Android Retrofit实现多图片/文件、图文上传功能

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我们网站的支持！