使用Feign实现声明式REST调用

6.1. Feign简介

Feign是一个声明式的REST客户端，它的目的就是让REST调用更加简单。

Feign提供了HTTP请求的模板，通过编写简单的接口和插入注解，就可以定义好HTTP请求的参数、格式、地址等信息。

而Feign则会完全代理HTTP请求，我们只需要像调用方法一样调用它就可以完成服务请求及相关处理。

SpringCloud对Feign进行了封装，使其支持SpringMVC标准注解和HttpMessageConverters。

Feign可以与Eureka和Ribbon组合使用以支持负载均衡。

6.2. 为服务消费者整合Feign

pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<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.</modelVersion>

    <artifactId>microservice-consumer-movie-feign</artifactId>

    <packaging>jar</packaging>

    <parent>

        <groupId>com.itmuch.cloud</groupId>

        <artifactId>microservice-spring-cloud</artifactId>

        <version>0.0.-SNAPSHOT</version>

    </parent>

    <properties>

        <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>

        <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>

        <java.version>1.8</java.version>

    </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-eureka</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

        </dependency>

        <dependency>

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

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

        </dependency>

    </dependencies>

</project>

Feign类

package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import com.itmuch.cloud.entity.User;

@FeignClient("microservice-provider-user")

public interface UserFeignClient {

  @RequestMapping(value = "/simple/{id}", method = RequestMethod.GET)

    //@GetMapping("/simple/{id}")

  public User findById(@PathVariable("id") Long id); // 两个坑：1. @GetMapping不支持   2. @PathVariable得设置value

}

图文：

6.3. 自定义Feign配置

Spring Cloud允许通过注解@FeignClient的configuration属性自定义Feign的配置，自定义配置的优先级比FeignClientsConfiguration要高。

pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<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.</modelVersion>

    <artifactId>microservice-consumer-movie-feign-customizing</artifactId>

    <packaging>jar</packaging>

    <parent>

        <groupId>com.itmuch.cloud</groupId>

        <artifactId>microservice-spring-cloud</artifactId>

        <version>0.0.-SNAPSHOT</version>

    </parent>

    <properties>

        <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>

        <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>

        <java.version>1.8</java.version>

    </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-eureka</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

        </dependency>

        <dependency>

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

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

        </dependency>

    </dependencies>

</project>

配置文件

spring:

  application:

    name: microservice-consumer-movie-feign-customizing

server:

  port:

eureka:

  client:

    healthcheck:

      enabled: true

    serviceUrl:

      defaultZone: http://user:password123@localhost:8761/eureka

  instance:

    prefer-ip-address: true

logging:

  level:

    com.itmuch.cloud.feign.UserFeignClient: DEBUG

# 解决第一次请求报超时异常的方案：

# hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds:

# 或者：

# hystrix.command.default.execution.timeout.enabled: false

# 或者：

feign.hystrix.enabled: false ## 索性禁用feign的hystrix支持

# 超时的issue：https://github.com/spring-cloud/spring-cloud-netflix/issues/768

# 超时的解决方案： http://stackoverflow.com/questions/27375557/hystrix-command-fails-with-timed-out-and-no-fallback-available

# hystrix配置： https://github.com/Netflix/Hystrix/wiki/Configuration#execution.isolation.thread.timeoutInMilliseconds

config

package com.itmuch.config;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import feign.Contract;

@Configuration

public class FooConfiguration {

  @Bean

  public Contract feignContract() {

    return new feign.Contract.Default();

  }

}

实体

package com.itmuch.cloud.entity;

import java.math.BigDecimal;

public class User {

  private Long id;

  private String username;

  private String name;

  private Short age;

  private BigDecimal balance;

  public Long getId() {

    return this.id;

  }

  public void setId(Long id) {

    this.id = id;

  }

  public String getUsername() {

    return this.username;

  }

  public void setUsername(String username) {

    this.username = username;

  }

  public String getName() {

    return this.name;

  }

  public void setName(String name) {

    this.name = name;

  }

  public Short getAge() {

    return this.age;

  }

  public void setAge(Short age) {

    this.age = age;

