[Java知识库]Springcloud常用组件案例

? 今天倒腾一下Springcloud,整体感觉会Springboot,上手Springcloud也相对容易，下面简单梳理了Springcloud的几个组件；

整个项目结构

一、服务注册与发现

1.创建单节点注册中心

1.1 创建eureka-server模块并导入坐标

<dependencies>
     <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.8.7</version>
    </dependency> 
    
     <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        <version>3.0.3</version>
    </dependency>

</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

1.2 创建application.properties配置文件

spring.application.name=spring-cloud-eureka

eureka.instance.hostname=localhost
server.port=11111
# 不向注册中心注册自己
eureka.client.register-with-eureka=false
# 检测服务
eureka.client.fetch-registry=false
# 注册中心
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${server.port}/eureka/

1.3 创建启动类

@SpringBootApplication
@EnableEurekaServer //开启服务注册中心
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

1.4 创建eureka-client-userservice模块服并导入坐标

<dependencies>

    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.8.7</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <version>2.2.4.RELEASE</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        <version>3.0.3</version>
    </dependency>

</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR8</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>

1.5 创建配置文件

spring.application.name=user-service

eureka.instance.hostname=localhost
server.port=9999
service.port=11111

eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/

1.6 创建启动类

@SpringBootApplication
@EnableEurekaClient //开启服务注册
public class UserApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserApplication.class, args);
    }
}

1.7 创建测试接口

@RestController
public class UserController {
    @GetMapping("/getUser")
    public String getUser(){
        return "new User";
    }

}

1.8 测试

?2.创建高可用注册中心

拷贝一份eureka-server(也可直接修改配置文件)

?2.1 修改配置文件，使eureka-server、eureka-server2互为注册，配置如下：

spring.application.name=spring-cloud-eureka

eureka.instance.hostname=localhost
server.port=11111
service.port=22222
# 注册中心
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/

spring.application.name=spring-cloud-eureka

eureka.instance.hostname=localhost
server.port=22222
service.port=11111
# 注册中心
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/

2.2 同时修改user-serice模块的配置文件，如下所示：

spring.application.name=user-service

eureka.instance.hostname=localhost
server.port=9999
service.port=11111
service2.port=22222

eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

2.3 测试结果如下：

?

2.4?再起一个服务提供方user-service，改个端口即可

spring.application.name=user-service

eureka.instance.hostname=localhost
server.port=9998
service.port=11111
service2.port=22222

eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

二、ribbon?负载均衡

3.1 创建服务消费模块order-service,pom.xml配置如下：

<dependencies>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.8.7</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <version>2.2.4.RELEASE</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        <version>3.0.3</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-ribbon</artifactId>
        <version>1.3.1.RELEASE</version>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR8</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>

3.2 创建配置文件

spring.application.name=order-service

eureka.instance.hostname=localhost
server.port=9989
service.port=11111
service2.port=22222

eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

3.3 创建启动类，开启负载均衡

@EnableEurekaClient
@SpringBootApplication
public class OrderApplication {

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class,args);
    }
}

3.4 编写测试接口

@RestController
public class OrderController {

    @Autowired
    private RestTemplate restTemplate;
    @GetMapping("/user")
    public String getUser(){
        ResponseEntity<String> entity = restTemplate.getForEntity("http://user-service/getUser", String.class);
        return entity.getBody();
    }
}

3.5 测试

这里简单的使用要了轮询的方式

三、断路器?

这里断开一个user-service,再访问http://localhost:9989/user 会出现以下情形；

?

这里可引入断路器

1 pom.xml添加如下坐标

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-hystrix</artifactId>
    <version>1.3.1.RELEASE</version>
</dependency>

2.主启动类加如下注解

@EnableCircuitBreaker//开启断路器注解

这里也可用@SpringCloudApplication这一个注解代替三个注解，原因如下：

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootApplication
@EnableDiscoveryClient
@EnableCircuitBreaker
public @interface SpringCloudApplication {

}

3 对代码做简单改造处理

3.1 OrderController接口更改如下：

@RestController
public class OrderController {
    @Autowired
    private OrderService orderServiceImpl;
    @GetMapping("/user")
    public String getUser(){
        return orderServiceImpl.user();
    }
}

3.2 添加 OrderService 接口

public interface OrderService {
    public String user();
}

3.3 OrderService实现类更改如下

@Service
public class OrderServiceImpl implements OrderService {

    @Autowired
    private RestTemplate restTemplate;
    
    @HystrixCommand(fallbackMethod="getBackError")
    public String user() {
        ResponseEntity<String> entity = restTemplate.getForEntity("http://USER-SERVICE/getUser", String.class);
        return entity.getBody();
    }

    public String getBackError(){
        return "error";
    }
}

3.4 测试结果如下：

?

