* 创建一个 Maven 项目 microservice-provider-user ~~~bash mvn archetype:generate -DgroupId=com.shiyanlou -DartifactId=microservice-provider-user -DarchetypeArtifactId=maven-archetype-quickstart ~~~ 依赖如下： ~~~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>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.7.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.shiyanlou</groupId> <artifactId>microservice-provider-user</artifactId> <version>0.0.1-SNAPSHOT</version> <name>microservice-provider-user</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- 引入H2数据库，一种内嵌的数据库，语法类似MySQL --> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </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> </dependencies> <!-- 引入spring cloud的依赖，不能少，主要用来管理Spring Cloud生态各组件的版本 --> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>Finchley.SR2</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <!-- 添加spring-boot的maven插件，不能少，打jar包时得用 --> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> ~~~ * 在`com.shiyanlou`下创建实体类`User.java`： ~~~java package com.shiyanlou; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import javax.persistence.*; import java.math.BigDecimal; @Entity @Data @NoArgsConstructor @AllArgsConstructor public class User { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @Column private String username; @Column private String name; @Column private Integer age; @Column private BigDecimal balance; } ~~~ 其中使用到了[Lombok](https://projectlombok.org/)插件，不过你可以暂时不用管这个是什么。 * 创建 DAO，在`com.shiyanlou`下创建`UserRepository.java`: ~~~java package com.shiyanlou; import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.stereotype.Repository; @Repository public interface UserRepository extends JpaRepository<User,Long> { } ~~~ * 在`com.shiyanlou`下创建`UserController.java`，提供 RESTful 接口： ~~~java package com.shiyanlou; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import java.util.Optional; @RequestMapping("/users") @RestController public class UserController { @Autowired UserRepository userRepository; @GetMapping("/{id}") public Optional<User> findById(@PathVariable Long id){ return this.userRepository.findById(id); } } ~~~ 上面代码通过`@GetMapping`注解提供了一个`GET`请求方式的`/users/{id}`。 * 编写启动类`App.java`，该类是程序的启动入口： ~~~java package com.shiyanlou; import org.springframework.boot.ApplicationRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.Bean; import java.math.BigDecimal; import java.util.stream.Stream; @SpringBootApplication public class App { public static void main(String[] args) { SpringApplication.run(App.class, args); } @Bean ApplicationRunner init(UserRepository repository){ return args -> { User user1 = new User(1L, "account1", "张三", 20, new BigDecimal(100.00)); User user2 = new User(2L, "account2", "李四", 28, new BigDecimal(180.00)); User user3 = new User(3L, "account3", "王五", 32, new BigDecimal(280.00)); Stream.of(user1, user2, user3) .forEach(repository::save); }; } } ~~~ * 编写配置文件`src/main/resources/application.yml`： ~~~yaml server: # 指定Tomcat端口 port: 8000 spring: application: # 给这个服务取名叫做：microservice-provider-user name: microservice-provider-user jpa: # 让hibernate打印执行的SQL show-sql: true logging: level: root: INFO # 配置日志级别，让hibernate打印出执行的SQL参数 org.hibernate: INFO org.hibernate.type.descriptor.sql.BasicBinder: TRACE org.hibernate.type.descriptor.sql.BasicExtractor: TRACE ~~~ * 最终目录结构如下图：  * 通过 maven 构建并运行该程序： ~~~bash mvn spring-boot:run ~~~ 当窗口出现如下信息的时候，你可以请求该应用看看： ~~~ 2019-03-12 23:06:45.812 INFO 17362 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8000 (http) 2019-03-12 23:06:45.870 INFO 17362 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2019-03-12 23:06:45.871 INFO 17362 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.35 2019-03-12 23:06:45.919 INFO 17362 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [/Users/tanjian/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:.] 2019-03-12 23:06:46.013 INFO 17362 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2019-03-12 23:06:46.013 INFO 17362 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1893 ms 2019-03-12 23:06:46.082 INFO 17362 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/] 2019-03-12 23:06:46.086 INFO 17362 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2019-03-12 23:06:46.087 INFO 17362 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2019-03-12 23:06:46.088 INFO 17362 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2019-03-12 23:06:46.089 INFO 17362 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2019-03-12 23:06:46.268 INFO 17362 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting... 2019-03-12 23:06:46.449 INFO 17362 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed. 2019-03-12 23:06:46.516 INFO 17362 --- [ main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default' 2019-03-12 23:06:46.560 INFO 17362 --- [ main] o.hibernate.jpa.internal.util.LogHelper : HHH000204: Processing PersistenceUnitInfo [ name: default ...] 2019-03-12 23:06:46.882 INFO 17362 --- [ main] org.hibernate.Version : HHH000412: Hibernate Core {5.2.17.Final} 2019-03-12 23:06:46.884 INFO 17362 --- [ main] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found 2019-03-12 23:06:46.953 INFO 17362 --- [ main] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {5.0.1.Final} 2019-03-12 23:06:47.109 INFO 17362 --- [ main] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.H2Dialect Hibernate: drop table user if exists Hibernate: drop sequence if exists hibernate_sequence Hibernate: create sequence hibernate_sequence start with 1 increment by 1 Hibernate: create table user (id bigint not null, age integer, balance decimal(19,2), name varchar(255), username varchar(255), primary key (id)) 2019-03-12 23:06:47.810 INFO 17362 --- [ main] o.h.t.schema.internal.SchemaCreatorImpl : HHH000476: Executing import script 'org.hibernate.tool.schema.internal.exec.ScriptSourceInputNonExistentImpl@24629999' 2019-03-12 23:06:47.815 INFO 17362 --- [ main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default' 2019-03-12 23:06:48.171 INFO 17362 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-03-12 23:06:48.387 INFO 17362 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@2e96c6f6: startup date [Tue Mar 12 23:06:44 CST 2019]; root of context hierarchy 2019-03-12 23:06:48.438 WARN 17362 --- [ main] aWebConfiguration$JpaWebMvcConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning 2019-03-12 23:06:48.487 INFO 17362 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/users/{id}],methods=[GET]}" onto public java.util.Optional<com.shiyanlou.labs.spring.cloud.microserviceprovideruser.User> com.shiyanlou.labs.spring.cloud.microserviceprovideruser.UserController.findById(java.lang.Long) 2019-03-12 23:06:48.493 INFO 17362 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest) ~~~ 你可以新打开一个终端，然后输入如下命令来模拟请求： ~~~bash curl http://localhost:8000/users/1 ~~~ 不出所料，会出现如下响应，代表着用户微服务就编写好了： ~~~json { "id": 1, "username": "account1", "name": "张三", "age": 20, "balance": 100.0 } ~~~  接下来，让我们开始编写服务消费者【电影微服务】。