  }

  public BigDecimal getBalance() {

    return this.balance;

  }

  public void setBalance(BigDecimal balance) {

    this.balance = balance;

  }

}

Feign

package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;

import com.itmuch.cloud.entity.User;

import com.itmuch.config.FooConfiguration;

import feign.Param;

import feign.RequestLine;

@FeignClient(name = "microservice-provider-user", configuration = FooConfiguration.class)

public interface UserFeignClient {

  @RequestLine("GET /simple/{id}")

  public User findById(@Param("id") Long id);

}

Controller

package com.itmuch.cloud.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.itmuch.cloud.entity.User;

import com.itmuch.cloud.feign.UserFeignClient;

@RestController

public class MovieController {

  @Autowired

  private UserFeignClient userFeignClient;

  @GetMapping("/movie/{id}")

  public User findById(@PathVariable Long id) {

    return this.userFeignClient.findById(id);

  }

}

启动类

package com.itmuch.cloud;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

import org.springframework.cloud.netflix.feign.EnableFeignClients;

@SpringBootApplication

@EnableEurekaClient

@EnableFeignClients

public class ConsumerMovieFeignApplication {

  public static void main(String[] args) {

    SpringApplication.run(ConsumerMovieFeignApplication.class, args);

  }

}

注意，我们在此类中修改了Feign的Contract ，那么Contract 是什么呢。它叫做契约。因为Feign一开始使用的契约是SpringMVC，所以刚才我们SpringMVC的注解的时候直接成功了，但是你如果现在启动项目你就会发现已经启动不了了。因为Contract.Default()使用的契约是Feign自己的，也就是说我们要把SpringMVC的注解修改为Feign的注解

SpringMVC版本

@GetMapping (value = "/user/getUser/{id}") public User getUser(@PathVariable("id")Long id);

Feign版本

@RequestLine("GET /user/getUser/{id}") public User getUser(@Param("id") Long id);

6.4. 手动创建Feign

服务端：

pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<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.</modelVersion>

    <artifactId>microservice-provider-user-with-auth</artifactId>

    <packaging>jar</packaging>

    <name>microservice-provider-user-with-auth</name>

    <description>Demo project for Spring Boot</description>

    <parent>

        <groupId>com.itmuch.cloud</groupId>

        <artifactId>microservice-spring-cloud</artifactId>

        <version>0.0.-SNAPSHOT</version>

    </parent>

    <properties>

        <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>

        <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>

        <java.version>1.8</java.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-data-jpa</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

        </dependency>

        <dependency>

            <groupId>com.h2database</groupId>

            <artifactId>h2</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

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

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

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-security</artifactId>

        </dependency>

    </dependencies>

</project>

配置文件：

server:

  port:

spring:

  jpa:

    generate-ddl: false

    show-sql: true

    hibernate:

      ddl-auto: none

  datasource:

    platform: h2

    schema: classpath:schema.sql

    data: classpath:data.sql

  application:

    name: microservice-provider-user-with-auth

logging:

  level:

    root: INFO

    org.hibernate: INFO

    org.hibernate.type.descriptor.sql.BasicBinder: TRACE

    org.hibernate.type.descriptor.sql.BasicExtractor: TRACE

    com.itmuch: DEBUG

eureka:

  client:

    healthcheck:

      enabled: true

    serviceUrl:

      defaultZone: http://user:password123@localhost:8761/eureka

  instance:

    prefer-ip-address: true

    instance-id: ${spring.application.name}:${spring.cloud.client.ipAddress}:${spring.application.instance_id:${server.port}}

    metadata-map:

      zone: ABC      # eureka可以理解的元数据

      lilizhou: BBC  # 不会影响客户端行为

    lease-renewal-interval-in-seconds:

Spring Security的配置类

package com.itmuch.cloud.entity;

import org.springframework.security.core.GrantedAuthority;

import org.springframework.security.core.authority.SimpleGrantedAuthority;

import org.springframework.security.core.userdetails.UserDetails;

import java.util.ArrayList;

import java.util.Collection;

public class SecurityUser implements UserDetails {

    private static final long serialVersoinUID = 1L;

    private Long id;

    private String username;

    private String password;

    private String role;

    public SecurityUser() {

    }

    public SecurityUser(String username, String password, String role) {

        this.username = username;

        this.password = password;

        this.role = role;

