dubbo 2.6.0 之后 支持rest访问格式

支持标准的 JAX-RS 请参阅相关文档

pom.xml 参照官方的jar版本

https://github.com/apache/incubator-dubbo/blob/master/dependencies-bom/pom.xml

    <properties>
        <resteasy_version>3.0.19.Final</resteasy_version>
        <servlet_version>3.1.0</servlet_version>
        <jetty_version>6.1.26</jetty_version>
        <validation_version>1.1.0.Final</validation_version>
        <hibernate_validator_version>5.4.1.Final</hibernate_validator_version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.18</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>2.6.1</version>
        </dependency>
        <dependency>
            <groupId>javax.ws.rs</groupId>
            <artifactId>javax.ws.rs-api</artifactId>
            <version>2.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>2.12.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.11</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.3</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-jaxrs</artifactId>
            <version>${resteasy_version}</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-client</artifactId>
            <version>${resteasy_version}</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-netty4</artifactId>
            <version>${resteasy_version}</version>
            <exclusions>
                <exclusion>
                    <groupId>io.netty</groupId>
                    <artifactId>netty-all</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-jdk-http</artifactId>
            <version>${resteasy_version}</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-jackson-provider</artifactId>
            <version>${resteasy_version}</version>
        </dependency>
        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-jaxb-provider</artifactId>
            <version>${resteasy_version}</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>${servlet_version}</version>
        </dependency>
        <dependency>
            <groupId>org.mortbay.jetty</groupId>
            <artifactId>jetty</artifactId>
            <version>${jetty_version}</version>
        </dependency>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>${validation_version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>${hibernate_validator_version}</version>
        </dependency>
    </dependencies>

User.java

package com.yiwugou.demo.dubbo.bean;

import java.io.Serializable;

import lombok.Data;

@Data
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    private String username;
    private String password;
}

dubbo-demo-provider.xml

    <context:annotation-config />
    <context:component-scan base-package="com.yiwugou.demo.dubbo" />

    <dubbo:application name="dubbo-demo-provider" />
    
    <dubbo:registry address="zookeeper://127.0.0.1:2181" />
    <dubbo:protocol name="dubbo" port="-1" host="127.0.0.1" />
    <dubbo:protocol name="rest" port="8080" />
    <!-- 代表两个协议都有 dubbo 和 rest，如果只要rest dubbo 协议删掉即可 -->

    <dubbo:service interface="com.yiwugou.demo.dubbo.service.UserService" ref="userService" />

UserService.java （JAX-RS 注解推荐加载接口处）

package com.yiwugou.demo.dubbo.service;

import javax.ws.rs.Consumes;
import javax.ws.rs.FormParam;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;

import com.yiwugou.demo.dubbo.bean.User;

@Path("users")
@Produces({ MediaType.APPLICATION_JSON })
public interface UserService {
    @GET
    @Path("get/{id}")
    public User get(@PathParam("id") Long id);

    @POST
    @Path("byjson")
    @Consumes({ MediaType.APPLICATION_JSON })
    public User byJson(User user);

    @POST
    @Path("byform")
    @Consumes({ MediaType.APPLICATION_FORM_URLENCODED })
    public User byForm(@FormParam("id") Long id, @FormParam("username") String username);

    @GET
    @Path("byquery")
    public User byQuery(@QueryParam("username") String username, @QueryParam("password") String password);
}

UserServiceImpl.java

package com.yiwugou.demo.dubbo.service;

import org.springframework.stereotype.Service;

import com.yiwugou.demo.dubbo.bean.User;

@Service("userService")
public class UserServiceImpl implements UserService {

    @Override
    public User get(Long id) {
        User user = new User();
        user.setUsername(id + "-get-username");
        user.setPassword(id + "-get-password");
        System.err.print(user);
        return user;
    }

    @Override
    public User byJson(User user) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public User byForm(Long id, String username) {
        User user = new User();
        user.setUsername(id + "-byForm-" + username);
        user.setPassword(id + "-byForm-password");
        System.err.print(user);
        return user;
    }

    @Override
    public User byQuery(String username, String password) {
        User user = new User();
        user.setUsername("byQuery-" + username);
        user.setPassword("byQuery-" + password);
        System.err.print(user);
        return user;
    }
}

rest 访问的路径和方法为

get 
http://127.0.0.1:8080/users/get/1234

post with body
http://127.0.0.1:8080/users/byjson
{
    username:"abcd",
    password:"1234"
}

post with form
http://127.0.0.1:8080/users/byform
username=abcd
password=1234
(html form)

get 
http://127.0.0.1:8080/users/byquery?username=abcd&password=1234

非dubbo 如何调用 dubbo-rest 以及如何负载均衡？

官方没有提供相应的rest-client，

1. 自己写client代码

访问zk node 节点 可以得到真实服务地址与端口信息列表 然后负载均衡
(进入zookeeper 运行命令 ls /dubbo/com.yiwugou.demo.dubbo.service.UserService/providers

rest://10.6.62.155:8080/com.yiwugou.demo.dubbo.service.UserService?anyhost=true&application=dubbo-demo-provider&dubbo=2.6.1&generic=false&interface=com.yiwugou.demo.dubbo.service.UserService&methods=get,byJson,byQuery,byForm&pid=1292&side=provider&timestamp=1523410526582,
rest://10.6.62.155:8081/com.yiwugou.demo.dubbo.service.UserService?anyhost=true&application=dubbo-demo-provider&dubbo=2.6.1&generic=false&interface=com.yiwugou.demo.dubbo.service.UserService&methods=get,byJson,byQuery,byForm&pid=5296&side=provider&timestamp=1523412396290, 
) 

2 建议使用第三方rest的负载均衡
如 nginx, yiwugou homer

dubbo 调用 dubbo-rest

照常即可 我们不需要关注里面的具体协议是 dubbo 还是 rest

dubbo 调用 非dubbo-rest

~1. 可以用java代码或者采用第三方rest-client
~2.需要根据提供的 rest服务以及返回参数 自己组装类和接口

例如，我们要调用如下的外部服务
http://api.foo.com/services/users/1001
http://api.foo.com/services/users/1002

获取不同ID的用户资料，返回格式是JSON

{
    "id": 1001,
    "name": "Larry"
}
我们可根据这些信息，编写服务接口和参数类即可：

@Path("users")
public interface UserService {
    @GET
    @Path("{id : \\d+}")
    @Produces({MediaType.APPLICATION_JSON})
    User getUser(@PathParam("id") Long id);
}
public class User implements Serializable {
    private Long id;
    private String name;
}
对于spring中的配置，因为这里的REST服务不是dubbo提供的，所以无法使用dubbo的注册中心，直接配置外部REST服务的url地址即可（如多个地址用逗号分隔）：

<dubbo:reference id="userService" interface="xxx.UserService" url="rest://api.foo.com/services/"/>

参考 dubbox 帮助文档