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写在前面: Retrofit与okhttp共同出自于Square公司，是目前市场上使用最多的联网框架,retrofit是对okhttp做了一层封装,不过封装之后的retrofit上手还是极其复杂,为了解决使用难度问题,本文推荐使用github开源项目RetrofitUtils.

RetrofitUtils开源项目地址：https://github.com/open-android/RetrofitUtils
定义我们请求的Api，我们假设是这样的:
http://www.oschina.net/action/apiv2/banner?catalog=1
返回服务器的数据

{  
"code": 1,  
"message": "success",  
"result": {  
"items": [  
    {  
        "detail": "",  
        "href": "http://www.oschina.net/news/79650/2017-top-programming-languages",  
        "id": 79650,  
        "img": "https://static.oschina.net/uploads/cooperation/75410/google-beta-natural-language-api_048424e4-a8c3-41e8-91ef-aa009e3fc559.jpg",  
        "name": "2017 年热门编程语言排行榜",  
        "pubDate": "2016-12-06 11:51:24",  
        "type": 6  
        },  
    {  
        "detail": "",  
        "href": "https://www.oschina.net/question/2720166_2210842",  
        "id": 2210842,  
        "img": "https://static.oschina.net/uploads/cooperation/75323/ubuntu-forum-black-sql_eb9137ea-efb2-49aa-99fd-025a221dcfe7.jpg",  
        "name": "高手问答 | MySQL 开发和运维规范",  
        "pubDate": "2016-12-06 15:48:10",  
        "type": 2  
    },  
    {  
        "detail": "",  
        "href": "http://www.oschina.net/news/79757/tiobe-12",  
        "id": 79757,  
        "img": "https://static.oschina.net/uploads/cooperation/78083/chrome55-save-at-least-35-percent-memory_70ceba24-eb96-4710-99ec-c1cb5a26a3d6.jpg",  
        "name": "C 语言为何一蹶不振？",  
        "pubDate": "2016-12-08 15:18:20",  
        "type": 6  
    },  
    {  
        "detail": "",  
        "href": "https://www.oschina.net/news/79732/firebug-stop-develope-and-maintain",  
        "id": 79732,  
        "img": "https://static.oschina.net/uploads/cooperation/77929/top-income-programming-languages-2016_16e9be1b-2a6b-453f-bafa-442fd043024b.jpg",  
        "name": "Firebug 宣布不再维护，讲不出再见！",  
        "pubDate": "2016-12-08 10:56:47",  
        "type": 6  
    },  
    {  
        "detail": "",  
        "href": "http://www.oschina.net/news/79673/the-founder-of-cm-was-fired",  
        "id": 79673,  
        "img": "https://static.oschina.net/uploads/cooperation/78455/intellij-idea-2016-3-public-preview_63725513-45e4-4fb2-a0bf-c7940a7a87bc.jpg",  
        "name": "Cyanogen 之父被踢出局",  
        "pubDate": "2016-12-06 11:48:43",  
        "type": 6  
    }],  
    "nextPageToken": "61AF0C190D6BD629",  
    "prevPageToken": "3EA621243546C8A5",  
    "requestCount": 5,  
    "responseCount": 5,  
    "totalResults": 5  
},  
  "time": "2016-12-13 10:56:41"}

这样一个接口我看看使用RetrofitUtils该如何使用

大家看简单实用只需要new一个request然后发送一个send请求,就能返回服务器的数据,并且压根不需要解析拿到的直接就是各位需要的bean对象.那么我们来看看RetrofitUtils的使用步骤

在project的build.gradle添加如下代码(如下图)

引入当前项目

compile 'com.github.open-android:RetrofitUtils:0.1.9'

在清单文件添加如下权限

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

新建Application类并且在oncreate方法当中进行初始化：千万注意Application记得在manifest.xml中注册。

  ItheimaHttp.init(this, Urls.getBaseUrl());

eg:请求地址:http://www.oschina.net/action/apiv2/banner?catalog=1

那么baseUrl = http://www.oschina.net RetrofitUtils内部封装了如下使用方法

看一个完整Get和Post请求是如何实现：异步请求（内部使用Gson解析json数据）直接返回实体bean对象

Request request = ItheimaHttp.newGetRequest(apiUrl);//apiUrl格式："xxx/xxxxx"  
Call call = ItheimaHttp.send(request, new HttpResponseListener<Bean>() {  
    @Override  
    public void onResponse(Bean bean) {  
    ........  
    }  
     /** 
     * 可以不重写失败回调 
     * @param call 
     * @param e 
     */  
    @Override  
    public void onFailure(Call<ResponseBody> call, Throwable e) {  
    ......  
    }  
});  
@param httpResponseListener 回调监听  
@param <T> Bean  
@return Call可以取消网络请求</span>

添加请求参数

request.putParams(key,value)  
.putParams(key,value)  
.putParams(key,value);  


Map<String,Object> map = new HashMap<>();  
map.put(key,value);  
request.putParamsMap(map);

添加请求头

request.putHeader(key,value)  
.putHeader(key,value);

如果不需要RetrofitUtils框架自动解析json,那么可以使用如下请求

Call call = ItheimaHttp.getAsync(apiUrl, new HttpResponseListener<String>);  

Call call = ItheimaHttp.postAsync(apiUrl, new HttpResponseListener<String>() {  
    @Override  
    public void onResponse(String s) {  
    ........  
    }  
});

如果需要RetrofitUtils框架自动解析json,直接获取javabean,那么可以使用如下请求

Call call = ItheimaHttp.getAsync(apiUrl, new HttpResponseListener<Bean>);  

Call call = ItheimaHttp.postAsync(apiUrl, new HttpResponseListener<Bean>() {  
    @Override  
    public void onResponse(Bean bean) {  
    ........  
    }  
});

文件上传

Request request = ItheimaHttp.newUploadRequest("http://xxx/xxx/xxx", RequestMethod.POST);  
request.putUploadFile(uploadFile).putMediaType(MediaType.parse("multipart/form-data"));  
ItheimaHttp.upload(request, new UploadListener() {  
    @Override  
    public void onResponse(Call call, Response response) {  
    //上传成功回调  
    }  
    
    @Override  
    public void onProgress(long progress, long total, boolean done) {  
    //上传进度回调progress:上传进度，total:文件长度， done:上传是否完成  
    }  
    
    @Override  
    public void onFailure(Call call, Throwable t) {  
    //上传失败  
    }  
});

取消网络请求

call.cancel();