一. 背景常识
有时候微服务须要提供给多个消费者, 而不通过的消费者可能心愿根据本身状况应用不同的协定. 另一方面, 有时候如果本来服务以 dubbo 协定提供服务, 然而为了调试或者监控不便, 咱们也提供 rest 协定.
本文示例服务者同时提供 dubbo 和 rest 协定. 应用的 dubbo 版本为 2.7.1, springboot 版本为 2.1.5.
为了实在地模仿不同微服务之间的调用, 本文将服务者和生产离开. 对应的我的项目有两个, 别离为dubboshop-inventory(服务者)和dubboshop-order(消费者). 其构造如下:
dubboshop-inventory (库存微服务. 这个我的项目次要演示服务提供者角色) |- dubbo-api: 蕴含服务接口和 DTO 对象. 打包成 `dubboshop-inventory:1.0.0-snapshot.jar`, 通过 `mvn install`到本地或者`mvn deploy`部署到私服, 在上面`dubboshop-order`我的项目中援用依赖. |- fun.faceless.dubboshop.comms.entity.Result.java |- fun.faceless.dubboshop.comms.entity.CommRetCode.java |- dubbo-provider: 服务接口具体实现类 |- fun.faceless.dubboshop.inventory.dubboprovider.DubboApplication.java |- fun.faceless.dubboshop.inventory.dubboprovider.impl.InventoryProviderImpl.java dubboshop-order (订单微服务) |- dubbo-provider: 订单服务的提供者, 同时是dubboshop-inventory服务的消费者. 这里次要演示其作为消费者的角色. |- fun.faceless.dubboshop.order.dubboprovider.impl.OrderProviderImpl.java二. 通用dubbo配置
本文两个我的项目都作为服务者, 也都反对dubbo和rest协定, 所以两者dubbo相干的依赖都蕴含以下几局部.
1) 首先引入通用 dubbo 依赖
<!-- Dubbo dependencies --><dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo-bom</artifactId> <type>pom</type></dependency><dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo</artifactId> <version>${dubbo.version}</version> <exclusions> <exclusion> <groupId>org.apache.thrift</groupId> <artifactId>libthrift</artifactId> </exclusion> </exclusions></dependency><dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo-spring-boot-starter</artifactId></dependency><!-- dubbo registry: zookeeper dependencies--><dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo-dependencies-zookeeper</artifactId> <version>2.7.1</version> <type>pom</type> <exclusions> <exclusion> <artifactId>log4j</artifactId> <groupId>log4j</groupId> </exclusion> <exclusion> <artifactId>slf4j-log4j12</artifactId> <groupId>org.slf4j</groupId> </exclusion> </exclusions></dependency>2) dubbo rest 依赖
<!-- for dubbo rest protocol --><dependency> <groupId>org.apache.dubbo</groupId> <artifactId>dubbo-rpc-rest</artifactId></dependency><!-- for dubbo rest protocol with tomcat server --><dependency> <groupId>org.apache.tomcat.embed</groupId> <artifactId>tomcat-embed-core</artifactId></dependency>三. 服务者(Provider)实现
3.1 服务接口定义 dubbo-api
1) 数据传输对象定义 Result.java:
留神肯定要定义默认构造函数和实现Serializable接口.
@Data@NoArgsConstructor@AllArgsConstructorpublic class Result implements Serializable { private static final long serialVersionUID = 1L; public static String SUCCESS_MSG = "SUCC"; public static String DEFAULT_FAIL_MSG = "FAIL"; private String code; private String msg; private String subCode; private String subMsg; private String sign; private Object data; private Result(String code, String msg, Object data) { this.code = code; this.msg = msg; this.data = data; this.subCode = ""; this.subMsg = ""; this.sign = ""; } /** * Return succ result with given data. * @return */ public static Result succ() { return new Result(CommRetCode.OK, SUCCESS_MSG, null); } /** * Return succ result with given data. * @param msg * @return */ public static Result succ(String msg) { return new Result(CommRetCode.OK, msg, null); } /** * Return failed result with given code, msg, and data * @param code * @param msg * @param data * @return */ public static Result fail(String code, String msg, Object data) { return new Result(code, msg, data); } // 其余省略...}2) 通用返回值 CommRetCode.java
package fun.faceless.dubboshop.comms.entity;public interface CommRetCode { /** 所有 ok */ public final static String OK = "00000"; // 其余省略...}3) 定义服务提供者接口API: InventoryProvider.java
留神 REST 相干的注解都放在接口类中.
