【SpringCloud构建微服务系列】Feign的使用详解

一、简介

 在微服务中，服务消费者需要请求服务生产者的接口进行消费，可以使用SpringBoot自带的RestTemplate或者HttpClient实现，但是都过于麻烦。

 这时，就可以使用Feign了，它可以帮助我们更加便捷、优雅地调用HTTP API。

本文代码全部已上传至我的github，点击这里获取。

二、为服务消费者整合Feign

1.复制项目microservice-consumer-movie，并修改为microservice-consumer-movie-feign

2.pom文件添加依赖：

 

　　　　<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>

 

3.创建一个Feign接口，并添加@FeignClient注解

package cn.sp.client;  2 
import cn.sp.bean.User;  4 import org.springframework.cloud.netflix.feign.FeignClient;  5 import org.springframework.web.bind.annotation.GetMapping;  6 import org.springframework.web.bind.annotation.PathVariable;  7 
/**
 * @author ship 10  * @Description 11  * @Date: 2018-07-17 13:25 12  */
@FeignClient(name = "microservice-provider-user") 14 public interface UserFeignClient { 15 
    @GetMapping("/{id}") 17     User findById(@PathVariable("id") Long id); 18 }

@FeignClient注解中的microservice-provider-user是一个任意的客户端名称，用于创建Ribbon负载均衡器。

再这里，由于使用了Eureka，所以Ribbon会把microservice-provider-user解析为Eureka Server服务注册表中的服务。

4.Controller层代码

/**
 * 请求用户微服务的API  3  * Created by 2YSP on 2018/7/8.  4  */
@RestController  6 public class MovieController {  7 
 @Autowired  9     private UserFeignClient userFeignClient; 10 
    @GetMapping("/user/{id}") 12     public User findById(@PathVariable Long id){ 13         return userFeignClient.findById(id); 14  } 15 }

 

5.修改启动类，添加@EnableFeignClients注解

/**
 * 使用Feign进行声明式的REST Full API调用  3  */
@EnableFeignClients(basePackages = {"cn.sp.client"})  5 @EnableEurekaClient  6 @SpringBootApplication  7 public class MicroserviceConsumerMovieFeignApplication {  8 
    public static void main(String[] args) { 10         SpringApplication.run(MicroserviceConsumerMovieFeignApplication.class, args); 11  } 12 }

这里我添加了basePackages属性指定扫描的包，开始没添加报错了。

这样，电影微服务就可以调用用户微服务的API了。

1.启动microservice-discovery-eureka 

2.启动生产者microservice-provider-user

3.启动microservice-consumer-movie-feign

4.访问http://localhost:8010/user/1获得返回数据。

 

三、手动创建Feign

1.复制microservice-provider-user并修改artifactId为microservice-provider-user-with-auth

2.添加依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
 </dependency>

 3.代码部分

package cn.sp.conf;  2 
import org.springframework.beans.factory.annotation.Autowired;  4 import org.springframework.context.annotation.Bean;  5 import org.springframework.context.annotation.Configuration;  6 import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;  7 import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;  8 import org.springframework.security.config.annotation.web.builders.HttpSecurity;  9 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;  10 import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;  11 import org.springframework.security.core.GrantedAuthority;  12 import org.springframework.security.core.authority.SimpleGrantedAuthority;  13 import org.springframework.security.core.userdetails.UserDetails;  14 import org.springframework.security.core.userdetails.UserDetailsService;  15 import org.springframework.security.core.userdetails.UsernameNotFoundException;  16 import org.springframework.security.crypto.password.NoOpPasswordEncoder;  17 import org.springframework.security.crypto.password.PasswordEncoder;  18 import org.springframework.stereotype.Component;  19 
import java.util.ArrayList;  21 import java.util.Collection;  22 import java.util.List;  23 
/**
 * @author ship  26  * @Description  27  * @Date: 2018-07-18 09:51  28  */
@Configuration  30 @EnableWebSecurity  31 @EnableGlobalMethodSecurity(prePostEnabled = true)  32 public class WebSecurityConfig extends WebSecurityConfigurerAdapter{  33 
 @Autowired  35  CustomUserDetailService userDetailService;  36 
 @Override  38     protected void configure(AuthenticationManagerBuilder auth) throws Exception {  39         super.configure(auth);  40         auth.userDetailsService(userDetailService).passwordEncoder(this.passwordEncoder());  41  }  42 
 @Override  44     protected void configure(HttpSecurity http) throws Exception {  45         super.configure(http);  46         //所有请求都需要经过HTTP basic认证
 http.authorizeRequests().anyRequest().authenticated().and().httpBasic();  48  }  49 
 @Bean  51     public PasswordEncoder passwordEncoder(){  52         //明文编码器，这是一个不做任何操作的密码编码器，是Spring提供给我们做明文测试的
        return NoOpPasswordEncoder.getInstance();  54  }  55 
}  57 
@Component  59 class CustomUserDetailService implements UserDetailsService{  60     /**
 * 模拟两个账号：用户名user和用户名admin  62  * @param username  63  * @return
 * @throws UsernameNotFoundException  65      */
 @Override  67     public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {  68         if ("user".equals(username)){  69             return new SecurityUser("user","password1","user-role");  70         }else if ("admin".equals(username)){  71             return new SecurityUser("admin","password2","admin-role");  72  }  73         return null;  74  }  75 }  76 
class SecurityUser implements UserDetails{  78 
    private Long id;  80     private String username;  81     private String password;  82     private String role;  83 
    public SecurityUser(String username,String password,String role){  85         this.username = username;  86         this.password = password;  87         this.role = role;  88  }  89 
    public Long getId() {  91         return id;  92  }  93 
    public void setId(Long id) {  95         this.id = id;  96  }  97 
    public void setUsername(String username) {  99         this.username = username; 100  } 101 
    public void setPassword(String password) { 103         this.password = password; 104  } 105 

