# 1.Feign介绍




![image.png](/static/img/6ce56e37e890a10f6d89a6c509ad4cc7.image.webp)
# 2.定义和使用客户端
   ## (1)引入依赖
   
![image.png](/static/img/401192c64c830db97e495dce267f3287.image.webp)

```config

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
```
   ## (2)在order-service的启动类中加注释开启Fegin的功能
   
![image.png](/static/img/b9d4e7609cf614ea34849eeeb1f72892.image.webp)
   ## (3)编写Feign客户端
   
![image.png](/static/img/91fcbe5e62a20c13603cc5a69a980cbb.image.webp)

![image.png](/static/img/a84e48bdc4b91bf4e32b0fb8e565abb4.image.webp)

```java
package cn.itcast.order.clients;


import org.springframework.cloud.openfeign.FeignClient;

@FeignClient("userservice")
public interface UserClient {
}
```
## (4)调用举例

```java
@Service
public class OrderService {

    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private UserClient userClient;

    public Order queryOrderById(Long orderId) {
        // 1.查询订单·
        Order order = orderMapper.findById(orderId);
        
        User user = userClient.getUserById(order.getUserId());
        
        order.setUser(user);
        // 4.返回
        return order;
    }
}
```
# 3.配置feign
法一
![image.png](/static/img/030f9d4c9e50819516f8e857674b757b.image.webp)
法二
![image.png](/static/img/444b464a7cdfa0fea434bfd5c59eade1.image.webp)
# 4.feign性能优化
默认使用URLconnection
使用连接池代替URLconnection
![image.png](/static/img/74b12e1c38ed52ef1dc301d808f4ef37.image.webp)
连接池配置
![image.png](/static/img/95b8089089660df394b7c46cbcd175e2.image.webp)

```pom

        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-httpclient</artifactId>
        </dependency>
```

```config
feign:
  client:
    config:
      default:
        loggerLevel: FULL
  httpclient:
    enabled: true # 开启feign对httpclient的支持
    max-connections: 200 # 最大连接数
    max-connections-per-route: 50 # 每个路径的最大连接数
```
总结

![image.png](/static/img/f3605acba9227a3cb5aea5e1aca2edb6.image.webp)
# 5.feign的最佳实现

![image.png](/static/img/c107bb7e8e57c76310c9087330792d67.image.webp)
抽取具体实现
## （1）创建module

![image.png](/static/img/c51456bc900bc69c1bba3ac192fa49aa.image.webp)
## （2）将pojo和cliens的代码移动到feign-api中

![image.png](/static/img/41093267c68ad955916ec466070a0b0d.image.webp)
![image.png](/static/img/52f6b835c75a3822373600117d5886b9.image.webp)

Feign

# Nacos相关设置
## 1.权限配置


![image.png](/static/img/da99d2b0def0b3cb87fd5f5182a00dc9.image.webp)
在nacos中修改服务器权重如果为0则不访问
## 2.环境隔离

![image.png](/static/img/33600d8464bb99402c8118ee3134190e.image.webp)
![image.png](/static/img/9108aff8b549a3aca93573b26b1a3029.image.webp)
![image.png](/static/img/e5bc6c9faee42dbe8b1eef1b4e3e52d2.image.webp)
每一个namespace都有一个唯一id  
![image.png](/static/img/871a332ef755e496833b80e9d429f14d.image.webp)
不同namespace无法访问
## 3.nacos配置管理
### (1)统一配置管理
实现配置更改热更新
![image.png](/static/img/be686c67806135231a77ad6cdda367ca.image.webp)
![image.png](/static/img/a75c3967bfdfd2778f8df9ab2c601497.image.webp)
![image.png](/static/img/c1b38a06eed0c4259c070d1ad8643aa1.image.webp)
引入依赖
![image.png](/static/img/935a59db453ce409eb73626c372d6692.image.webp)

```config

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
        </dependency>
```
编写引导文件
![image.png](/static/img/acee28a0dbac57a1f46f7dd0ed700a81.image.webp)
### (2)配置热更新
![image.png](/static/img/c531647828c091f73a23f2dfeaeb060d.image.webp)
![image.png](/static/img/dfe8aa2994aa07e813d51a210e1b6d7d.image.webp)

