum.DATA_NOT_FOUND.getCode(),

                null,

                null,

                "查詢商品列表資訊失敗！",

                false,

                null

            );

        }

        return new CommonResult<>(

            ResultCodeEnum.SUCCESS.getCode(),

            productList,

            null,

            "查詢商品資訊成功，所得到的的商品列表為：" + productList,

            true,

            null

        );

    }

    /**

     * 新增商品介面：使用Product引數進行JSON資料插入傳遞引數

     *

     * @param product

     * @return

     */

    @PostMapping(value = "/provider/insert")

    public Integer insertProduct(@RequestBody Product product) {

        return productService.insertProduct(product);

    }

    /**

     * 抽獎介面：根據抽獎次數及抽獎商品的概率進行返回抽中的商品

     *

     * @return

     */

    @GetMapping(value = "/provider/luckyDraw")

    public CommonResult<Product> luckyDrawProduct() {

        List<Product> productList = productService.getProductList();

        Product product = LotteryUtil.luckyDraw(productList);

        if (product == null) {

            return new CommonResult<>(

                ResultCodeEnum.PARAMS_NULL.getCode(),

                null,

                null,

                "未抽取到商品，謝謝惠顧！",

                false,

                null

            );

        }

        return new CommonResult<>(

            ResultCodeEnum.SUCCESS.getCode(),

            product,

            null,

            "抽獎商品獲取成功！抽到的商品名稱為：" + product.getProductName(),

            true,

            null

        );

    }

}

springcloudnacos-consumer-product7800

服務消費方Servcie Feign介面：

@Component

@FeignClient(value = "nacos-product-provider-6700")

public interface ProductFeignService {

    //測試整合Nacos服務介面

    @GetMapping(value = "/provider/test")

    public CommonResult<Product> getProductTest();

    //介面名與url地址與服務生產者介面名稱相同

    @GetMapping(value = "/provider/product/{id}")

    public CommonResult<Product> getProductById(@PathVariable("id") Integer id);

    //獲取所有的商品資料

    @GetMapping(value = "/provider/getAll")

    public CommonResult<List<Product>> getAllProducts();

    //編寫一個新增商品介面:包含商品名稱和中獎率

    @PostMapping(value = "/provider/insert")

    public CommonResult<Product> insertProduct(@RequestBody Product product);

    //編寫一個抽獎介面,對新增的商口進行抽獎返回中獎商品

    @GetMapping(value = "/provider/luckyDraw")

    public CommonResult<Product> luckyDrawProduct();

}

暴露給Swagger2訪問的Controller外部介面：

@RestController

@Api(value = "抽獎介面演示",description = "SpringCloud Nacos測試API介面")

public class ProductConsumerController {

    @Value("${server.port}")

    private String serverPort;

    @Autowired

    private ProductFeignService productFeignService;

    @ApiOperation(value = "獲取所有抽獎商品資訊", notes = "獲取所有抽獎商品getAllProducts介面")

    @GetMapping(value = "/consumer/getAll")

    public CommonResult<List<Product>> getAllProducts(){

        CommonResult<List<Product>> allProducts = productFeignService.getAllProducts();

        String requestUrl = String.format("http://localhost:%s/consumer/getAll", serverPort);

        allProducts.setUrl(requestUrl);

        return allProducts;

    }

    @ApiOperation(value = "獲取商品測試test介面", notes = "test介面")

    @GetMapping(value = "/test")

    public CommonResult<Product> getProductTest(){

        CommonResult<Product> productTest = productFeignService.getProductTest();

        String requestUrl = String.format("http://localhost:%s/test", serverPort);

        productTest.setUrl(requestUrl);

        return productTest;

    }

    @RequestMapping(value = "/consumer/getProductById/{id}")

    @ApiOperation(value = "獲取對應id商品介面", notes = "根據商品id獲取商品資訊")

    @ApiImplicitParams({

            @ApiImplicitParam(paramType="query", name = "id", value = "商品id", required = true, dataType = "Integer"),

    })

    public CommonResult<Product> getProductById(@PathVariable("id") Integer id){

        CommonResult<Product> productRes = productFeignService.getProductById(id);

