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

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