首先添加依賴

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'//請求結果直接轉化為實體類，省略gson轉化

創(chuàng)建一個接口

// 完整地址: http://www.wuhaojun.com/api/android/customer?type=1
public interface CustomerService {
    @GET("/api/android/customer")//Get請求地址
    Call<Customer> getCustomer(@Query("type") int type);//定義參數(shù)type的當前是第幾頁 1,2,3 ...
}

請求方法

        String baseUrl = "http://www.wuhaojun.com/";//請求地址，固定的一部分
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(baseUrl)
                .addConverterFactory(GsonConverterFactory.create())//請求結果直接轉化實體類
                .build();

        CustomerService movieService = retrofit.create(CustomerService.class);//創(chuàng)建對象
        Call<Customer> call = movieService.getCustomer(1);//傳遞請求參數(shù) 對應接口中的定義
        call.enqueue(new Callback<Customer>() {
            @Override
            public void onResponse(Call<Customer> call, Response<Customer> response) {
                Log.i(TAG, "onResponse: "+response.body().getMessage());//返回的就是實體類，不需要Gson轉換
            }

            @Override
            public void onFailure(Call<Customer> call, Throwable t) {
                Log.i(TAG, "onFailure: "+t.getMessage());
            }
        });

最后，別忘了添加網(wǎng)絡權限

<uses-permission android:name="android.permission.INTERNET" />

附加其他上傳類型

//post json
    @POST
    Call<String> reJson(@Url String url, @Body RequestBody body);

    HashMap<String, String> params = new HashMap<>();
    params.put("phone_num", "123");
    JSONObject json = new JSONObject(params);
    RequestBody body = RequestBody.create(okhttp3.MediaType.parse("application/json;charset=utf-8"), json);//轉化類型


//post params
    @POST
    @FormUrlEncoded
    Call<String> reParams(@Url String url, @FieldMap Map<String, String> map);

    HashMap<String, String> hashMap = new HashMap<>();
    hashMap.put("user", "test");    
    
    
//post file map
    @POST
    @Multipart
    Call<String> reUploadFile(@Url String url, @PartMap Map<String, RequestBody> params);
    
    File file = new File("");
    Map<String, RequestBody> hashMap = new HashMap<>();
    hashMap.put("json", RequestBody.create(MediaType.parse("text/plain"), "jsonargs"));//鍵值對
    hashMap.put("file\"; filename=\"" + file.getName(), RequestBody.create(MediaType.parse("multipart/form-data"), file));//文件

大神tough1985文章：http://gank.io/post/56e80c2c677659311bed9841