服務提供者和服務消費者,名詞非常的高大上,但是其實很簡單,我們看什么是服務提供者,什么是服務消費者,服務的被調用方是服務的提供者,服務的調用方是消費者,以我們之前的電影系統為例,一個用戶發起了購票的請求,發現滿足要求了,去查當前用戶的信息,然后在這種場景下,電影微服務就是一個服務消費者,用戶微服務就是一個服務提供者,用戶微服務提供的一個接口被他消費了,是這個意思

編寫一個服務提供者,然后再編寫一個簡單的消費者,還是以電影銷售系統為例,我們來模擬這種情況,發起一個遠程的調用,首先我們寫一個服務提供者,我們先寫服務提供者,microservice-simple-provider-user,國內阿里云的鏡像,這樣下載會比較快,他的parent是spring-boot-starter-parent,首先我們寫一些建表語句,drop table user; create table user(id bigint generated by default as identity,username varchar(40),name varchar(20),age int(3),balance decimal(10,2), primary key(id) );balance是余額插入一些數據insert into user(id,username, name, age, balance) values(1,'user1', '張三', 20, 100.00); insert into user(id,username, name, age, balance) values(2,'user2', '李四', 20, 100.00); insert into user(id,username, name, age, balance) values(3,'user3', '王五', 20, 100.00); insert into user(id,username, name, age, balance) values(4,'user4', '馬六', 20, 100.00);@GetMapping它是一個組合注解,它是在Spring4.3以后支持的,同樣還有PostMapping,PutMapping,DeleteMapping,GetMapping他其實相當于RequestMapping,RequestMethod的Get的混合注解,/*** Annotation for mapping HTTP {@code GET} requests onto specific handler* methods.** <p>Specifically, {@code @GetMapping} is a <em>composed annotation</em> that* acts as a shortcut for {@code @RequestMapping(method = RequestMethod.GET)}.*** @author Sam Brannen* @since 4.3* @see PostMapping* @see PutMapping* @see DeleteMapping* @see PatchMapping* @see RequestMapping*/ @Target(ElementType.METHOD) @Retention(RetentionPolicy.RUNTIME) @Documented @RequestMapping(method = RequestMethod.GET) public @interface GetMapping {@RestController其實也是一個混合注解,相當于加了ResonseBody和Controller,/*** A convenience annotation that is itself annotated with* {@link Controller @Controller} and {@link ResponseBody @ResponseBody}.* <p>* Types that carry this annotation are treated as controllers where* {@link RequestMapping @RequestMapping} methods assume* {@link ResponseBody @ResponseBody} semantics by default.** <p><b>NOTE:</b> {@code @RestController} is processed if an appropriate* {@code HandlerMapping}-{@code HandlerAdapter} pair is configured such as the* {@code RequestMappingHandlerMapping}-{@code RequestMappingHandlerAdapter}* pair which are the default in the MVC Java config and the MVC namespace.* In particular {@code @RestController} is not supported with the* {@code DefaultAnnotationHandlerMapping}-{@code AnnotationMethodHandlerAdapter}* pair both of which are also deprecated.** @author Rossen Stoyanchev* @author Sam Brannen* @since 4.0*/ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Controller @ResponseBody public @interface RestController { <?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.learn</groupId><artifactId>microservice-simple-provider-user</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.12.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><thymeleaf.version>3.0.9.RELEASE</thymeleaf.version><thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version></properties><dependencies><dependency><!-- 引入web模塊 --><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!-- Spring Boot進行單元測試的模塊 --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jdbc</artifactId></dependency> <dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><!-- 引入druid數據源 --><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.1.8</version></dependency><dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.2</version> </dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency></dependencies><!