    }

    @Override

    public Collection<? extends GrantedAuthority> getAuthorities() {

        Collection<GrantedAuthority> authorities = new ArrayList<GrantedAuthority>();

        SimpleGrantedAuthority authority = new SimpleGrantedAuthority(this.role);

        authorities.add(authority);

        return authorities;

    }

    @Override

    public String getPassword() {

        return password;

    }

    @Override

    public String getUsername() {

        return username;

    }

    @Override

    public boolean isAccountNonExpired() {

        return true;

    }

    @Override

    public boolean isAccountNonLocked() {

        return true;

    }

    @Override

    public boolean isCredentialsNonExpired() {

        return true;

    }

    @Override

    public boolean isEnabled() {

        return true;

    }

    public Long getId() {

        return id;

    }

    public void setId(Long id) {

        this.id = id;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public void setPassword(String password) {

        this.password = password;

    }

    public String getRole() {

        return role;

    }

    public void setRole(String role) {

        this.role = role;

    }

}

package com.itmuch.cloud.microserviceprovideruserwithauth.security;

import org.springframework.security.core.userdetails.UserDetails;

import org.springframework.security.core.userdetails.UserDetailsService;

import org.springframework.security.core.userdetails.UsernameNotFoundException;

import org.springframework.stereotype.Component;

@Component

public class CustomUserDetailsService implements UserDetailsService {

    /**

     * 模拟两个账户

     * ① 账号是user，密码是password1，角色是user-role

     * ② 账号时候admin，密码是password1，角色是admin-role

     * @param username

     *                  用户名

     * @return

     *

     * @throws UsernameNotFoundException

     */

    @Override

    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {

        if ("user".equals(username)) {

            return new SecurityUser("user", "password1", "user-role");

        } else if ("admin".equals(username)) {

            return new SecurityUser("admin", "password2", "admin-role");

        } else {

            return null;

        }

    }

}

package com.itmuch.cloud.microserviceprovideruserwithauth.security;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;

import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;

import org.springframework.security.config.annotation.web.builders.HttpSecurity;

import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;

import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

import org.springframework.security.crypto.password.NoOpPasswordEncoder;

import org.springframework.security.crypto.password.PasswordEncoder;

@Configuration

@EnableWebSecurity

@EnableGlobalMethodSecurity(prePostEnabled = true)

public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired

    private CustomUserDetailsService userDetailsService;

    @Override

    protected void configure(HttpSecurity http) throws Exception {

        // 所有的请求，都需要经过HTTP basic认证

        http

            .authorizeRequests()

                .anyRequest().authenticated()

                .and()

                .httpBasic();

    }

    @Bean

    public PasswordEncoder passwordEncoder() {

        // 明文编码器。这个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();

    }

    @Override

    protected void configure(AuthenticationManagerBuilder auth) throws Exception {

        auth.userDetailsService(this.userDetailsService).passwordEncoder(this.passwordEncoder());

    }

}

修改Controller，在其中打印当前登录的用户信息

package com.itmuch.cloud.controller;

import com.itmuch.cloud.repository.UserRepository;

import com.itmuch.cloud.entity.User;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.security.core.GrantedAuthority;

import org.springframework.security.core.context.SecurityContextHolder;

import org.springframework.security.core.userdetails.UserDetails;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RestController;

import java.util.Collection;

@RestController

public class UserController {

    private static final Logger LOGGER = LoggerFactory.getLogger(UserController.class);

    @Autowired

    private UserRepository userRepository;

    @GetMapping("/{id}")

    public User findById(@PathVariable Long id) {

        Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();

        if (principal instanceof UserDetails) {

            UserDetails user = (UserDetails) principal;

            Collection<? extends GrantedAuthority> collections = user.getAuthorities();

            for (GrantedAuthority ga: collections) {

                // 打印当前登录用户的信息

                UserController.LOGGER.info("当前用户是{}, 角色是{}", user.getUsername(), ga.getAuthority());

