什么是 Retrofit ?
Retrofit是Square开发的一个Android和Java的REST客户端库。这个库非常简单并且具有很多特性，相比其他的网络库，更容易让初学者快速掌握。它可以处理GET、POST、PUT、DELETE…等请求，还可以使用picasso加载图片。
一、再次膜拜下Retrofit
Retrofit无论从性能还是使用方便性上都很屌！！！，本文不去介绍其运作原理（虽然很想搞明白），后面会出专题文章解析Retrofit的内部原理；本文只是从使用上解析Retrofit实现多图片/文件、图文上传的功能。
二、概念介绍
1）注解@Multipart
从字面上理解就是与多媒体文件相关的，没错，图片、文件等的上传都要用到该注解，其中每个部分需要使用@Part来注解。。看其注释
/** * Denotes that the request body is multi-part. Parts should be declared as parameters and * annotated with {@link Part @Part}. */
2）注解@PartMap
当然可以理解为使用@PartMap注释，传递多个Part，以实现多文件上传。注释
/** * Denotes name and value parts of a multi-part request. * <p> * Values of the map on which this annotation exists will be processed in one of two ways: * <ul> * <li>If the type is {@link okhttp3.RequestBody RequestBody} the value will be used * directly with its content type.</li> * <li>Other object types will be converted to an appropriate representation by using * {@linkplain Converter a converter}.</li> * </ul> * <p> * <pre><code> * @Multipart * @POST("/upload") * Call<ResponseBody> upload( * @Part("file") RequestBody file, * @PartMap Map<String, RequestBody> params); * </code></pre> * <p> * A {@code null} value for the map, as a key, or as a value is not allowed. * * @see Multipart * @see Part */
3）RequestBody
从上面注释中就可以看到参数类型是RequestBody，其就是请求体。文件上传就需要参数为RequestBody。官方使用说明如下http://square.github.io/retrofit/
Multipart parts use one of Retrofit's converters or they can implement RequestBody to handle their own serialization.
四、基本实现
了解了以上概念，下面就一一实现
1）接口定义
public interface IHttpService { @Multipart @POST("nocheck/file/agree.do") Call<BaseBean> upLoadAgree(@PartMap Map<String, RequestBody>params); }
BaseBean是根据服务端返回数据进行定义的，这个使用时可以根据自有Server定义。
2）Retrofit实现
/** * Created by DELL on 2017/3/16. * 上传文件用（包含图片） */ public class RetrofitHttpUpLoad { /** * 超时时间60s */ private static final long DEFAULT_TIMEOUT = 60; private volatile static RetrofitHttpUpLoad mInstance; public Retrofit mRetrofit; public IHttpService mHttpService; private Map<String, RequestBody> params = new HashMap<String, RequestBody>(); private RetrofitHttpUpLoad() { mRetrofit = new Retrofit.Builder() .baseUrl(UrlConfig.ROOT_URL) .client(genericClient()) .addConverterFactory(GsonConverterFactory.create()) .build(); mHttpService = mRetrofit.create(IHttpService.class); } public static RetrofitHttpUpLoad getInstance() { if (mInstance == null) { synchronized (RetrofitHttpUpLoad.class) { if (mInstance == null) mInstance = new RetrofitHttpUpLoad(); } } return mInstance; } /** * 添加统一超时时间,http日志打印 * * @return */ public static OkHttpClient genericClient() { HttpLoggingInterceptor logging = new HttpLoggingInterceptor(); logging.setLevel(HttpLoggingInterceptor.Level.BODY); OkHttpClient httpClient = new OkHttpClient.Builder() .addInterceptor(logging) .connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS) .writeTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS) .readTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS) .build(); return httpClient; } /** * 将call加入队列并实现回调 * * @param call 调入的call * @param retrofitCallBack 回调 * @param method 调用方法标志，回调用 * @param <T> 泛型参数 */ public static <T> void addToEnqueue(Call<T> call, final RetrofitCallBack retrofitCallBack, final int method) { final Context context = MyApplication.getContext(); call.enqueue(new Callback<T>() { @Override public void