?四．Feign

1?Feign远程访问

1.1新建一个模块feign-order-service,pom.xml配置如下：

<dependencies>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.8.7</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.11.4</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <version>2.2.4.RELEASE</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        <version>2.2.9.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
        <version>2.2.9.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        <version>2.2.9.RELEASE</version>
    </dependency>

</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR8</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>

1.2 创建配置文件

spring.application.name=order-service2

eureka.instance.hostname=localhost
server.port=9979
service.port=11111
service2.port=22222

eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

1.3 创建启动类，并开启Feign功能

@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class,args);
    }
}

1.4 创建OrderController 接口

@RestController
public class OrderController {
    @Autowired
    private OrderService orderService;
    @GetMapping("/user")
    public String getUser(){
        return orderService.getUser();
    }
}

1.5 引入user-service服务

@FeignClient(value="user-service")
public interface OrderService {
    @GetMapping("getUser")
    public String getUser();
}

#全局关闭熔断功能
feign.hystrix.enabled=false 

2.服务降级

2.1?这里要配置feign.hystrix.enabled=true

spring.application.name=order-service2

eureka.instance.hostname=localhost
server.port=9979
service.port=11111
service2.port=22222
feign.hystrix.enabled=true
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

2.2 修改OrderService接口

@FeignClient(value="user-service",fallback = FallBack.class)
public interface OrderService {
    @GetMapping("getUser")
    public String getUser();
}

2.3?FallBack 类代码如下：

@Component
public class FallBack implements OrderService {
    public String getUser() {
        return "Error";
    }
}

五、Zuul 路由与过滤

1 路由功能

1.1 创建模块zuul-service,导入坐标

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
    <version>2.2.9.RELEASE</version>
</dependency>

1.2 开启zuul功能 @EnableZuulProxy

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

1.3 创建配置文件，如下所示：

spring.application.name=zuul-service

eureka.instance.hostname=localhost
server.port=9969
service.port=11111
service2.port=22222

zuul.routes.zuulname.path=/user/**
zuul.routes.zuulname.service-id=USER-SERVICE
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

注意：为了避免jar的不匹配问题，这里在<dependencyManagement>中引入了如下配置；

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.4.RELEASE</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>

1.4 测试结果如下：

?这里也可注释掉配置文件中的路由配置

spring.application.name=zuul-service

eureka.instance.hostname=localhost
server.port=9969
service.port=11111
service2.port=22222

#zuul.routes.zuulname.path=/user/**
#zuul.routes.zuulname.service-id=USER-SERVICE
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${service.port}/eureka/,http://${eureka.instance.hostname}:${service2.port}/eureka/

直接通过serverId访问，原因是zuul默认按serverId维护了一个映射；

?对于单独配置几个server的情况，可以使用zuul.ignored-services忽略掉所有，然后再单独配置；

2.过滤器

2.1 创建过滤器类

@Component
public class ZuulFilterImpl extends ZuulFilter {

    private Logger logger = LoggerFactory.getLogger(ZuulFilterImpl.class);

    /**
     * 过滤器类型
     * @return
     */
    @Override
    public String filterType() {
        return PRE_TYPE;
    }

    /**
     * 过滤器执行的顺序
     * @return
     */
    @Override
    public int filterOrder() {
        return 0;
    }

    /**
     * 过滤器是否需要执行
     * @return
     */
    @Override
    public boolean shouldFilter() {
        return true;
    }

    /**
     * 过滤器执行的具体逻辑
     * @return
     * @throws ZuulException
     */
    @Override
    public Object run() throws ZuulException {
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        logger.info("into run");

        return null;
    }
}

2.2 测试结果如下：

?六、配置中心

准备工作：

1 配置中心服务端

1.1 创建config-service模块，导入坐标

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-config-server</artifactId>
</dependency>

1.2 创建启动类，开启配置服务

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

1.3 配置文件如下：

spring.application.name=config-service
server.port=8888

spring.cloud.config.server.git.uri=
spring.cloud.config.label=master
spring.cloud.config.server.git.search-paths=main
spring.cloud.config.server.git.username=
spring.cloud.config.server.git.password=

1.4 测试

?2?配置客户端

2.1 创建配置客户端模块config-client,坐标如下：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>2.2.4.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR8</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.2.4.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>
<build>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

2.2 创建配置文件bootstrap.properties

#spring.config.name=application
spring.cloud.config.label=master
spring.cloud.config.profile=pro
spring.cloud.config.uri=http://localhost:8888/

2.3 创建application.properties配置文件

spring.application.name=config-client
server.port=55555

2.4.创建测试接口

@RefreshScope
@RestController
public class ClientController {

    @Autowired
    private Environment environment;
    @Value("${server-port}")
    private String port;

    @GetMapping("/port")
    public String getProperties(){
        String property = environment.getProperty("server-port");
        return property;
    }
}

2.5 创建启动类

public class ClientApplication {
    public static void main(String[] args) {
        SpringApplication.run(ClientApplication.class,args);
    }
}

2.6 测试结果如下：