声明式服务调用SpringCloud Feign

约定不等于承诺〃 2022-05-08 01:12 277阅读 0赞

# 声明式服务调用SpringCloud Feign #

### 文章目录 ###

*  声明式服务调用SpringCloud Feign
 *   *   *  快速入门
         *  参数绑定
         *  继承特性
         *  Ribbon 配置
         *   *  全局配置
             *  指定服务配置
             *  重试机制
         *  Hystrix 配置
         *   *  全局配置
             *  禁用 Hystrix
             *  指定命令配置
             *  服务降级配置
         *  其他配置
         *   *  请求压缩
         *  日志配置

### 快速入门 ###

创建项目 feign-consumer 9010

pom 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.zk.springcloud.feign</groupId>
        <artifactId>springcloud-feign</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>springcloud-feign</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.5.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
            <spring-cloud.version>Finchley.SR1</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.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>
    
    </project>

创建应用启动类，并通过 @EnableFeignClients 注解开启 Spring Cloud Feign 的支持功能

@SpringBootApplication @EnableFeignClients @EnableDiscoveryClient public class SpringcloudFeignApplication { public static void main(String[] args) { SpringApplication.run(SpringcloudFeignApplication.class, args); } }

定义 HelloService 接口，通过 @FeignClient 注解指定服务名来绑定服务，然后再使用 SpringMVC 的注解来绑定具体该服务提供的 REST 接口

这里服务名不区分大小写，所以使用 SERIVCE-USER 和 service-user 都是可以的

@FeignClient("SERIVCE-USER") @Service public interface HelloService { @RequestMapping("/hello") String hello(); }

方法调用

@RestController public class ConsumerController { @Autowired HelloService helloService; @GetMapping(value = "/feign-consumer") public String helloConsumer(){ return helloService.hello(); } }

配置文件

spring.application.name=feign-consumer
    server.port=9010
    
    eureka.client.service-url.defaultZone=http://localhost:9001/eureka/,http://localhost:9004/eureka/

测试验证，如之前验证 Ribbon 客户端负载均衡一样，先启动注册中心以及两个 SERVICE-USER ，然后启动 FEIGN-CONSUMER ，多次调用 [http://localhost:9010/feign-consumer][http_localhost_9010_feign-consumer] ， 结果与之前 Ribbon 实现时一样的效果 Hello World 9006 和 Hello World 9003 切换显示。依然是利用 Ribbon 维护对 SERVICE-USER 的服务列表信息，并且通过轮询实现了客户端负载均衡。

### 参数绑定 ###

feign-consumer 9010 , HelloService 添加方法

@GetMapping(value = "/hello1")
        String hello(@RequestParam("name") String name);
    
        @GetMapping(value = "/hello2")
        User hello(@RequestHeader("name") String name,@RequestHeader("password") String password);
    
        @PostMapping(value = "/hello3")
        String hello(@RequestBody User user);

User 对象如下, 这里必须要有 User 的默认构造函数，不然 Spring Cloud Feign 根据 JSON 字符串转换 User 对象会抛出异常

public class User { String name; String password; public User() { } public User(String name, String password) { this.name = name; this.password = password; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @Override public String toString() { return "User{" + "name='" + name + '\'' + ", password='" + password + '\'' + '}'; } }

对 UserService 9003 项目改造

@FeignClient("SERIVCE-USER") @Service public interface HelloService { @RequestMapping("/hello") String hello(); @GetMapping(value = "/hello1") String hello(@RequestParam("name") String name); @GetMapping(value = "/hello2") User hello(@RequestHeader("name") String name,@RequestHeader("password") String password); @PostMapping(value = "/hello3") String hello(@RequestBody User user); }

在 feign-consumer 9010 项目添加调用

@GetMapping(value = "/feign-consumer2") public String helloConsumer2(){ StringBuilder sb = new StringBuilder(); sb.append(helloService.hello()).append("\n"); sb.append(helloService.hello("DIDI")).append("\n"); sb.append(helloService.hello("DIDI","123456")).append("\n"); sb.append(helloService.hello(new User("DIDI","admin"))).append("\n"); return sb.toString(); }