    public String getRole() { 108         return role; 109  } 110 
    public void setRole(String role) { 112         this.role = role; 113  } 114 
 @Override 116     public Collection<? extends GrantedAuthority> getAuthorities() { 117         List<GrantedAuthority> authorities = new ArrayList<>(); 118         SimpleGrantedAuthority authority = new SimpleGrantedAuthority(this.role); 119  authorities.add(authority); 120         return authorities; 121  } 122 
 @Override 124     public String getPassword() { 125         return this.password; 126  } 127 
 @Override 129     public String getUsername() { 130         return this.username; 131  } 132 
 @Override 134     public boolean isAccountNonExpired() { 135         return true; 136  } 137 
 @Override 139     public boolean isAccountNonLocked() { 140         return true; 141  } 142 
 @Override 144     public boolean isCredentialsNonExpired() { 145         return true; 146  } 147 
 @Override 149     public boolean isEnabled() { 150         return true; 151  } 152 }

package cn.sp.controller;  2 
import cn.sp.bean.User;  4 import cn.sp.service.UserService;  5 import org.slf4j.Logger;  6 import org.slf4j.LoggerFactory;  7 import org.springframework.beans.factory.annotation.Autowired;  8 import org.springframework.security.core.GrantedAuthority;  9 import org.springframework.security.core.context.SecurityContextHolder; 10 import org.springframework.security.core.userdetails.UserDetails; 11 import org.springframework.web.bind.annotation.GetMapping; 12 import org.springframework.web.bind.annotation.PathVariable; 13 import org.springframework.web.bind.annotation.RestController; 14 
import java.util.Collection; 16 
/**
 * Created by 2YSP on 2018/7/8. 19  */
@RestController 21 public class UserController { 22 
 @Autowired 24     private UserService userService; 25 
    private static final Logger log = LoggerFactory.getLogger(UserController.class); 27 



    @GetMapping("/{id}") 32     public User findById(@PathVariable Long id){ 33         Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal(); 34         if (principal instanceof UserDetails){ 35             UserDetails user = (UserDetails) principal; 36             Collection<? extends GrantedAuthority> authorities = user.getAuthorities(); 37             for (GrantedAuthority g : authorities){ 38                 //打印用户当前信息
                log.info("当前用户是:{},角色是:{}",user.getUsername(),g.getAuthority()); 40  } 41         }else { 42             //do other things
 } 44         return userService.findById(id); 45  } 46 }

4.测试修改后的用户服务

先启动microservice-discovery-eureka，再启动microservice-provider-user-with-auth，访问http://localhost:8000/1，即可弹出一个登录框，输入用户名和密码（user/password1和admin/password）才能获取结果。

5.修改电影服务，复制microservice-consumer-movie-feign并改为microservice-consumer-movie-feign-manual

6.去掉Feign接口的@FeignClient注解，去掉启动类的@EnableFeignClients注解

7.controller层代码修改如下。

/** * 请求用户微服务的API * Created by 2YSP on 2018/7/8. */ @Import(FeignClientsConfiguration.class) @RestController public class MovieController { private UserFeignClient userUserFeignClient; private UserFeignClient adminUserFeignClient; @Autowired public MovieController(Decoder decoder, Encoder encoder, Client client, Contract contract){ this.userUserFeignClient = Feign.builder().client(client).decoder(decoder).encoder(encoder) .contract(contract).requestInterceptor(new BasicAuthRequestInterceptor("user","password1")) .target(UserFeignClient.class,"http://microservice-provider-user/"); this.adminUserFeignClient = Feign.builder().client(client).decoder(decoder).encoder(encoder) .contract(contract).requestInterceptor(new BasicAuthRequestInterceptor("admin","password2")) .target(UserFeignClient.class,"http://microservice-provider-user/"); } @GetMapping("/user-user/{id}") public User findByIdUser(@PathVariable Long id){ return userUserFeignClient.findById(id); } @GetMapping("/user-admin/{id}") public User findByIdAdmin(@PathVariable Long id){ return adminUserFeignClient.findById(id); } }