onResponse(Call<T> call, Response<T> response) { LogUtil.d("retrofit back code ====" + response.code()); if (null != response.body()) { if (response.code() == 200) { LogUtil.d("retrofit back body ====" + new Gson().toJson(response.body())); retrofitCallBack.onResponse(response, method); } else { LogUtil.d("toEnqueue, onResponse Fail:" + response.code()); ToastUtil.makeShortText(context, "网络连接错误" + response.code()); retrofitCallBack.onFailure(response, method); } } else { LogUtil.d("toEnqueue, onResponse Fail m:" + response.message()); ToastUtil.makeShortText(context, "网络连接错误" + response.message()); retrofitCallBack.onFailure(response, method); } } @Override public void onFailure(Call<T> call, Throwable t) { LogUtil.d("toEnqueue, onResponse Fail unKnown:" + t.getMessage()); t.printStackTrace(); ToastUtil.makeShortText(context, "网络连接错误" + t.getMessage()); retrofitCallBack.onFailure(null, method); } }); } /** * 添加参数 * 根据传进来的Object对象来判断是String还是File类型的参数 */ public RetrofitHttpUpLoad addParameter(String key, Object o) { if (o instanceof String) { RequestBody body = RequestBody.create(MediaType.parse("text/plain;charset=UTF-8"), (String) o); params.put(key, body); } else if (o instanceof File) { RequestBody body = RequestBody.create(MediaType.parse("multipart/form-data;charset=UTF-8"), (File) o); params.put(key + "\"; filename=\"" + ((File) o).getName() + "", body); } return this; } /** * 构建RequestBody */ public Map<String, RequestBody> bulider() { return params; } }
其中定义了Retrofit实例、还用拦截器定义了统一的超时时间和日志打印；将call加入队列并实现回调。最重要的就是添加参数：
/** * 添加参数 * 根据传进来的Object对象来判断是String还是File类型的参数 */ public RetrofitHttpUpLoad addParameter(String key, Object o) { if (o instanceof String) { RequestBody body = RequestBody.create(MediaType.parse("text/plain;charset=UTF-8"), (String) o); params.put(key, body); } else if (o instanceof File) { RequestBody body = RequestBody.create(MediaType.parse("multipart/form-data;charset=UTF-8"), (File) o); params.put(key + "\"; filename=\"" + ((File) o).getName() + "", body); } return this; }
这里就是根据传入的参数，返回不同的RequestBody。
3）使用
private void upLoadAgree() { showWaitDialog(); RetrofitHttpUpLoad retrofitHttpUpLoad = RetrofitHttpUpLoad.getInstance(); if (!StringUtil.isEmpty(pathImage[0])){ retrofitHttpUpLoad = retrofitHttpUpLoad.addParameter("pic1",new File(pathImage[0])); } if (!StringUtil.isEmpty(pathImage[1])){ retrofitHttpUpLoad = retrofitHttpUpLoad.addParameter("pic2", new File(pathImage[1])); } if (!StringUtil.isEmpty(pathImage[2])){ retrofitHttpUpLoad = retrofitHttpUpLoad.addParameter("zip", new File(pathImage[2])); } Map<String, RequestBody> params = retrofitHttpUpLoad .addParameter("status", "4") .addParameter("pickupId", tv_orderquality_pid.getText().toString()) .addParameter("cause", reason) .addParameter("connectname", et_orderquality_lxrname.getText().toString()) .addParameter("connectphone", et_orderquality_lxrphone.getText().toString()) .addParameter("details", et_orderquality_xqms.getText().toString()) .bulider(); RetrofitHttpUpLoad.addToEnqueue(RetrofitHttpUpLoad.getInstance().mHttpService.upLoadAgree(params), this, HttpStaticApi.HTTP_UPLOADAGREE); }
需要注意的是要对图片及文件路径进行判空操作，负责会报异常W/System.err: java.io.FileNotFoundException: /: open failed: EISDIR (Is a directory)
以上所述是小编给大家介绍的Android基于Retrofit实现多图片/文件、图文上传功能，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！