Feign实现生命试rest调用

OrderApp.java

package com.cookqq.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

/**
 * 订单服务
 *
 */
@SpringBootApplication
@EnableFeignClients
public class OrderApp 
{
	
    public static void main( String[] args )
    {
        SpringApplication.run(OrderApp.class, args);
    }
}

@EnableFeignClients注解，声明使用Feign

user.java

package com.cookqq.consumer.bean;

import java.math.BigDecimal;

public class User {

	private Long id;
	private String username;
	private String name;
	private Integer age;
	private BigDecimal balance;
	
	
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	public BigDecimal getBalance() {
		return balance;
	}
	public void setBalance(BigDecimal balance) {
		this.balance = balance;
	}
	
	
	
}

UserFeignClient.java

package com.cookqq.consumer.feign;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.cookqq.consumer.bean.User;

/**
 * provider-user项目微服务名称
 * @author conca
 *
 */
@FeignClient(name="provider-user")
public interface UserFeignClient {

	
	@RequestMapping(value="/{id}", method=RequestMethod.GET)
	public User findUserById(@PathVariable("id") Long id);
	
}

findUserById(@PathVariable Long id)方法如果去掉@PathVariable，findUserById(Long id)默认@RequestBody注解。RequestBody一定是包含在请求体中的，GET方式无法包含。Feign在GET请求包含RequestBody时强制转成了POST请求，而不是报错。

OrderController.java

package com.cookqq.consumer.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.cookqq.consumer.bean.User;
import com.cookqq.consumer.feign.UserFeignClient;

@RestController
public class OrderController {

	@Autowired
	private UserFeignClient userFeignClient;
	
	@GetMapping("/user/{id}")
	public User findUserById(@PathVariable Long id){
//		return this.restTemplate.getForObject("http://127.0.0.1:8000/"+id, User.class);
		
		
//		List<ServiceInstance> listInfo = discoveryClient.getInstances("provider-user");
//		if(listInfo.size()>0){
//			return this.restTemplate.getForObject(
//					listInfo.get(new Random().nextInt(listInfo.size())).getUri()+"/"+id, 
//					User.class);
//		}
		
//		return this.restTemplate.getForObject("http://provider-user/"+id, User.class);
		
		return userFeignClient.findUserById(id);
	}
	
}

RequestMapping代表映射的路径，使用GET,POST,PUT,DELETE方式都可以映射到该端点。GetMapping代表get方式。

SpringMVC中常用的请求参数注解有（@RequestParam,@RequestBody,@PathVariable）等。name被默认当做@RequestParam。形参String name由框架使用字节码技术获取name这个名称，自动检测请求参数中key值为name的参数，也可以使用@RequestParam(“name”)覆盖变量本身的名称。当我们在url中携带name参数或者form表单中携带name参数时，会被获取到。

application.yml

server:
  port: 8080
spring:
  application:
    name: consumer-order
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true

pom.xml

<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.cookqq</groupId>
  <artifactId>consumer-order-feign</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>consumer-order-feign</name>
  <url>http://maven.apache.org</url>

 <!-- 引入spring boot的依赖 -->
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.9.RELEASE</version>
  </parent>
  
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  
   <!-- 引入spring cloud的依赖 -->
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Edgware.RELEASE</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
</project>

feign依赖内容

<dependency>

      <groupId>org.springframework.cloud</groupId>

      <artifactId>spring-cloud-starter-openfeign</artifactId>

    </dependency>

启动euraka

启动provider-user（多个）

启动consumer-order-feign

多次访问，查看provider-user访问日志