Spring Cloud学习03--OpenFeign基本使用

OpenFeign功能：Feign是一种声明式、模板化的HTTP客户端。现在已升级为OpenFeign。基本使用方式如下。

1.修改02-customer项目

在pom文件中添加openfeign的引用：

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
<!--
    其他组件的引用
-->9 </dependencies>

修改02-customer的启动类，添加一个注解：

package com.yangasen;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class CustomerApplication {
    public static void main(String[] args) {
        SpringApplication.run(CustomerApplication.class,args);
    }
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

在02和03项目中添加lombok注解，并定义一个Customer类，：

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>

package com.yangasen.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Customer {

    private Integer id;

    private String name;

    private Integer age;
}

在02-customer中添加一个接口，用于映射03-search项目注册在EUREKA中注册的SEARCH服务：

package com.yangasen.client;

import com.yangasen.entity.Customer;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.*;

@FeignClient("SEARCH")
public interface SearchClient {
    @RequestMapping(method = RequestMethod.GET, value = "/search")
    String search();

    //单个参数时，推荐使用@PathVariable
    @RequestMapping(value = "/search/{id}",method = RequestMethod.GET)
    Customer findById(@PathVariable(value = "id") Integer id);

    //多个参数时，也可以采用@RequestParam，不要省略Value属性
    @RequestMapping(value="/getcustomer",method = RequestMethod.GET)
    Customer getCustomer(@RequestParam(value = "id") Integer id, @RequestParam(value = "name") String Name);

    //传递的参数比较复杂时，会采用POST的方式请求，传递对象时统一采用JSON格式发送，需要添加@RequestBody注解
    @RequestMapping(value = "/save",method = RequestMethod.GET)//自动转换为post请求 405
    Customer save(@RequestBody Customer customer);
}

其中第10、14、18、22行对应的是03-search中controller的action：

package com.yangasen.controller;

import com.yangasen.entity.Customer;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

@RestController
public class SearchController {

    @Value("${server.port}")
    private String port;

    @GetMapping("/search")
    public String search(){
        return "search:"+port;
    }


    @GetMapping("/search/{id}")
    public Customer findById(@PathVariable Integer id){
        return new Customer(1,"zhangsan",18);
    }

    @GetMapping("/getcustomer")
    public Customer getCustomer(@RequestParam Integer id,@RequestParam String name){
        return new Customer(id,name,18);
    }

    @PostMapping("/save")//自动转换为post请求 405
    public  Customer save(@RequestBody Customer customer){
        return customer;
    }
}

最后修改02-customer的controller，修改调用方式，通过spring获取接口的实例，直接调用实例的search()方法：

package com.yangasen.controller;

import com.netflix.discovery.EurekaClient;
import com.yangasen.client.SearchClient;
import com.yangasen.entity.Customer;
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.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class CustomerController {

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
    private EurekaClient eurekaClient;

    @Autowired
    private SearchClient searchClient;

    @GetMapping("/customer")
    public String customer(){
        String result = searchClient.search();
        return result;
    }

    @GetMapping("/search/{id}")
    public Customer findById(@PathVariable Integer id){
        return searchClient.findById(id);
    }

    @GetMapping("/getcustomer")
    public Customer findById(@RequestParam Integer id, @RequestParam String name){
        return searchClient.getCustomer(id,name);
    }

    @GetMapping("/save")//自动转换为post请求
    public  Customer save(Customer customer){
        return searchClient.save(customer);
    }
}

2.测试效果：

重启全部五个模块，可以得到与之前一样的效果。

访问：http://localhost:8080/customer

可轮询(权重)得到8081和8082的服务的响应。

访问：http://localhost:8080/search/1

访问：http://locahost:8080/getcustomer?id=1&name=xxx

访问：http://localhost:8080/save?id=1&name=xxx&age=10