上一章讲了Ribbon的负载均衡，并且使用RestTemplate进行了调用，本章讲解另外一种负载均衡的调用
即，Feign的声明式调用
和上一章一样，我们将启动1个eureka-server 用于服务的注册，2个eureka-client 模拟2个客户端 1个 eureka-feign-client 用于对客户端的声明式调用
1. 创建一个maven项目
在pom中设置
<packaging>pom</packaging>
2. 新建eureka-server，端口为7001
主要配置如下
2.1 pom文件
<?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>2.2.5.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.devin</groupId> <artifactId>eureka-server</artifactId> <version>0.0.1-SNAPSHOT</version> <name>eureka-server</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <spring-cloud.version>Hoxton.SR3</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-sleuth</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> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>${spring-cloud.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
2.2. 启动类
package com.devin.eurekaserver;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
2.3 权限配置类
package com.devin.eurekaserver.config;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
//关闭csrf
super.configure(http);
//开启认证
http.csrf().disable();
}
}
2.4 application.yml 配置
eureka-server 的启动端口为 7001
server:
port: 7001 #启动端口
spring:
#应用名称
application:
name: eureka-server
#安全配置
security:
basic:
enabled: true
user:
name: dev
password: 123456
#eureka配置
eureka:
server:
#设置扫描失效服务的间隔时间
eviction-interval-timer-in-ms: 20000
enable-self-preservation: true
instance:
hostname: localhost
leaseRenewalIntervalInSeconds: 10
health-check-url-path: /actuator/health
client:
register-with-eureka: false #false:不作为一个客户端注册到注册中心
fetch-registry: false #为true时，可以启动，但报异常：Cannot execute request on any known server
service-url:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
# health endpoint是否必须显示全部细节。默认情况下, /actuator/health 是公开的，并且不显示细节。
# 设置actuator开关
management:
security:
enabled: false
endpoints:
web:
exposure:
include: "*"
endpoint:
health:
show-details: ALWAYS
3. eureka-client 配置
3.1 pom.xml配置
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <version>2.1.8.RELEASE</version> </dependency>
3.2 启动类
package com.devin.eurekaclient;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@EnableEurekaClient
@SpringBootApplication
public class EurekaClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
}
3.3 新建Controller
在controller中定义了一个get和一个post请求的方法
package com.devin.eurekaclient.controller;
import com.devin.eurekaclient.vo.User;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;
/**
* @author Devin Zhang
* @className HelloController
* @description TODO
* @date 2020/3/28 10:45
*/
@RestController
public class HelloController {
@Value("${server.port}")
private Integer port;
@GetMapping("/sayHello")
public String sayHello(String name) {
return "Hello ," + name + " ,this response is from eureka client port:" + port;
}
@PostMapping("/login")
public String login(@RequestBody User user) {
if (user.getUserName().equals("devin") && user.getUserPass().equals("123456")) {
return "success from " + port;
}
return "fail from " + port;
}
}
对应的model
package com.devin.eurekaclient.vo;
/**
* @author Devin Zhang
* @className User
* @description TODO
* @date 2020/3/30 13:33
*/
public class User {
private String userName;
private String userPass;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPass() {
return userPass;
}
public void setUserPass(String userPass) {
this.userPass = userPass;
}
}
3.4 application.yml 配置文件
后续eureka-client将启动2个端口 7002 和 7003 ，这两个实例将分别在eueka-server 7001 注册
eureka:
auth:
user: dev
password: 123456
client:
serviceUrl:
defaultZone: http://${eureka.auth.user}:${eureka.auth.password}@localhost:7001/eureka/
instance:
#使用IP进行注册
prefer-ip-address: true
#配置实例的注册ID
instance-id: ${spring.cloud.client.ip-address}:${server.port}
#心跳时间，即服务续约间隔时间（缺省为30s）
lease-renewal-interval-in-seconds: 5
#发呆时间，即服务续约到期时间（缺省为90s）
lease-expiration-duration-in-seconds: 10
health-check-url-path: /actuator/health
server:
port: 7002
spring:
application:
name: eureka-client
4. eureka-feign-client
通过feign去调用eureka-client，feign将自动实现客户端服务调用的负载均衡
4.1 pom.xml