-- 這個插件,可以將應用打包成一個可執行的jar包 --><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project> package com.learn.cloud.controller;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.RestController;import com.learn.cloud.entity.User; import com.learn.cloud.mapper.UserMapper;@RestController public class UserController {@Autowiredprivate UserMapper userMapper;@GetMapping("/simple/{id}")public User findById(@PathVariable Long id) {return this.userMapper.getUserById(id);}} package com.learn.cloud.mapper;import org.apache.ibatis.annotations.Mapper;import com.learn.cloud.entity.User;//@Mapper或者@MapperScan將接口掃描裝配到容器中 @Mapper public interface UserMapper {public User getUserById(Long id); } <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.learn.cloud.mapper.UserMapper"><select id="getUserById" resultType="com.learn.cloud.entity.User">select * from user where id = #{id}</select></mapper> package com.learn.cloud.entity;import java.math.BigDecimal;public class User {private Long id;private String username;private String name;private Short age;private BigDecimal balance;public Long getId() {return this.id;}public void setId(Long id) {this.id = id;}public String getUsername() {return this.username;}public void setUsername(String username) {this.username = username;}public String getName() {return this.name;}public void setName(String name) {this.name = name;}public Short getAge() {return this.age;}public void setAge(Short age) {this.age = age;}public BigDecimal getBalance() {return this.balance;}public void setBalance(BigDecimal balance) {this.balance = balance;} } package com.learn.cloud;import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;@MapperScan(value="com.learn.cloud.mapper") @SpringBootApplication public class MicroserviceSimpleProviderUserApplication {public static void main(String[] args) {SpringApplication.run(MicroserviceSimpleProviderUserApplication.class, args);} } #debug=true server.port=7900#server.context-path=/boot02spring.http.encoding.charset=UTF-8 spring.http.encoding.enabled=true spring.http.encoding.force=truelogging.level.com.learn=trace #logging.file=D:/springboot.log logging.file=springboot.log #logging.path=/spring/log logging.pattern.console=%d{yyyy-MM-dd} [%thread] %-5level %logger{50} - %msg%n logging.pattern.file=%d{yyyy-MM-dd} ==== [%thread] %-5level ==== %logger{50} ==== %msg%n #spring.resources.static-locations=classpath:/hello,classpath:/learnspring.datasource.username=root spring.datasource.password=123456 spring.datasource.url=jdbc:mysql://59.110.158.145:3306/SpringCloud?useSSL=false&useUnicode=true&characterEncoding=UTF-8 spring.datasource.driver-class-name=com.mysql.jdbc.Driver spring.datasource.type=com.alibaba.druid.pool.DruidDataSource spring.datasource.initialSize=5 spring.datasource.minIdle=5 spring.datasource.maxActive=20 spring.datasource.maxWait=60000mybatis.config-location=classpath:mybatis/mybatis-config.xml mybatis.mapper-locations=classpath:mybatis/mapper/*.xml http://localhost:7900/simple/1{"id":1,"username":"user1","name":"張三","age":20,"balance":100.00} 我們發現是可以正常訪問的,這樣一個非常簡單的用戶微服務我們已經寫完了DROP DATABASE IF EXISTS SpringCloud; create database SpringCloud; use SpringCloud;CREATE TABLE `user` (`id` bigint(20) NOT NULL,`username` varchar(40) DEFAULT NULL,`name` varchar(20) DEFAULT NULL,`age` int(3) DEFAULT NULL,`balance` decimal(10,2) DEFAULT NULL,PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;insert into user(id,username,name,age,balance) values(1,'user1','張三',20,100);insert into user(id,username,name,age,balance) values(2,'user2','李四',20,100);現在我們寫一下服務消費者,也就是這邊的movie項目,我們讓他比較簡單的去調用這個user,這個微服務,nohup java -jar microservice-simple-provider-user-0.0.1-SNAPSHOT.jar &sudo apt-get install iptablessudo aztech aztechsudo iptables -I INPUT -p tcp --dport 7900 -j ACCEPTsudo iptables-save10.40.8.152:7900/simple/1微服務服務之間是有自治的,所以我們啟動movie也是OK的,即使User沒有啟動好,啟動user也是OK的,restTemplate有問題,因為我們沒有new,我們在啟動類上加一點小小的配置@Bean public RestTemplate restTemplate() {return new RestTemplate(); }@Bean會把實例化的RestTemplate以方法名去命名,他的名稱是restTemplate,啟動7901,也就是movie這個微服務localhost:7901/movie/1 <?