书接上文，之前的代码使用字符串拼接的方式构造我们调用的 URL，目前这个 URL 有一个参数，如果有很多参数，我们就需要构造一个哈希表，URL 上面挂满了&参数连接符
Feign 是 Netflix 开发的声明式、模板化的 HTTP 客户端，帮助我们更加优雅的调用 HTTP API。
集成 Feign
我们再 movie 微服务里面集成 Feign，首先添加依赖
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> <version>1.3.5.RELEASE</version> </dependency>
之后我们需要构造一个接口，这个接口是专门处理掉 HTTP API 的
为了方便，这里建一个 feign 包，在这个包下面建立一个接口UserFeignClient，用来调用用户接口的 feign REST 接口
package cn.ts.ms.movie.feign;import org.springframework.cloud.netflix.feign.FeignClient;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import cn.ts.ms.movie.model.User;@FeignClient(name="MS-SIMPLE-PROVIDER-USER")public interface UserFeignClient { @RequestMapping(value="/user/find?id={id}",method=RequestMethod.GET) public User findById(@PathVariable("id") Integer id);
}说明：@FeignClient(name="MS-SIMPLE-PROVIDER-USER")标明是向 user 这个未付发起请求的；
在 requestMapping 里面构造了请求路径，合在一起就是 user 微服务的 HTTP 调用；这里的 REST 格式不正确，姑且先走通程序。
接下来在 Controller 里面调用 feign 来进行数据请求
@RestControllerpublic class MovieController { @Autowired
private RestTemplate restTemplate; @Autowired
private LoadBalancerClient loadBalancerClient; @Autowired
private UserFeignClient userFeignClient;
@GetMapping("/user/{id}") public User findByUserId(@PathVariable Integer id){ //return restTemplate.getForObject("http://MS-SIMPLE-PROVIDER-USER/user/find?id="+id, User.class);
return userFeignClient.findById(id);
}
@GetMapping("/log") public void printLog(){
ServiceInstance instance = loadBalancerClient.choose("MS-SIMPLE-PROVIDER-USER");
System.out.println("Now:"+instance.getServiceId()+"---"+instance.getHost()+":"+instance.getPort());
}
}接下来修改启动类，增加@EnableFeignClients 注解
@SpringBootApplication@EnableEurekaClient@EnableFeignClientspublic class MsSimpleConsumerMovieApplication { @Bean
@LoadBalanced
public RestTemplate restTemplate(){ return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(MsSimpleConsumerMovieApplication.class, args);
}
}测试和启动
启动 eureka1和 eureka2以及两个 user，最后启动 movie
从浏览器里面访问
不仅仅如此，我们的请求是分别随机请求到 user 的两个微服务，也就是实现的负载均衡
自定义 Feign
实际应用开发过程中，上面的例子是不能使用的，用户接口需要账号才能访问，而且不同用户访问结果不一样才行
下面就来修改之前的微服务达到这个目的
首先修改用户微服务
增加security 的依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency>
接下来我们就需要配置 security 的配置类，关于 Spring security将在后续介绍，这里直接引入他人的基本配置
package cn.ts.ms.user;import java.util.ArrayList;import java.util.Collection;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.core.GrantedAuthority;import org.springframework.security.core.authority.SimpleGrantedAuthority;import org.springframework.security.core.userdetails.UserDetails;import org.springframework.security.core.userdetails.UserDetailsService;import org.springframework.security.core.userdetails.UsernameNotFoundException;import org.springframework.security.crypto.password.NoOpPasswordEncoder;import org.springframework.security.crypto.password.PasswordEncoder;import org.springframework.stereotype.Component;@Configuration@EnableWebSecurity@EnableGlobalMethodSecurity(prePostEnabled=true)public class WebSecurityConfigurer extends WebSecurityConfigurerAdapter{ @Override
protected void configure(HttpSecurity http) throws Exception { //所有请求都需要经过 HTTP Basic 认证
http.authorizeRequests().anyRequest().authenticated().and().httpBasic();
}
@Bean
public PasswordEncoder passwordEncoder(){ return NoOpPasswordEncoder.getInstance();
}
@Autowired
private CustomerUserDetailsService userDetailsService;
@Override
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
auth.userDetailsService(userDetailsService).passwordEncoder(this.passwordEncoder());
}
@Component
class CustomerUserDetailsService implements UserDetailsService { //构造用户，可以查询数据库来完成
@Override
public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException { if("user".equals(username)){ return new SecurityUser("user","123","role");
}else if("admin".equals(username)){ return new SecurityUser("admin","123","admin");
} return null;
}
}
class SecurityUser implements UserDetails{ private static final long serialVersionUID = 1L; public SecurityUser() {}
public SecurityUser(String name,String password,String role) { this.name=name; this.password=password; this.role=role;
}
private Integer id; private String name; private String password; private String role;
//手机用户的角色列表
@Override
