Spring Cloud Alibaba 学习笔记(3)

声明式HTTP客户端-Feign

首先，三板斧：

依赖

        
            org.springframework.cloud
            spring-cloud-starter-openfeign

配置：无
注释：无

启动类中代码如下：

@SpringBootApplication
@MapperScan("com.zstu")
@EnableFeignClients
public class ContentCenterApplication {

    public static void main(String[] args) {

        SpringApplication.run(ContentCenterApplication.class, args);
    }

    //在spring容器中，创建一个对象，类型RestTemplate，名称是restTemplate()
    //
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

}

下面是更改的代码：

public class ShareService {
    private final ShareMapper shareMapper;
    private final UserCenterFeignClient userCenterFeignClient;
    public ShareDTO findById(Integer id) {
        Share share = this.shareMapper.selectByPrimaryKey(id);
        //获取发布人的id
        Integer userId = share.getUserId();

        UserDTO userDTO = this.userCenterFeignClient.findById(userId);


        //拿到用户中心的所有实例信息

        //怎么调用用户微服务的/users/{userId}?

        //消息的装配
        ShareDTO shareDTO = new ShareDTO();
        BeanUtils.copyProperties(share, shareDTO);
        shareDTO.setWxNickname(userDTO.getWxNickname());

        return shareDTO;
    }

package com.zstu.contentcenter.feignclient;

import com.zstu.contentcenter.domain.dto.user.UserDTO;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;


@FeignClient(name = "user-center")
public interface UserCenterFeignClient {
    
    @GetMapping("/users/{id}")
    UserDTO findById(@PathVariable Integer id);

}

feign打印日志：

logging:
  level: 
    com.zstu: debug

java代码实现配置日志

logging:
  level:
    com.zstu.contentcenter.feignclient.UserCenterFeignClient: debug

package com.zstu.contentcenter.feignclient;

import com.zstu.contentcenter.configuration.UserCenterFeignConfiguration;
import com.zstu.contentcenter.domain.dto.user.UserDTO;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;


@FeignClient(name = "user-center", configuration = UserCenterFeignConfiguration.class)

public interface UserCenterFeignClient {
    
    @GetMapping("/users/{id}")
    UserDTO findById(@PathVariable Integer id);

}

package com.zstu.contentcenter.configuration;

import feign.Logger;
import org.springframework.context.annotation.Bean;


public class UserCenterFeignConfiguration {
    @Bean
    public Logger.Level level() {
        //让feign打印所有请求的细节
        return Logger.Level.FULL;
    }
}

我们测试一下，发现打印日志了

这里我们需要有一个注意点

package com.zstu.contentcenter.configuration;

import feign.Logger;
import org.springframework.context.annotation.Bean;


@configuration
public class UserCenterFeignConfiguration {
    @Bean
    public Logger.Level level() {
        //让feign打印所有请求的细节
        return Logger.Level.FULL;
    }
}

这里加上了configuration后，会造成父子上下文的重复扫描，去除或者移动文件到启动类扫描不到的文件下

使用配置实现相同的日志效果

feign:
  client:
    config:
      #想要调用的微服务的名称
      user-center:
        loggerLevel: full

package com.zstu.contentcenter.feignclient;

import com.zstu.contentcenter.configuration.UserCenterFeignConfiguration;
import com.zstu.contentcenter.domain.dto.user.UserDTO;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;


//@FeignClient(name = "user-center", configuration = UserCenterFeignConfiguration.class)
@FeignClient(name = "user-center")

public interface UserCenterFeignClient {
    
    @GetMapping("/users/{id}")
    UserDTO findById(@PathVariable Integer id);

}

我们测试一下，发现也一样打印日志

feign的全局配置

代码配置

@EnableFeignClients(defaultConfiguration = GlobalFeignConfiguration.class)

属性配置

feign:
  client:
    config:
      #全局配置
      default:
        loggerLevel: full

package com.zstu.contentcenter;

import com.zstu.contentcenter.configuration.GlobalFeignConfiguration;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
import tk.mybatis.spring.annotation.MapperScan;

@SpringBootApplication
@MapperScan("com.zstu")
@EnableFeignClients//(defaultConfiguration = GlobalFeignConfiguration.class)

public class ContentCenterApplication {

    public static void main(String[] args) {

        SpringApplication.run(ContentCenterApplication.class, args);
    }

    //在spring容器中，创建一个对象，类型RestTemplate，名称是restTemplate()
    //
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

}

属性配置总结

> Ribbon 和 Feign的比较

优先级：
全局代码<全局属性<细粒度代码<细粒度属性
尽量使用一种属性配置

多参数请求构造：

方法1

    @GetMapping("/q")
    public User query(User user) {
        return user;
    }

    @Autowired
    private TestUserCenterFeignClient testUserCenterFeignClient;

    @GetMapping("/test-get")
    public UserDTO query(UserDTO userDTO) {
        return testUserCenterFeignClient.query(userDTO);
    }



package com.zstu.contentcenter.feignclient;

import com.zstu.contentcenter.domain.dto.user.UserDTO;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;


@FeignClient(name = "user-center")

public interface TestUserCenterFeignClient {
    @GetMapping("/q")
    UserDTO query(UserDTO userDTO);
}


  main:
    allow-bean-definition-overriding: true
 #
 这里我们需要注意点额一点是，为什么需要加上这么一段配置？
 因为下图，两个接口中，我都使用了@FeignClient(name = "user-center")，使用了两个接口，而且同名了，出了问题

    @Autowired
    private TestUserCenterFeignClient testUserCenterFeignClient;

    @GetMapping("/test-get")
    public UserDTO query(UserDTO userDTO) {
        return testUserCenterFeignClient.query(userDTO);
    }

	@FeignClient(name = "user-center")

	public interface TestUserCenterFeignClient {
   	 	@GetMapping("/q")
    	UserDTO query(@SpringQueryMap UserDTO userDTO);
	}

这里参考学习大目老师视频中的手记http://www.imooc.com/article/289000

方法2

@FeignClient(name = "microservice-provider-user")
public interface UserFeignClient {
  @RequestMapping(value = "/get", method = RequestMethod.GET)
  public User get1(@RequestParam("id") Long id, @RequestParam("username") String username);
}

Feign脱离Ribbon使用方式

    @Autowired
    private TestBaiduFeignClient testBaiduFeignClient;
    @GetMapping("/baidu")
    public String baiduIndex() {
        return this.testBaiduFeignClient.index();
    }

package com.zstu.contentcenter.feignclient;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;


//注意，这里分name = xxx，不可以省略，但是可以自定义，不然不可以启动
@FeignClient(name = "baidu", url = "http://www.baidu.com")
public interface TestBaiduFeignClient {
    @GetMapping("")
    String index();
}

feign连接池
三板斧：

依赖：

        
            io.github.openfeign
            feign-httpclient

配置

feign:
  client:
    config:
      #全局配置
      default:
        loggerLevel: full
  httpclient:
    enabled: true
    #feign的最大连接数
    max-connections: 200
    #feign单个路劲的最大连接数
    max-connections-per-route: 50
#让feign使用Apache httpclient做请求，而不是默认的urlconnection
#feign底层不仅支持URL connection 还支持Apache httpclient ，还支持okhttp

        
            io.github.openfeign
            >feign-okhttp
            10.1.0
        
        
          
          
 okhttp:
    enabled: true

#如果使用okhttp，则需要将别的enable删除

feign常见问题：http://www.imooc.com/article/289005

keep moving~~

Spring Cloud Alibaba 学习笔记(3)

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