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.learn</groupId><artifactId>microservice-simple-consumer-movie</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>microservice-simple-consumer-movie</name><description>Demo project for Spring Boot</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.12.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></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project> #debug=true server.port=7901user.userServicePath: http://10.40.8.152:7900/simple/ package com.learn.cloud.entity;import java.math.BigDecimal;public class User {private Long id;private String username;private String name;private Short age;private BigDecimal balance;public Long getId() {return this.id;}public void setId(Long id) {this.id = id;}public String getUsername() {return this.username;}public void setUsername(String username) {this.username = username;}public String getName() {return this.name;}public void setName(String name) {this.name = name;}public Short getAge() {return this.age;}public void setAge(Short age) {this.age = age;}public BigDecimal getBalance() {return this.balance;}public void setBalance(BigDecimal balance) {this.balance = balance;}} package com.learn.cloud.controller;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.client.RestTemplate;import com.learn.cloud.entity.User;@RestController public class MovieController {@Autowiredprivate RestTemplate restTemplate;@Value("${user.userServicePath}")private String userServicePath;@GetMapping("/movie/{id}")public User findById(@PathVariable Long id) {return this.restTemplate.getForObject(this.userServicePath + id, User.class);} } package com.learn.cloud;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.Bean; import org.springframework.web.client.RestTemplate;@SpringBootApplication public class MicroserviceSimpleConsumerMovieApplication {@Beanpublic RestTemplate restTemplate() {return new RestTemplate();}public static void main(String[] args) {SpringApplication.run(MicroserviceSimpleConsumerMovieApplication.class, args);} } 是可以正常請求到user服務的,是可以用到user服務的接口的,同時寫了一個服務消費者,我們總結一下需要注意點,首先是服務提供者,第一個是@GetMapping,它是一個組合注解,是Spring4.3給我們提供的一個注解,yml是有嚴格的縮進的,可以是兩個空格縮進,也可以是四個空格縮進,然后回到movie這個項目,@Bean注解,我們用方法名稱,作為實例化后的Bean的名稱@Bean public RestTemplate restTemplate() {return new RestTemplate(); }相當于RestTemplate restTemplate = new RestTemplate();目前這個架構其實是存在很多問題的,我現在是在消費的這一側,把這個硬編碼了,在傳統的一些項目里面,大概沒有太多的問題了,因為這些環境都是比較固定的,IP端口都是比較固定的,但是在現在這種新式的環境下,就不一樣了,比如說docker,在一些云環境里面,IP和端口往往是動態的,當我把provider-user部署好了之后,他的IP和端口往往是動態的,那這個時候我們怎么去進行一個配置呢,加上我provider重新的進行上限,他的IP進行了變更,那這邊怎么樣去玩呢,所以硬編碼是行不通的,但是即使這樣也不行@Value("${user.userServicePath}") private String userServicePath;user.userServicePath: http://10.40.8.152:7900/simple/當然變得好維護了一些,當他的IP和端口發生了變化的時候,我這邊也要重新的配置,重新的啟動,當他又為其它的服務提供服務,那別的服務是不是也得改配置,這種維護量是很大的,這是第一個問題,第二個問題,movie微服務調用user微服務,當然它是提供者,現在這種情況是直接調,但是他有一定的問題,當我有多個提供的節點的時候,我怎么做到負載,中間加Nginx,由Nginx完成轉發,但是我們要知道,在一個復雜的項目里面,幾百個微服務,甚至上萬個,這都是有可能的,像亞馬遜光首頁,700個微服務,那是不是只要有服務調用的時候,就加個nginx,那這個也是非常的難管理,那怎么去解決目前的這種問題呢

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