            }

        } else {

            UserController.LOGGER.warn("ε=(´ο｀*)))唉，出现问题了");

        }

        User findOne = userRepository.findOne(id);

        return findOne;

    }

}

客服端：

pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<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.</modelVersion>

    <artifactId>microservice-consumer-movie-feign-manual</artifactId>

    <packaging>jar</packaging>

    <parent>

        <groupId>com.itmuch.cloud</groupId>

        <artifactId>microservice-spring-cloud</artifactId>

        <version>0.0.-SNAPSHOT</version>

    </parent>

    <properties>

        <project.build.sourceEncoding>UTF-</project.build.sourceEncoding>

        <project.reporting.outputEncoding>UTF-</project.reporting.outputEncoding>

        <java.version>1.8</java.version>

    </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-eureka</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

        </dependency>

        <dependency>

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

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

        </dependency>

    </dependencies>

</project>

配置文件

spring:

  application:

    name: microservice-consumer-movie-feign-manual

server:

  port:

eureka:

  client:

    healthcheck:

      enabled: true

    serviceUrl:

      defaultZone: http://user:password123@localhost:8761/eureka

  instance:

    prefer-ip-address: true

ribbon:

  eureka:

    enabled: true

实体类

package com.itmuch.cloud.entity;

import java.math.BigDecimal;

public class User {

  private Long id;

  private String username;

  private String name;

  private Short age;

  private BigDecimal balance;

  public Long getId() {

    return this.id;

  }

  public void setId(Long id) {

    this.id = id;

  }

  public String getUsername() {

    return this.username;

  }

  public void setUsername(String username) {

    this.username = username;

  }

  public String getName() {

    return this.name;

  }

  public void setName(String name) {

    this.name = name;

  }

  public Short getAge() {

    return this.age;

  }

  public void setAge(Short age) {

    this.age = age;

  }

  public BigDecimal getBalance() {

    return this.balance;

  }

  public void setBalance(BigDecimal balance) {

    this.balance = balance;

  }

}

Feign类

package com.itmuch.cloud.feign;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import com.itmuch.cloud.entity.User;

public interface UserFeignClient {

  @RequestMapping(value = "/{id}", method = RequestMethod.GET)

  public User findById(@PathVariable("id") Long id);  

}

package com.itmuch.cloud.controller;

import com.itmuch.cloud.feign.UserFeignClient;

import com.itmuch.cloud.entity.User;

import feign.Client;

import feign.Contract;

import feign.Feign;

import feign.auth.BasicAuthRequestInterceptor;

import feign.codec.Decoder;

import feign.codec.Encoder;

import org.springframework.cloud.netflix.feign.FeignClientsConfiguration;

import org.springframework.context.annotation.Import;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RestController;

@Import(FeignClientsConfiguration.class) // Spring Cloud为Feign默认提供的配置类

@RestController

public class MovieController {

    private UserFeignClient userUserFeignClient;

    private UserFeignClient adminUserFeignClient;

    public MovieController(Decoder decoder, Encoder encoder, Client client, Contract contract) {

        this.userUserFeignClient = Feign.builder().client(client).encoder(encoder).decoder(decoder).contract(contract)

                .requestInterceptor(new BasicAuthRequestInterceptor("user", "password1"))

                .target(UserFeignClient.class, "http://microservice-provider-user-with-auth/");

        this.adminUserFeignClient = Feign.builder().client(client).encoder(encoder).decoder(decoder).contract(contract)

                .requestInterceptor(new BasicAuthRequestInterceptor("admin", "password2"))

                .target(UserFeignClient.class, "http://microservice-provider-user-with-auth/");

    }

    @GetMapping("/user-user/{id}")

    public User findByIdUser(@PathVariable Long id) {

        return this.userUserFeignClient.findById(id);

    }

    @GetMapping("/user-admin/{id}")

    public User findByIdAdmin(@PathVariable Long id) {

        return this.adminUserFeignClient.findById(id);

    }

}

图文：

6.5. 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 {

     @RequestMapping(method=RequestMethod.GET,value="/user/{id}")

      User getUser(@PathVariable("id") long id);

}

服务提供者Controller：UserResource.java

@RestController

 public class UserResource implements UserService {

 //...