        String requestUrl = String.format("http://localhost:%s/consumer/getProductById/%s", serverPort, id);

        productRes.setUrl(requestUrl);

        return productRes;

    }

    @PostMapping(value = "/consumer/insert")

    @ApiOperation(value = "插入抽獎商品insert介面", notes = "插入商品介面，包含商品資訊、商品抽獎概率")

    @ApiImplicitParams({

            @ApiImplicitParam(paramType="insert", name = "id", value = "商品", required = true, dataType = "Product"),

    })

    public CommonResult<Product> insertProduct(@RequestBody Product product){

        CommonResult<Product> result = productFeignService.insertProduct(product);

        String requestUrl = String.format("http://localhost:%s//consumer/insert", serverPort);

        result.setUrl(requestUrl);

        return result;

    }

    //編寫一個抽獎介面,對新增的商口進行抽獎返回中獎商品

    @GetMapping(value = "/consumer/luckyDraw")

    @ApiOperation(value = "抽獎介面", notes = "抽獎介面，根據概率返回中獎商品")

    public CommonResult<Product> luckyDrawProduct(){

        CommonResult<Product> commonRes = productFeignService.luckyDrawProduct();

        String requestUrl = String.format("http://localhost:%s//consumer/luckyDraw", serverPort);

        commonRes.setUrl(requestUrl);

        return commonRes;

    }

}

2.3.抽獎介面實現

主要用到的抽獎商品類：

@Data

@AllArgsConstructor

@NoArgsConstructor

@ApiModel("使用者實體類")

public class Product

{

    @ApiModelProperty("主鍵id")

    private Integer id;   //主鍵id

    @ApiModelProperty("商品名稱")

    private String productName;  //商品名稱

    @ApiModelProperty("中獎率")

    private float winRate;  //中獎率 -- 請使用者輸入小數點後兩位

}

公共介面返回值封裝類：

@Data

@AllArgsConstructor

@NoArgsConstructor

public class CommonResult<T> {

    private Integer code;

    private T data;

    private String exception;

    private String msg;

    private boolean success;

    private String url;

}

返回結果列舉類：

@Getter

public enum ResultCodeEnum {

    /**

     * 返回結果列舉，每個列舉代表著一個狀態

     */

    SUCCESS(200, "操作成功！"),

    ERROR(400, "操作失敗！"),

    DATA_NOT_FOUND(401, "查詢失敗！"),

    PARAMS_NULL(402, "引數不能為空！"),

    PARAMS_ERROR(405, "引數不合法！"),

    NOT_LOGIN(403, "當前賬號未登入！");

    private Integer code;

    private String msg;

    ResultCodeEnum(Integer code, String msg) {

        this.code = code;

        this.msg = msg;

    }

}

主要的抽獎介面實現工具類：

public class LotteryUtil {

    /**

     * 抽獎設計介面：

     * 產生一個隨機數，0-5為一等獎商品，6-15為二等獎商品，16-40為三等獎商品，41-100為謝謝惠顧

     * 在比較的時候，比較隨機數（百分比）與獲取商品的概率（百分比）的絕對值，40%以下的才中獎

     * 之後計算隨機數與中獎概率的絕對值，選擇絕對值相差最小的那個為中獎商品

     * @param products

     * @return

     */

    public static Product luckyDraw(List<Product> products) {

        //1.產生一個隨機數

        int probabilityCount = 100;

        int randomNum = (int) (Math.random()* probabilityCount);

        //2.41-100表示不中獎

        if(randomNum > 40){

            return null;

        }

        Map<String, Product> map = new HashMap<>();

        List<Integer> list = new ArrayList<>();

        for (Product product : products) {

            int intValue = new BigDecimal(product.getWinRate() * 100).intValue();

            int absVal = Math.abs(randomNum - intValue);

            list.add(absVal);

        }

        Integer min = Collections.min(list);

        for (Product product : products) {

            int value = new BigDecimal(product.getWinRate() * 100).intValue();

            if(Math.abs(randomNum - value) == min){

                return product;

            }

        }

        return null;

    }

}