Retrofit添加header参数的几种方法。

（1）使用注解的方式

添加一个Header参数

public interface UserService {    
    @Headers("Cache-Control: max-age=640000")  
    @GET("/tasks")  
    Call<List<Task>> getTasks();  
}  

public interface UserService {    
    @Headers({  
        "Accept: application/vnd.yourapi.v1.full+json",  
        "User-Agent: Your-App-Name"  
    })  
    @GET("/tasks/{task_id}")  
    Call<Task> getTask(@Path("task_id") long taskId);  
}  

OkHttpClient.Builder httpClient = new OkHttpClient.Builder();    
httpClient.addInterceptor(new Interceptor() {    
    @Override  
    public Response intercept(Interceptor.Chain chain) throws IOException {  
        Request original = chain.request();  
  
        Request request = original.newBuilder()  
            .header("User-Agent", "Your-App-Name")  
            .header("Accept", "application/vnd.yourapi.v1.full+json")  
            .method(original.method(), original.body())  
            .build();  
  
        return chain.proceed(request);  
    }  
}  
  
OkHttpClient client = httpClient.build();    
Retrofit retrofit = new Retrofit.Builder()    
    .baseUrl(API_BASE_URL)  
    .addConverterFactory(GsonConverterFactory.create())  
    .client(client)  
    .build();  

public interface UserService {    
    @GET("/tasks")  
    Call<List<Task>> getTasks(@Header("Content-Range") String contentRange);  
}