Nacos相关设置

## 1.认识Nacos



![image.png](/static/img/56a5b62ba901b5d3a48ac5d14a3fc3b8.image.webp)
## 2.安装Nacos
### (1)访问github官网下载Nacos安装包

![image.png](/static/img/801dfe9e64ce81e1a49df9068c13929e.image.webp)
### (2)解压安装包到全英文的目录下

![image.png](/static/img/e790784019453e0c25c5eb37e135435e.image.webp)
<br>
nacos默认的配置文件在conf下的application.properties默认端口是8848
### (3)启动Nacos
进入bin目录显示4个文件

![image.png](/static/img/fb8dac00019a961615fb056666b150e1.image.webp)
### (4)代码中导入nacos依赖

```config

            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.5.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
```
### (5)代码中导入nacos客户端依赖

```config
<dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
 </dependency>
```
### (6)客户端添加yml配置文件

```config
spring:
#    nacos 配置
  cloud:
    nacos:
      server-addr: localhost:80
```
### (7)nacos集群划分
添加yml文件

```config
#    nacos 配置
  cloud:
    nacos:
      server-addr: localhost:80
      discovery:
        cluster-name: HZ
```
集群效果
![image.png](/static/img/774974f00b032105f423eba363d9f934.image.webp)
### (8)实现优先访问本地集群
修改yml中的规则

```config
userservice:
  ribbon:
    NFLoadBalancerRuleClassName: com.alibaba.cloud.nacos.ribbon.NacosRule
```

Nacos注册中心

### 1.通过IRule实现修改负载均衡规则



![image.png](/static/img/4b100f0290b6f5a42cf8148efbfa9a40.image.webp)

```java
@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }

    @Bean
    public IRule randomRule(){
        return new RandomRule();
    }
}
```
### 2.饥饿加载

![image.png](/static/img/fab608c523985b326c56b7459fbfc2f5.image.webp)

```config
ribbon:
  eager-load:
    enabled: true #开启饥饿加载
    clients:  # 指定饥饿加载的服务名称
      - userservice
```

配置Ribbon负载均衡

# **eurek**


## (1)搭建eureka注册中心

### 1.引入eureka注册中心的依赖
![](https://qianxiaojie.xyz/static/img/fa505c62de190b8e0515cd70dff12ebc.image.webp)

```pom
<dependency>
           <groupId>org.springframework.cloud</groupId>
           <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
```
### 2.编写启动类添加@EnableEurekaServer注解
![](https://qianxiaojie.xyz/static/img/073c41ef142568c6aa2952da985b5ecb.image.webp)
### 3.添加application.yml文件

```config
server:
  port: 10086
spring:
  application:
    name: eurekaserver
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka
```
## (2)注册服务(user-server)
### 1.在user-server服务中引入依赖

```pom
<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
```
### 2.在user-sever的application.yml中添加配置

```config
spring:
  application:
    name: userservice
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka
```
### 3.启动全部服务查看eureka中是否显示

![image.png](/static/img/29a27e7bf79444a65cfc142299af1a17.image.webp)
## (3)在order-server中实现服务拉取
### 1.使用服务名称代替服务ip和端口

```java
@GetMapping("{orderId}")
    public Order queryOrderByUserId(@PathVariable("orderId") Long orderId) {
        // 根据id查询订单并返回
        Order order = orderService.queryOrderById(orderId);
        // 利用RestTemplate发送http请求
        String url = "http://userservice/user/"+order.getUserId();
        User user = restTemplate.getForObject(url, User.class);
        // 封装User
        order.setUser(user);
        return order;
    }
```
### 2.实现负载均衡

![image.png](/static/img/61da44de69699ff9fd443c6f3c74be26.image.webp)

```java
@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}
```