访问 [http://localhost:9010/feign-consumer2][http_localhost_9010_feign-consumer2] 可获取 Hello World 9003 Hello DIDI User\{name=‘DIDI’, password=‘123456’\} Hello DIDI, admin

### 继承特性 ###

创建名为 user-service-api 的 maven 项目

pom 依赖

复制上节中的 User 对象到 user-service-api 工程

创建 HelloService 接口

package com.zk.springcloud; import org.springframework.web.bind.annotation.*; @RequestMapping("/refactor") public interface HelloService { @GetMapping(value = "/hello4") String hello(@RequestParam("name") String name); @GetMapping(value = "/hello5") User hello(@RequestHeader("name") String name,@RequestHeader("password") String password); @PostMapping(value = "/hello6") String hello(@RequestBody User user); }

对 user-service 和 feign-consumer 重构

对 user-service 重构

添加 user-serivce-api的依赖

<dependency>
                <groupId>com.zk.springcloud</groupId>
                <artifactId>springcloud-user-service-api</artifactId>
                <version>0.0.1-SNAPSHOT</version>
            </dependency>

创建 RefactorHelloController 类继承 user-service-api 中定义的 HelloService 接口

package com.zk.springcloud.service; import com.zk.springcloud.HelloService; import com.zk.springcloud.User; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestHeader; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; @RestController public class RefactorHelloController implements HelloService { @Override public String hello(@RequestParam("name") String name) { return "Hello " + name; } @Override public User hello(@RequestHeader("name") String name,@RequestHeader("password") String password) { return new User(name,password); } @Override public String hello(@RequestBody User user) { return "Hello " + user.getName() + ", " + user.getPassword(); } }

对 feign-consumer 重构

创建 RefactorHelloService 接口

import org.springframework.stereotype.Service; @FeignClient(value = "SERIVCE-USER") @Service public interface RefactorHelloService extends HelloService { }

添加调用

@GetMapping(value = "/feign-consumer3") public String helloConsumer3(){ StringBuilder sb = new StringBuilder(); sb.append(refactorHelloService.hello("MIMI")).append("\n"); sb.append(refactorHelloService.hello("MIMI","123456")).append("\n"); sb.append(refactorHelloService.hello(new com.zk.springcloud.User("MIMI","123456"))).append("\n"); return sb.toString(); }

访问 [http://localhost:9010/feign-consumer3][http_localhost_9010_feign-consumer3] 获得如下结果

Hello MIMI User{name='MIMI', password='123456'} Hello MIMI, 123456

### Ribbon 配置 ###

#### 全局配置 ####

ribbon.ConnectTimeout=500
    ribbon.ReadTimeout=5000

#### 指定服务配置 ####

serivce-user.ribbon.ConnectTimeout=500
    serivce-user.ribbon.ReadTimeout=2000
    serivce-user.ribbon.okToRetryOnAllOperations=true
    serivce-user.ribbon.MaxAutoRetriesNextServer=2
    serivce-user.ribbon.MaxAutoRetries=1

#### 重试机制 ####

feign-consumer 添加上述指定服务配置

user-service 修改如下超时

@GetMapping(value = "/hello") public String hello() throws InterruptedException { int sleepTime = new Random().nextInt(3000); log.info("sleepTime: " + sleepTime); Thread.sleep(sleepTime); return "Hello World 9003"; }

访问 [http://localhost:9010/feign-consumer][http_localhost_9010_feign-consumer]

在 user-service 可以看到重试日志

### Hystrix 配置 ###

#### 全局配置 ####

hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=5000
    #关闭 Hystrix 功能
    #feign.hystrix.enabled=false
    #关闭熔断功能
    #hystrix.command.default.execution.timeout.enabled=false

#### 禁用 Hystrix ####

全局关闭 Hystrix

#关闭 Hystrix 功能
    feign.hystrix.enabled=false

针对某个客户端关闭 Hystrix ，通过使用 @Scope(“prototype”) 注解为指定的客户端配置 Feign.Builder 实例

构建一个关闭 Hystrix 的配置类

@Configuration public class DisableHystrixConfiguration { @Bean @Scope("prototype") public Feign.Builder feignBuilder(){ return Feign.builder(); } }