 }

服务消费者：UserClient.java

 @FeignClient("users")

       public interface UserClient extends UserService {

}

6.6. Feign对压缩的支持

feign:

  compression:

      mime-types: text/xml,application/xml,application/json

  request:

       enable: true

       min-request-size:

  response:

        enable: true

6.7. Feign的日志

Feign配置类

package com.itmuch.cloud.conf;

import feign.Logger;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

  /**

   * Created by 2YSP on 2018/7/18.

   */

 @Configuration

 public class FeignLogConfiguration {

     /**

      * NONE:不记录任何日志（默认）

      * BASIC：仅记录请求方法、URL、响应状态代码以及执行时间

      * HEADERS：记录BASIC级别的基础上，记录请求和响应的header

      * FULL:记录请求和响应的header，body和元数据

      * @return

      */

     @Bean

     Logger.Level feignLoggerLevel(){

         return Logger.Level.FULL;

    }

 }

修改Feign，使用指定配置类

package com.itmuch.cloud.feign;

import org.springframework.cloud.netflix.feign.FeignClient;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import com.itmuch.cloud.conf.FeignLogConfiguration;

import com.itmuch.cloud.entity.User;

@FeignClient( name = "microservice-provider-user",configuration = FeignLogConfiguration.class)

public interface UserFeignClient {

  @RequestMapping(value = "/simple/{id}", method = RequestMethod.GET)

    //@GetMapping("/simple/{id}")

  public User findById(@PathVariable("id") Long id); // 两个坑：1. @GetMapping不支持   2. @PathVariable得设置value

  @RequestMapping(value = "/user", method = RequestMethod.POST)

  public User postUser(@RequestBody User user);

  // 该请求不会成功，只要参数是复杂对象，即使指定了是GET方法，feign依然会以POST方法进行发送请求。可能是我没找到相应的注解或使用方法错误。

  // 如勘误，请@lilizhou2008  eacdy0000@126.com

  @RequestMapping(value = "/get-user", method = RequestMethod.GET)

  public User getUser(User user);

}

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

spring:

  application:

    name: microservice-consumer-movie-feign

server:

  port:

eureka:

  client:

    healthcheck:

      enabled: true

    serviceUrl:

      defaultZone: http://user:password123@localhost:8761/eureka

  instance:

    prefer-ip-address: true

logging:

  level:

    com.itmuch.cloud.feign.UserFeignClient: DEBUG

6.8. 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")

 public interface UserFeignClient {

     @RequestMapping(value = "/get",method = RequestMethod.GET)

     User get0(User user);

 }

正确处理方式一：使用@RequestParam注解

 @RequestMapping(value = "/get",method = RequestMethod.GET)

  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)

 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)

 User get3(User user);

巴特西

6.使用Feign实现声明式REST调用

使用Feign实现声明式REST调用

6.1. Feign简介

Feign是一个声明式的REST客户端，它的目的就是让REST调用更加简单。

Feign提供了HTTP请求的模板，通过编写简单的接口和插入注解，就可以定义好HTTP请求的参数、格式、地址等信息。

而Feign则会完全代理HTTP请求，我们只需要像调用方法一样调用它就可以完成服务请求及相关处理。

SpringCloud对Feign进行了封装，使其支持SpringMVC标准注解和HttpMessageConverters。

Feign可以与Eureka和Ribbon组合使用以支持负载均衡。

6.2. 为服务消费者整合Feign

6.3. 自定义Feign配置

Spring Cloud允许通过注解@FeignClient的configuration属性自定义Feign的配置，自定义配置的优先级比FeignClientsConfiguration要高。

SpringMVC版本

@GetMapping (value = "/user/getUser/{id}") public User getUser(@PathVariable("id")Long id);

Feign版本

@RequestLine("GET /user/getUser/{id}") public User getUser(@Param("id") Long id);

6.4. 手动创建Feign

服务端：

客服端：

6.5. Feign对继承的支持

6.6. Feign对压缩的支持

6.7. Feign的日志

6.8. 使用Feign构造多参数请求

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