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Retrofit 2.0 詳解（一）基本用法
Retrofit 2.0 詳解（二）加載https請(qǐng)求

接下來(lái)我們講解一下怎么通過(guò)Retrofit 來(lái)個(gè)傳輸中的報(bào)文加密莫鸭，老規(guī)矩选侨，還是先寫Service接口

    @POST("NewsServlet")
    Observable<String> testInterceptor(@Body News news);

關(guān)鍵點(diǎn)就是怎么把news這個(gè)對(duì)象的json字符串加密追他，那就需要用到攔截器了Interceptor菩浙，不知道的老鐵還是自行百度吧狂秦，下面咱們看下怎么通過(guò)Interceptor來(lái)給報(bào)文加解密的。

第一步蜻展，就要實(shí)現(xiàn)Interceptor接口锥忿，重寫Response intercept(Chain chain)方法

public class EncryptInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {
        Request request = chain.request();
        //這個(gè)是請(qǐng)求的url虚吟，也就是咱們前面配置的baseUrl
        String url = request.url().toString();
        //這個(gè)是請(qǐng)求方法
        String method = request.method();
        long t1 = System.nanoTime();
        request = encrypt(request);//模擬的加密方法
        Response response = chain.proceed(request);
        long t2 = System.nanoTime();
        response = decrypt(response);
        return response;
    }
}

下面咱們看下加密方法是怎么寫的

    //加密
    private Request encrypt(Request request) throws IOException {
        //獲取請(qǐng)求body寸认，只有@Body 參數(shù)的requestBody 才不會(huì)為 null
        RequestBody requestBody = request.body();
        if (requestBody != null) {
            okio.Buffer buffer = new okio.Buffer();
            requestBody.writeTo(buffer);
            Charset charset = Charset.forName("UTF-8");
            MediaType contentType = requestBody.contentType();
            if (contentType != null) {
                charset = contentType.charset(charset);
            }
            
            String string = buffer.readString(charset);
            //模擬加密的方法，這里調(diào)用大家自己的加密方法就可以了
            String encryptStr = encrypt(string);
                RequestBody body = MultipartBody.create(contentType, encryptStr);
                request = request.newBuilder()
                        .post(body)
                        .build();
            
        }
        return request;
    }

咱們看下String string = buffer.readString(charset);這個(gè)string讀出來(lái)的是什么

{"comments":[],"date":"20170619","id":1,"likes":"likes","title":"Converter用法3","views":"views"}

其實(shí)就是把news轉(zhuǎn)換成了json字符串

下面看下我隨便寫的加密方法串慰，前面隨便加個(gè)"我是密文："

    //模擬加密的方法
    private String encrypt(String string) {
        return "我是密文：" + string;
    }

在看下服務(wù)器收到的報(bào)文

我是密文：{"comments":[],"date":"20170619","id":1,"likes":"likes","title":"Converter用法3","views":"views"}

下面就是服務(wù)解密做邏輯處理了偏塞，做完處理服務(wù)器在給客戶端響應(yīng)的時(shí)候也續(xù)要加密返回和客戶端，下面來(lái)看下客戶端是怎么解密的

    private Response decrypt(Response response) throws IOException {
        if (response.isSuccessful()) {
            //the response data
            ResponseBody body = response.body();
            BufferedSource source = body.source();
            source.request(Long.MAX_VALUE); // Buffer the entire body.
            Buffer buffer = source.buffer();
            Charset charset = Charset.defaultCharset();
            MediaType contentType = body.contentType();
            if (contentType != null) {
                charset = contentType.charset(charset);
            }
            String string = buffer.clone().readString(charset);
            //解密方法邦鲫，需要自己去實(shí)現(xiàn)
            String bodyString = decrypt(string);
            ResponseBody responseBody = ResponseBody.create(contentType, bodyString);
            response = response.newBuilder().body(responseBody).build();
        }
        return response;
    }

后來(lái)響應(yīng)的報(bào)文

我是密文：{"comments":[],"date":"20170619","id":1,"likes":"likes","title":"Converter用法3","views":"views"}

我這邊的解密方法和也很簡(jiǎn)單

    //模擬解密的方法
    private String decrypt(String string) {
        if (string != null && string.length() != 0) {
            string.replace("我是密文：", "");
        }
        return string;
    }

第二步添加Interceptor

 OkHttpClient.Builder builder = new OkHttpClient().newBuilder();
 builder.addInterceptor(new EncryptInterceptor());
 Retrofit retrofit = new Retrofit.Builder()
         .baseUrl(baseUrl)
         .addConverterFactory(ScalarsConverterFactory.create())
         //可以接收自定義的Gson灸叼，當(dāng)然也可以不傳
         .addConverterFactory(GsonConverterFactory.create(gson))
         // 針對(duì)rxjava2.x
         .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
         .client(builder.build())
         .build();

第三步 調(diào)用

NewsService newsService = createRetrofit().create(NewsService.class);
News news = new News();
news.likes = "likes";
news.date = "20170619";
news.title = "Converter用法3";
news.id = 1;
news.views = "views";
Observable<String> observable =  newsService.testInterceptor(news);
observable.subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Observer<String>() {
    @Override
    public void onSubscribe(Disposable d) {
    }
    @Override
    public void onNext(String value) {
        Log("Scalar用法 onNext value:" + value);
    }
    @Override
    public void onError(Throwable e) {
        Log("Scalar用法 onError " + e.getMessage());
        e.printStackTrace();
    }
    @Override
    public void onComplete() {
    }
});

這樣就完成了加密解密了，外面調(diào)用不用關(guān)心里面的加密解密邏輯庆捺，只需要按照以前的邏輯開發(fā)就可以了古今。