package fun.faceless.dubboshop.inventory.dubboprovider;import javax.ws.rs.*;import fun.faceless.dubboshop.comms.entity.Result;import org.apache.dubbo.config.annotation.Service;import org.apache.dubbo.rpc.protocol.rest.support.ContentType;/** * Order Dubbo Service */@Service@Path("inventory")@Produces({ContentType.APPLICATION_JSON_UTF_8})@Consumes({ContentType.APPLICATION_JSON_UTF_8})public interface InventoryProvider { @GET @Path("hello") Result hello(); /** * 减扣商品库存 */ @POST @Path("debit") Result debit(@QueryParam("goodsId") int goodsId, @QueryParam("amount") int amount);}3.2 服务实现具体实现
本节示例 Inventory 微服务即库存服务提供者.
1) 提供的服务的具体实现类 InventoryProviderImpl.java
package fun.faceless.dubboshop.inventory.dubboprovider.impl;import fun.faceless.dubboshop.comms.entity.Result;import fun.faceless.dubboshop.inventory.dao.InventoryDao;import fun.faceless.dubboshop.inventory.dubboprovider.InventoryProvider;import lombok.extern.slf4j.Slf4j;import org.apache.dubbo.config.annotation.Service;import org.springframework.beans.factory.annotation.Autowired;@Slf4j@Servicepublic class InventoryProviderImpl implements InventoryProvider { @Autowired InventoryDao inventoryDao; @Override public Result hello() { return Result.succ("hello from inventory center"); } @Override public Result debit(int goodsId, int amount) { log.debug("debit() goodsId: {}", goodsId); log.debug("debit() amount: {}", amount); inventoryDao.debit(goodsId, amount); return Result.succ(); }}2) 服务启动类 DubboApplication.java
package fun.faceless.dubboshop.inventory.dubboprovider;import org.apache.dubbo.config.spring.context.annotation.EnableDubbo;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.context.annotation.ComponentScan;@SpringBootApplication@EnableDubbo@ComponentScan("fun.faceless.dubboshop.inventory")@MapperScan("fun.faceless.dubboshop.inventory.dao.mapper")public class DubboApplication { public static void main(String[] args) { SpringApplication.run(DubboApplication.class, args); }}3) 模块配置文件 application-dev.yaml.
多协定反对的配置次要蕴含:
dubbo.config.multiple = true: 开启多个 protocol 配置绑定.dubbo.protocols: 反对的 prottocols 列表.
# 此处省略我的项目其余配置...# ========= Dubbo Provider ==============dubbo: config: # 开启多个protocol配置绑定 multiple: true # 注册核心配置 registry: id: dubboshop-registry address: zookeeper://yyadmin:2181 group: dubboshop simplified: true application: name: dubboshop-inventory id: dubboshop-inventory logger: slf4j qos-enable: false qos-accept-foreign-ip: true qos-port: 22223 protocols: dubbo: name: dubbo port: 20882 server: netty4 rest: name: rest server: tomcat port: 8082 scan: # dubbo 服务提供者实现类所在包 base-packages: fun.faceless.dubboshop.inventory.dubboprovider四. 消费者(Consumer)实现
本节示例 Order 微服务即作为订单的模块的服务者, 同时作为下面库存(Inventory)的消费者. 本例重视消费者.