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> <version>2.1.1.RELEASE</version> </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-web</artifactId> <version>2.1.8.RELEASE</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.3</version> </dependency> <dependency> <groupId>io.github.openfeign</groupId> <artifactId>feign-httpclient</artifactId> <version>10.1.0</version> </dependency>
ps: 后面两个包是为了解决feign的get请求时会报如下错误，同时需要在配置文件中添加 feign.httpclient.enabled=true
{"timestamp":"2020-03-30T02:03:50.634+0000","status":405,"error":"Method Not Allowed","message":"Request method 'POST' not supported",
4.2 启动类
该项目也作为一个client在服务端7001 注册
package com.devin.eurekafeignclient;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class EurekaFeignClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaFeignClientApplication.class, args);
}
}
4.3 Feign的配置类
package com.devin.eurekafeignclient.config;
import feign.Retryer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import static java.util.concurrent.TimeUnit.SECONDS;
/**
* @author Devin Zhang
* @className FeignConfig
* @description TODO
* @date 2020/3/28 16:50
*/
@Configuration
public class FeignConfig {
@Bean
public Retryer feignRetryer() {
return new Retryer.Default(100, SECONDS.toSeconds(1), 5);
}
}
4.4 Feign去声明式调用eureka-clent的接口服务
feign将去调用我们再eureka-client中定义的get和post对应的接口
package com.devin.eurekafeignclient.service;
import com.devin.eurekafeignclient.config.FeignConfig;
import com.devin.eurekafeignclient.vo.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestParam;
/**
* @author Devin Zhang
* @className FeignHelloService
* @description TODO
* @date 2020/3/28 16:49
*/
@FeignClient(value = "eureka-client", configuration = FeignConfig.class)
public interface FeignHelloService {
@GetMapping(value = "/sayHello")
String sayHello(@RequestParam String name);
@PostMapping(value = "/login", consumes = "application/json")
String login(@RequestBody User user);
}
package com.devin.eurekafeignclient.vo;
/**
* @author Devin Zhang
* @className User
* @description TODO
* @date 2020/3/30 13:39
*/
public class User {
private String userName;
private String userPass;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPass() {
return userPass;
}
public void setUserPass(String userPass) {
this.userPass = userPass;
}
}
4.5 controller测试类
package com.devin.eurekafeignclient.controller;
import com.devin.eurekafeignclient.service.FeignHelloService;
import com.devin.eurekafeignclient.vo.User;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
/**
* @author Devin Zhang
* @className FeignHelloController
* @description TODO
* @date 2020/3/28 17:01
*/
@RestController
public class FeignHelloController {
@Resource
private FeignHelloService feignHelloService;
@GetMapping(value = "/sayHelloFromFeign")
public String sayHelloFromFeign(String name) {
return feignHelloService.sayHello(name);
}
@PostMapping(value = "/loginFromFeign")
public String sayHelloFromFeign(User user) {
return feignHelloService.login(user);
}
}
4.6 eureka-feign-client application.yml 配置
feigin client 7004 将在eureka-server 7001注册
eureka:
auth:
user: dev
password: 123456
client:
serviceUrl:
defaultZone: http://${eureka.auth.user}:${eureka.auth.password}@localhost:7001/eureka/
instance:
#使用IP进行注册
prefer-ip-address: true
#配置实例的注册ID
instance-id: ${spring.cloud.client.ip-address}:${server.port}
#心跳时间，即服务续约间隔时间（缺省为30s）
lease-renewal-interval-in-seconds: 5
#发呆时间，即服务续约到期时间（缺省为90s）
lease-expiration-duration-in-seconds: 10
health-check-url-path: /actuator/health
server:
port: 7004
spring:
application:
name: eureka-feign-client
feign:
httpclient:
enabled: true
5. 测试
启动 eureka-server 7001
启动eureka-client 7002,7003
java -jar eureka-client-0.0.1-SNAPSHOT.jar --server.port=7002
java -jar eureka-client-0.0.1-SNAPSHOT.jar --server.port=7003
启动 eureka-feign-client 7004
服务的注册情况如下：
验证
访问get请求 http://localhost:7004/sayHelloFromFeign?name=devin 可以看到调用的eureka-clent在7002和7003之间进行切换
Post请求，使用 SoupUI发送post请求，可以看到后端收到参数，自动封装为一个model，返回结果，并且在7002,7003之间负载均衡
至此，feign的声明式调用完成。