在 HelloService 的 @FeignClient 注解中，通过 configuration 参数引入上面实例的配置

@FeignClient(value = "SERIVCE-USER",configuration = DisableHystrixConfiguration.class) @Service public interface HelloService { ··· }

#### 指定命令配置 ####

针对尝试机制中对 /hello 接口的熔断时间的配置可通过如下配置

hystrix.command.hello.execution.isolation.thread.timeoutInMilliseconds=5000

#### 服务降级配置 ####

对 feign-consumer 工程进行改造

package com.zk.springcloud.feign; import org.springframework.stereotype.Component; import org.springframework.web.bind.annotation.RequestHeader; import org.springframework.web.bind.annotation.RequestParam; @Component public class HelloServiceFallBack implements HelloService { @Override public String hello() { return "error"; } @Override public String hello(@RequestParam("name") String name) { return "error"; } @Override public User hello(@RequestHeader("name") String name,@RequestHeader("password") String password) { return new User("未知","0"); } @Override public String hello(User user) { return "error"; } }

在服务绑定接口 HelloService 中，通过 @FeignClient 注解的 fallback 属性来指定对应的服务降级实现类

@FeignClient(value = "SERIVCE-USER",fallback = HelloServiceFallBack.class) @Service public interface HelloService { @RequestMapping("/hello") String hello(); @GetMapping(value = "/hello1") String hello(@RequestParam("name") String name); @GetMapping(value = "/hello2") User hello(@RequestHeader("name") String name,@RequestHeader("password") String password); @PostMapping(value = "/hello3") String hello(@RequestBody User user); }

配置文件开启 feign.hystrix

feign.hystrix.enabled=true

将类 DisableHystrixConfiguration 注释

将 user-service 服务关闭，访问 [http://localhost:9010/feign-consumer2][http_localhost_9010_feign-consumer2] 获得如下结果：

error error User{name='未知', password='0'} error

### 其他配置 ###

#### 请求压缩 ####

feign.compression.request.enabled=true
    feign.compression.response.enabled=true
    #设置压缩的大小下限，超过的才进行压缩,以下配置为默认值
    feign.compression.request.mime-types=text/xml,application/xml,application/json
    feign.compression.request.min-request-size=2048

### 日志配置 ###

logging.level.com.zk.springcloud.feign.HelloService=DEBUG

feign-consumer 启动类配置

@SpringBootApplication @EnableFeignClients @EnableDiscoveryClient public class SpringcloudFeignApplication { @Bean Logger.Level feignLoggerLevel(){ return Logger.Level.FULL; } public static void main(String[] args) { SpringApplication.run(SpringcloudFeignApplication.class, args); } }

也可以通过实现配置类，然后在具体的Feign 客户端来指定配置类以实现是否要调整不同的日志界别

@Configuration public class FullLogConfiguration { @Bean Logger.Level feignLoggerLevel(){ return Logger.Level.FULL; } }

调用 [http://localhost:9010/feign-consumer][http_localhost_9010_feign-consumer]

请求详细日志

2018-10-08 14:49:34.051 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] ---> GET http://SERIVCE-USER/hello HTTP/1.1
    2018-10-08 14:49:34.051 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] ---> END HTTP (0-byte body)
    2018-10-08 14:49:34.872 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] <--- HTTP/1.1 200 (821ms)
    2018-10-08 14:49:34.872 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] content-length: 16
    2018-10-08 14:49:34.873 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] content-type: text/plain;charset=UTF-8
    2018-10-08 14:49:34.873 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] date: Mon, 08 Oct 2018 06:49:34 GMT
    2018-10-08 14:49:34.873 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] 
    2018-10-08 14:49:34.873 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] Hello World 9003
    2018-10-08 14:49:34.873 DEBUG 21632 --- [-SERIVCE-USER-5] com.zk.springcloud.feign.HelloService    : [HelloService#hello] <--- END HTTP (16-byte body)

[http_localhost_9010_feign-consumer]: http://localhost:9010/feign-consumer
[http_localhost_9010_feign-consumer2]: http://localhost:9010/feign-consumer2
[http_localhost_9010_feign-consumer3]: http://localhost:9010/feign-consumer3