8.启动microservice-consumer-movie-feign-manual，并访问http://localhost:8010/user-user/4获取结果同时看到用户微服务打印日志。

2018-07-18 14:19:06.320  INFO 14256 --- [nio-8000-exec-1] cn.sp.controller.UserController          : 当前用户是:user,角色是:user-role

访问http://localhost:8010/user-admin/4打印日志：

2018-07-18 14:20:13.772  INFO 14256 --- [nio-8000-exec-2] cn.sp.controller.UserController          : 当前用户是:admin,角色是:admin-role

四、Feign对继承的支持

Feign还支持继承，将一些公共操作弄到父接口，从而简化开发

比如，先写一个基础接口：UserService.java

 

public interface UserService { 2     @RequestMapping(method= RequestMethod.GET,value="/user/{id}") 3     User getUser(@PathVariable("id") long id); 4 }

服务提供者Controller：UserResource.java

@RestController 2 public class UserResource implements UserService { 3 
  //...
}

服务消费者：UserClient.java

@FeignClient("users") 2 public interface UserClient extends UserService { 3 }

虽然很方便但是官方不建议这样做。

五、Feign对压缩的支持

Feign还可以对传输的数据进行压缩，只需要在appllication.properties文件添加如下配置即可。

 

feign.compression.request.enable=true
feign.compression.response.enable=true
feign.compression.request.mime-types=text/xml,application/xml,application/json
feign.compression.request.min-request-size=2048

 

六、设置Feign的日志

1.复制项目microservice-consumer-movie-feign，修改为microservice-consumer-movie-feign-logging

2.编写Feign配置类

 

package cn.sp.conf;  2 
import feign.Logger;  4 import org.springframework.context.annotation.Bean;  5 import org.springframework.context.annotation.Configuration;  6 
/**
 * Created by 2YSP on 2018/7/18.  9  */
@Configuration 11 public class FeignLogConfiguration { 12 
    /**
 * NONE:不记录任何日志（默认） 15  * BASIC：仅记录请求方法、URL、响应状态代码以及执行时间 16  * HEADERS：记录BASIC级别的基础上，记录请求和响应的header 17  * FULL:记录请求和响应的header，body和元数据 18  * @return
     */
 @Bean 21  Logger.Level feignLoggerLevel(){ 22         return Logger.Level.FULL; 23  } 24 }

 

3.修改Feign，使用指定配置类

@FeignClient(name = "microservice-provider-user",configuration = FeignLogConfiguration.class) 2 public interface UserFeignClient { 3 
    @GetMapping("/{id}") 5     User findById(@PathVariable("id") Long id); 6 }

4.在application.yml中添加如下内容，设置日志级别，注意：Feign的日志打印只会对DEBUG级别做出响应

5测试：启动microservice-discovery-eureka，microservice-provider-user和microservice-consumer-movie-feign-logging，访问http://localhost:8010/user/1，可看到日志结果。

 

七、使用Feign构造多参数请求

当我们用Get请求多参数的URL的时候，比如：http://microservice-provider-user/get?id=1&username=zhangsan，可能会采取如下的方式

@FeignClient(name = "microservice-provider-user") 2 public interface UserFeignClient { 3 
    @RequestMapping(value = "/get",method = RequestMethod.GET) 5  User get0(User user); 6 
}

然而会报错，尽管指定了GET方法，Feign仍然会使用POST方法发起请求。

正确处理方式一：使用@RequestParam注解

 @RequestMapping(value = "/get",method = RequestMethod.GET) 2  User get1(@RequestParam("id") Long id,@RequestParam("username") String username);

但是这种方法也有个缺点，如果参数比较多就要写很长的参数列表。

正确处理方式二：使用map接收

 

 

@RequestMapping(value = "/get",method = RequestMethod.GET) 2 User get2(Map<String,Object> map);

 

处理方式三：如果请求方式没有限制的话，换成POST方式

 @RequestMapping(value = "/get",method = RequestMethod.POST) 2  User get3(User user);

排版比较乱敬请见谅，参考资料：SpringCloud与Docker微服务架构实战。