1) 在pom.xml中增加服务者api的依赖:
<!-- inter-project dependencies --><dependency> <groupId>fun.faceless.dubboshop.inventory</groupId> <artifactId>dubboapi</artifactId></dependency>2) 在 OderProviderImpl.java 中生产接口.
package fun.faceless.dubboshop.order.dubboprovider.impl;public class OrderProviderImpl implements OrderProvider { @Autowired private OrderDao orderDao; // 通过 protocol="dubbo" 或者 protocol="rest" 指定应用的协定 @Reference(protocol="dubbo") private InventoryProvider inventoryProvider; @Override public int createOrder(int userId, int goodsId, int orderCount) { // 调用服务接口 Result debitResult = inventoryProvider.debit(goodsId, orderCount); return this.saveOrder(userId, goodsId, orderCount); } // 省略其余代码...}五. 注意事项
5.1 返回值对象肯定要有 默认构造函数 并实现 Serializiable 接口.
@Data@NoArgsConstructor@AllArgsConstructorpublic class Result implements Serializable { private static final long serialVersionUID = 1L; // ...如果没有默认构造函数, 则在应用 rest protocol 时, 返回值无奈生产端反序列化. 生产端会报相似如下异样:
org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class fun.faceless.xxx.Result]: can not instantiate from JSON object (need to add/enable type information?)如果没有实现 Serializiable 接口, 则在应用 dubbo protocol 时, 服务提供者无奈失常序列化返回值. 服务 (provider) 端会报相似如下异样:
Caused by: org.apache.dubbo.remoting.RemotingException: Failed to send response: Response [id=2, version=2.0.2, status=20, event=false, error=null, result=RpcResult [result=Result(code=00000, msg=SUCC, subCode=, subMsg=, sign=, data=null), exception=null]], cause: java.lang.IllegalStateException: Serialized class fun.faceless.dubboshop.comms.entity.Result must implement java.io.Serializablejava.lang.IllegalStateException: Serialized class fun.faceless.dubboshop.comms.entity.Result must implement java.io.Serializable5.2 调试时批改依赖模块的代码, 留神及时install/deploy
如果批改公共我的项目, 或者服务提供者接口所在的module, 在 mvn install 或 mvn deploy 之后, 肯定也要记得再调用这些 module 的我的项目从新导入依赖, 否则会因为缓存, 即使重启消费者服务, 也杯水车薪.
5.3 REST 注解放到服务接口上
对于 rest protocol, 如果是将接口独自打包 (即不带实现类在包内) 提供给消费者. 那么须要将 JAX-RS 相干的注解放到接口上. 否则会报如下谬误:
RESTEASY004600: You must use at least one, but no more than one http method annotation on XXX这是因为 resteasy jax-rs 2客户端仿佛不间接承受实现类。要使其工作，必须创立一个正确正文的接口。示例接口注解:
// InventoryProvider.java, 在 `dubboshop-inventory`我的项目`dubbo-api`模块中, 独自公布给消费者应用.@Service@Path("inventory")@Produces({ContentType.APPLICATION_JSON_UTF_8})@Consumes({ContentType.APPLICATION_JSON_UTF_8})public interface InventoryProvider { @GET @Path("hello") Result hello(); /** * 减扣商品库存 */ @POST @Path("debit") Result debit(@QueryParam("goodsId") int goodsId, @QueryParam("amount") int amount);}对应的实现类如下:
// InventoryProviderImpl.java, 在 `dubboshop-inventory`我的项目`dubbo-provider`模块中, 与消费者无关.@Slf4j@Servicepublic class InventoryProviderImpl implements InventoryProvider { @Autowired InventoryDao inventoryDao; @Override public Result hello() { return Result.succ("hello from inventory center"); } @Override public Result debit(int goodsId, int amount) { inventoryDao.debit(goodsId, amount); return Result.succ(); }}5.4 生产端能够指定服务的服务形式
@Reference(protocol="dubbo")// 或 @Reference(protocol="rest")private InventoryProvider inventoryProvider;