public Collection<? extends GrantedAuthority> getAuthorities() {
Collection<GrantedAuthority> authorities=new ArrayList<>();
SimpleGrantedAuthority role=new SimpleGrantedAuthority(this.role);
authorities.add(role); return authorities;
} @Override
public String getPassword() { return this.password;
} @Override
public String getUsername() { return this.name;
} @Override
public boolean isAccountNonExpired() {//账号没有过期
return true;
} @Override
public boolean isAccountNonLocked() {//账号没有被锁
return true;
} @Override
public boolean isCredentialsNonExpired() {//凭证没有失效
return true;
} @Override
public boolean isEnabled() {//开启状态
return true;
}
}
}接下来在控制层修改一下代码
package cn.ts.ms.user.controller;import java.util.Collection;import javax.annotation.Resource;import org.springframework.boot.autoconfigure.EnableAutoConfiguration;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.RequestMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;import cn.ts.ms.user.mapper.UserMapper;import cn.ts.ms.user.model.User;@RestController @RequestMapping("/user")
@EnableAutoConfiguration public class UserController { @Resource
private UserMapper userMapper;
@RequestMapping("/find")
public User findUserById(@RequestParam String id){
Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal(); if(principal instanceof UserDetails){
UserDetails userDetails=(UserDetails)principal;
Collection<? extends GrantedAuthority> authorities = userDetails.getAuthorities(); for(GrantedAuthority auth:authorities){
System.out.println("当前用户："+userDetails.getUsername()+" 拥有角色"+auth.getAuthority());
}
}
System.out.println("=================================="); return userMapper.findUserById(id);
}
}在浏览器里面访问 user 微服务接口，看到需要登录
输入 user/123 或者 admin/123 可以进入正常浏览
接下来修改电影微服务
去掉UserFeignClient的注解；
去掉启动类的 EnableFeign的注解
修改 Controller 类如下
package cn.ts.ms.movie.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.cloud.client.ServiceInstance;import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;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 org.springframework.web.client.RestTemplate;import cn.ts.ms.movie.feign.UserFeignClient;import cn.ts.ms.movie.model.User;import feign.Client;import feign.Contract;import feign.Feign;import feign.auth.BasicAuthRequestInterceptor;import feign.codec.Decoder;import feign.codec.Encoder;@Import(FeignClientsConfiguration.class)@RestControllerpublic class MovieController { @Autowired
private RestTemplate restTemplate; @Autowired
private LoadBalancerClient loadBalancerClient;// @Autowired// private UserFeignClient userFeignClient;
private UserFeignClient userUserFeignClient;
private UserFeignClient adminUserFeignClient;
@Autowired
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","123"))
.target(UserFeignClient.class,"http://MS-SIMPLE-PROVIDER-USER/"); this.adminUserFeignClient=Feign.builder().client(client).encoder(encoder).decoder(decoder).contract(contract)
.requestInterceptor(new BasicAuthRequestInterceptor("admin","123"))
.target(UserFeignClient.class,"http://MS-SIMPLE-PROVIDER-USER/");
}
@GetMapping("/user-user/{id}") public User fingByUserIdWithUser(@PathVariable Integer id){ return this.userUserFeignClient.findById(id);
}
@GetMapping("/user-admin/{id}") public User fingByUserIdWithAdmin(@PathVariable Integer id){ return this.adminUserFeignClient.findById(id);
}
// @GetMapping("/user/{id}")// public User findByUserId(@PathVariable Integer id){// //return restTemplate.getForObject("http://MS-SIMPLE-PROVIDER-USER/user/find?id="+id, User.class);// return userFeignClient.findById(id);// }
@GetMapping("/log") public void printLog(){
ServiceInstance instance = loadBalancerClient.choose("MS-SIMPLE-PROVIDER-USER");
System.out.println("Now:"+instance.getServiceId()+"---"+instance.getHost()+":"+instance.getPort());
}
}再次访问 movie 的接口，用不同的 URL，可以发现在user 微服务打印的日志不一样http://127.0.0.1:8010/user-user/1对应的日志当前用户：user 拥有角色rolehttp://127.0.0.1:8010/user-admin/1对应的日志当前用户：admin 拥有角色admin
Feign 支持压缩功能，在 yml 配置里面增加对应的配置即可,版本不同配置不一样貌似。
Feign 的多参数问题
1、在接口入参的地方，每个接口参数对应一个请求参数；
2、配置 map 表传递到接口
Post 请求多参数，直接使用@RequestBody 注解类来进行，Feign 接口也同样使用即可
作者：breezedancer
链接：https://www.jianshu.com/p/04218c285a73
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