Retrofit 2.0 URL 使用細節

OKHttp + Retrofit 這一套網絡框架，幾乎是Android 網絡請求必備的，但是再運用retrofit 這個框架時，應該更加深入去了解相關的點。這篇文章就記錄自己對其理解和一些自己遇到的坑。

baseUrl 

拼接問題

Retrofit retrofit = new Retrofit.Builder()
                .client(builder.build())
                .baseUrl(url)
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .build();

通過 baseUrl（url），來確定網絡請求的公共部分url， 剩餘部分通過註解的方式進行拼接。假如我的公共url爲：http://www.sjh.com, 但是你清楚 baseUrl 寫成 

 .baseUrl ("http://www.sjh.com/api")  和 .baseUrl ("http://www.sjh.com/api/") 區別嗎？你清楚如何修改某個請求的baseUrl ?   

現在探討一下：

<b>Base URLs should always end in {@code /}.</b>
<p>
A trailing {@code /} ensures that endpoints values which are relative paths will correctly
append themselves to a base which has path components.
<p>
<b>Correct:</b><br>
Base URL: http://example.com/api/<br>
Endpoint: foo/bar/<br>
Result: http://example.com/api/foo/bar/
<p>
<b>Incorrect:</b><br>
Base URL: http://example.com/api<br>
Endpoint: foo/bar/<br>
Result: http://example.com/foo/bar/
<p>
This method enforces that {@code baseUrl} has a trailing {@code /}.
<p>
<b>Endpoint values which contain a leading {@code /} are absolute.</b>
<p>
Absolute values retain only the host from {@code baseUrl} and ignore any specified path
components.
<p>
Base URL: http://example.com/api/<br>
Endpoint: /foo/bar/<br>
Result: http://example.com/foo/bar/
<p>
Base URL: http://example.com/<br>
Endpoint: /foo/bar/<br>
Result: http://example.com/foo/bar/
<p>
<b>Endpoint values may be a full URL.</b>
<p>
Values which have a host replace the host of {@code baseUrl} and values also with a scheme
replace the scheme of {@code baseUrl}.
<p>
Base URL: http://example.com/<br>
Endpoint: https://github.com/square/retrofit/<br>
Result: https://github.com/square/retrofit/
<p>
Base URL: http://example.com<br>
Endpoint: //github.com/square/retrofit/<br>
Result: http://github.com/square/retrofit/ (note the scheme stays 'http')

上面是 baseUrl 方法的註釋，我們可以知道：

• baseUrl 最好以 / 結束，否則會忽略 url schme 後面的相對路徑，比如上面的例子中說的 api；

替換BaseUrl

假如，某個接口需要替換baseUrl ，而我們又不想寫一遍 httpClient ，我們可以通過這樣的方式來實現：

@GET 
Call<BaseResp<List<UserDiversionResp>>> getUserDiversion(@Url String fullUrl);

不在註解後面接 url， 只要在括號里加一個 @Url , 寫出url的全路徑即可。

提交文件

RequestBody faceApiKey = RequestBody.create(MediaType.parse("text/plain"), key);
RequestBody faceApiSecret = RequestBody.create(MediaType.parse("text/plain"), secret);

byte[] photos   photo 爲二進制字節流
RequestBody fileBody = RequestBody.create(MediaType.parse("image/jpeg"), photos);
MultipartBody.Part part = MultipartBody.Part.createFormData("selfie", "xxxx", fileBody);


facePresenter.uploadFrontFace(faceApiKey, faceApiSecret, part,
                new FaceHttpCallback<FaceFrontValidateModel>(mActivity, false) {
                    @Override
                    public void onSuccess(FaceFrontValidateModel result) {
                       
                            
                    }

                    @Override
                    public void onFailure(FaceHttpError error) {
  

                    }
                });
    }



 public void uploadFrontFace(@Part("api_key") RequestBody api_key, @Part("api_secret") RequestBody api_secret, @Part MultipartBody.Part file,
                                FaceHttpCallback<FaceFrontValidateModel> httpCallback) {
        Observable observable = FaceHttpClient.getInstance(false)
                .create(FaceService.class)
                .uploadFrontFace(api_key, api_secret, file);
        toSubscribe(observable).subscribe(httpCallback);



   //正臉驗證
    @POST("lite/raw/validate_front_face")
    @Multipart
    Observable<FaceFrontValidateModel> uploadFrontFace(@Part("api_key") RequestBody api_key,
                                                       @Part("api_secret") RequestBody api_secret,
                                                       @Part MultipartBody.Part face);

上傳文件時，需要把文件轉換爲字節流纔可以，並且根據其格式進行解析 RequestBody.create(MediaType.parse("image/jpeg"), photos)； 要想徹底搞清這些類型和一些參數，應該對http的原理有所瞭解，和最原始的get 、post 進行文件上傳的寫法及原理，可以參考 get 、post 請求