SpringCloud使用Feign实现服务调用

spring cloud feign简介

spring cloud feign也是一个基础工具类，它整合了spring cloud ribbon和spring cloud hystrix，除了提供这两者的强大功能以外，它还提供了一种声明式的web服务客户端定义方式。使用它可以进行服务的消费，但是它的客户端负载平衡仍是通过ribbon实现的

使用spring cloud feign

创建一个springboot工程，作为服务调用方

1.pom.xml

<dependency>
  <groupid>org.springframework.boot</groupid>
  <artifactid>spring-boot-starter-web</artifactid>
 </dependency>

 <dependency>
  <groupid>org.springframework.cloud</groupid>
  <artifactid>spring-cloud-starter-eureka</artifactid>
 </dependency>
 <dependency>
  <groupid>org.springframework.cloud</groupid>
  <artifactid>spring-cloud-starter-feign</artifactid>
 </dependency>

 <dependency>
  <groupid>org.springframework.boot</groupid>
  <artifactid>spring-boot-starter-test</artifactid>
  <scope>test</scope>
</dependency>

spring-cloud-starter-feign加入了feign的依赖

2.启动类

@enablefeignclients
@enablediscoveryclient
@springbootapplication
public class feignconsumerapplication {

 public static void main(string[] args) {
  springapplication.run(feignconsumerapplication.class, args);
 }
}

@enablefeignclients：开启spring cloud feign的支持功能

3.服务层

@feignclient("hello-service")
 public interface helloservice {

 @requestmapping(value = "/hello", method = requestmethod.get)
 string hello();
}

@feignclient(“hello-service”)：制定服务名来绑定服务

注：服务名不区分大小写

@requestmapping：指定调用服务中的具体方法

4.controller层

@controller
public class consumercontroller {

 @autowired
 private helloservice helloservice;

 @requestmapping(value = "/feign-consumer", method = requestmethod.get)
 @responsebody
 public string helloconsumer() {
  return helloservice.hello();
 }
}

在方法中调用这个绑定了hello-service服务接口的客户端向该服务发起/hello接口的调用

5.配置类

server.port=9001

spring.application.name=feign-consumer
eureka.client.serviceurl.defaultzone=http://localhost:1111/eureka/

启动程序以后，在浏览器中输入http://localhost:9001/feign-consumer出现下图：

- 提升使用，带参数的请求
在具体业务中的接口会比之前程序的复杂得多，这里介绍一下feign对集中不同形式参数的绑定方法。有@requestparam、@requestheader、@requestbody

1.改造服务提供类的service层，添加几个方法

@requestmapping(value = "/hello1", method = requestmethod.get)
@responsebody
public string hello(@requestparam string name) {
 return "hello " + name;
}

@requestmapping(value = "/hello2", method = requestmethod.get)
@responsebody
public user hello(@requestheader string name, @requestheader integer age) {
 return new user(name, age);
}

@requestmapping(value = "/hello3", method = requestmethod.post)
@responsebody
public string hello(@requestbody user user) {
 return "hello " + user.getname() + ", " + user.getage();
}

2.添加一个javabean

public class user {
 private string name;
 private integer age;

 public user() {
 }

 public user(string name, integer age) {
  this.name = name;
  this.age = age;
 }

 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;
 }

 @override
 public string tostring() {
  return "user{" +
    "name='" + name + '\'' +
    ", age=" + age +
    '}';
 }
}

3.修改服务调用类的接口

@requestmapping(value = "/hello1", method = requestmethod.get)
string hello(@requestparam("name") string name);

@requestmapping(value = "/hello2", method = requestmethod.get)
user hello(@requestheader("name") string name, @requestheader("age") integer age);

@requestmapping(value = "/hello3", method = requestmethod.post)
string hello(@requestbody user user);

这里在定义各参数绑定时@requestparam、@requestheader等可以指定参数名称的注解，但它们的value不能少，否则会报错，这和springmvc中有一点不同

4.在服务调用类controller层添加一个测试的接口

 @requestmapping(value = "/feign-consumer2", method = requestmethod.get)
 @responsebody
 public string helloconsumer2() {
  string s2 = helloservice.hello("dayday");
  return s2;
 }

启动以后访问浏览器：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。