Spring Cloud开发实践 - 02 - Eureka服务和接口定义
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服务注册 EurekaServer
Eureka服务模块只有三个文件, 分别是pom.xml, application.yml 和 EurekaServerApplication.java, 内容如下
pom.xml
spring-boot-maven-plugin: 使用 goal=repackage 可以打包出一个包含所有依赖的fat jar
maven-deploy-plugin: skip=true 表示当执行deploy时, 这个模块不会被提交到maven的repository
<?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> <parent> <groupId>com.rockbb</groupId> <artifactId>scot</artifactId> <version>1.0-SNAPSHOT</version> <relativePath>../scot/pom.xml</relativePath> </parent> <artifactId>scot-eureka</artifactId> <packaging>jar</packaging> <name>Scot: Eureka Server</name> <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-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <finalName>scot-eureka</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-resources-plugin</artifactId> </plugin> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <executions> <execution> <goals> <goal>repackage</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-deploy-plugin</artifactId> <configuration> <skip>true</skip> </configuration> </plugin> </plugins> </build> </project>
application.yml
将自己配置为 Eureka Server
server: port: ${PORT:8761} eureka: instance: hostname: localhost client: registerWithEureka: false fetchRegistry: false server: enableSelfPreservation: true renewalPercentThreshold: 0.1
EurekaServerApplication.java
@EnableEurekaServer @SpringBootApplication public class EurekaserverApplication { public static void main(String[] args) { SpringApplication.run(EurekaserverApplication.class, args); } }
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接口定义 Commons API
scot-commons-api模块定义了服务的接口Service和参数类型DTO. 因为Spring Cloud的特殊性, 这里的Service定义使用了@FeignClient和@RequestMapping注解, 这样在被下游调用时, 可以通过 @EnableFeignClients(basePackages = {"com.rockbb.scot.commons.api"}) 很方便地将服务引入.
本模块只有三个文件, pom.xml, UserDTO.java, UserDTOService.java
pom.xml
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>com.rockbb</groupId> <artifactId>scot</artifactId> <version>1.0-SNAPSHOT</version> <relativePath>../scot/pom.xml</relativePath> </parent> <artifactId>scot-commons-api</artifactId> <packaging>jar</packaging> <name>Scot: Commons API</name> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency> <dependency> <groupId>com.rockbb</groupId> <artifactId>scot-commons-lib</artifactId> <version>${project.version}</version> </dependency> </dependencies> </project>
UserDTO.java
注意如果要添加带参数的 constructor, 一定要把无参的constructor也加上, 否则下游无法将对象反序列化.
public class UserDTO implements Serializable { private String id; private String name; public UserDTO initialize(String id, String name) { this.id = id; this.name = name; return this; } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
UserDTOService.java
- @FeignClient 的value, 来自于 scot-commons-impl 模块的 spring.application.name, 多个DTOService可以使用相同的value.
- @RequestParam 一定要添加 value = "xx" , 否则在调用中即使你指定了method=GET, feign依然会使用POST进行调用, 导致错误
- @RequestMapping 可以像Controller一样同时定义于class和method
@FeignClient(value = "scot-commons") @RequestMapping(value = "/user") public interface UserDTOService { @RequestMapping(value = "/diagnos", method = RequestMethod.GET) String diagnos(@RequestParam(value = "name") String name); @RequestMapping(value = "/get", method = RequestMethod.GET) UserDTO get(@RequestParam(value = "id") String id); @RequestMapping(value = "/list", method = RequestMethod.GET) List<UserDTO> list(); @RequestMapping(value = "/count", method = RequestMethod.GET) long count(); }
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