# Android retrofit的简单封装

**Published by:** [xiaoming.eth](https://paragraph.com/@xiaoming/)
**Published on:** 2022-01-09
**URL:** https://paragraph.com/@xiaoming/android-retrofit

## Content

1.Retrofit是基于OkHttp网络请求框架的二次封装而已，懂Okhttp的小伙伴，那么Retrofit也就基本都会。 2.Retrofit采用注解配置请求的方式： 3.性能最好，处理最快 4.使用REST API时非常方便； 5.传输层默认就使用OkHttp； 6.支持NIO； 7.拥有出色的API文档和社区支持 8.速度上比volley更快； 9.如果你的应用程序中集成了OKHttp，Retrofit默认会使用OKHttp处理其他网络层请求。 10.默认使用Gson一：retrofit的使用Retrofit支持同步和异步两种方式，在使用时，需要将请求地址转换为接口，通过注解来指定请求方法，请求参数，请求头，返回值等信息。get请求到服务器后从数据库查询数据，返回值为查询到的数据，post请求向服务器提交一条数据，返回值为提交的数据。一：首先完成请求所用的service，是一个interface，完全通过注解完成配置。 倚赖需要的包 compile 'com.squareup.retrofit2:retrofit:2.1.0' compile 'com.google.code.gson:gson:2.8.0' public interface DouBanApiClient { /** *@param headers 请求参数头 *@param url 请求的地址 *@param params 请求的参数 */ @GET() Call<ResponseBody> get(@HeaderMap Map<String, String> headers, @Url String url, @QueryMap Map<String, String> params); @FormUrlEncoded @POST() Call<String> post(@HeaderMap Map<String, String> headers, @Url String url, @FieldMap Map<String, String> params); @Streaming @GET() Call<ResponseBody> download(@HeaderMap Map<String, String> headers, @Url String url, @QueryMap Map<String, String> params); } 二：创建一个请求单例 ApiClient，方便管理网络请求，本文只给出get请求的实现方式。 （ApiBuilder 构建的参数 包含 请求 url header params，后文会贴出代码）/** * * 网络请求类 * Created by Administrator on 2017/2/13 0013. */ public class ApiClient { static ApiClient instance; public final static String BASE_API = "http://app.youxiake.com"; /** * 请求的接口 * */ public static String Api_BookInfo = "/api/discover/list/hot"; /*** * * 构建 retrofit请求 * */ private final static Retrofit retrofit = new Retrofit.Builder() .baseUrl(ApiClient.BASE_API) .build(); /** * 获得 DouBanApiClient实例 * @return */ public DouBanApiClient getDbService(){ return retrofit.create(DouBanApiClient.class); } /** * 创建请求单例 * @return */ public static ApiClient getInstance(){ if(instance == null){ synchronized (ApiClient.class){ if(instance ==null){ instance = new ApiClient(); } } } return instance; } /** * * get请求 * @param builder request构建的参数 包含 url header params * @param onCallback rquest 回调 * @param classOf 指定请求的model类型 * @param <T> */ public <T> void doGet(ApiBuilder builder ,final com.retrofitdemo.interfaces.CallBack<T> onCallback,final Class classOf){ DouBanApiClient dbService = getDbService(); Call<ResponseBody> stringCall = dbService.get(checkHeaders(builder.headers), checkUrl(builder.url), checkParams(builder.params)); stringCall.enqueue(new Callback<ResponseBody>() { @Override public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) { Object o = null; try { Log.d("TAG","----"+response.body().string()); o = new Gson().fromJson(response.body().string(), classOf); } catch (IOException e) { e.printStackTrace(); } onCallback.onSuccess(call, (T) o); } @Override public void onFailure(Call<ResponseBody> call, Throwable t) { onCallback.onFailure(call,t); Log.d("TAG","----"+t.getMessage()); } }); } private String checkUrl(String url) { if (checkNULL(url)) { return null; } return url; } // 判断是否NULL public static boolean checkNULL(String str) { return str == null || "null".equals(str) || "".equals(str); } // 判断是否NULL public static void Error(Context context, String msg) { if (checkNULL(msg)) { msg = "未知异常"; } Toast.makeText(context, msg, Toast.LENGTH_SHORT).show(); } public static Map<String, String> checkHeaders(Map<String, String> headers) { if (headers == null) { headers = new HashMap<>(); } //retrofit的headers的值不能为null，此处做下校验，防止出错 for (Map.Entry<String, String> entry : headers.entrySet()) { if (entry.getValue() == null) { headers.put(entry.getKey(), ""); } } return headers; } public static Map<String, String> checkParams(Map<String, String> params) { if (params == null) { params = new HashMap<>(); } //retrofit的params的值不能为null，此处做下校验，防止出错 for (Map.Entry<String, String> entry : params.entrySet()) { if (entry.getValue() == null) { params.put(entry.getKey(), ""); } } return params; } } 三：构建请求的参数 /** * Created by cvmars 2017/2/14 0014. */ public class ApiBuilder { Map<String, String> params ; Map<String, String> headers ; String url; public ApiBuilder Params(Map<String, String> params) { this.params.putAll(params); return this; } public ApiBuilder Params(String key, String value) { this.params.put(key, value); return this; } public ApiBuilder Headers(Map<String, String> headers) { this.headers.putAll(headers); return this; } public ApiBuilder Headers(String key, String value) { this.headers.put(key, value); return this; } public ApiBuilder Url(String url) { this.url = url; return this; } public ApiBuilder(String url) { this.setParams(url); } public ApiBuilder() { this.setParams(null); } private void setParams(String url) { this.url = url; this.params = new HashMap<>(); this.headers = new HashMap<>(); } } 四：回调接口 public interface CallBack<T> { void onSuccess(Call<ResponseBody> call, T response); void onFailure(Call<ResponseBody> call, Throwable t); } 五：简单的封装基本完成：下面是基本使用方法 先创建返回的modelpublic class FindContent { public String msg; public int code; public DataBean data; public static class DataBean { public int total; public int totalPage; public int pageSize; public List<QuotesListBean> quotesList; public static class QuotesListBean { public String content; public String uid; public String address; public String show_address; public String comment; public String prise; public String gmt_create; public String type; public String video; public Object activity; public String username; public String avatar; public int quote_id; public String relation; public String share_url; public boolean prised; public List<ImagesBean> images; public List<?> discus; public static class ImagesBean { public String width; public String height; public String url; public String url_xl; public String url_l; public String url_m; public List<?> labels_info; } } } } 在需要请求的地方进行调用 ApiBuilder builder = new ApiBuilder(ApiClient.Api_BookInfo) .Headers("header1","this is request header") .Headers("header2","this is request header2") .Params("params","this is request params"); ApiClient.getInstance().doGet(builder, new CallBack<FindContent>() { @Override public void onSuccess(Call<ResponseBody> call, FindContent response) { mContent.setText(response.toString()); } @Override public void onFailure(Call<ResponseBody> call, Throwable t) { } },FindContent.class); }

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