撸代码之前，先简单了解一下为什么Retrofit这么受大家青睐吧。???

Retrofit是Square公司出品的基于OkHttp封装的一套RESTful（目前流行的一套api设计的风格）网络请求框架。它内部使用了大量的设计模式，以达到高度解耦的目的；它可以直接通过注解的方式配置请求；可以使用不同的Http客户端；还可以使用json Converter序列化数据，直接转换成你期望生成的实体bean；它还支持Rxjava等等等（此处省略一万字.....）

好了，接下来开始我们就开始上代码，写个小Demo测试一下它的使用吧！
使用步骤：
1、app的build文件中加入：

//only Retrofit（只用Retrofit联网）compile 'com.squareup.retrofit2:retrofit:2.1.0'compile 'com.squareup.retrofit2:converter-gson:2.1.0'
//Rxjava and Retrofit（Retrofit+Rx需要添加的依赖）compile 'com.squareup.retrofit2:adapter-rxjava:2.1.0'compile 'io.reactivex:rxandroid:1.2.1'compile 'io.reactivex:rxjava:1.2.1'

2、接下来就要编写实现retrofit联网的代码了，以Get请求为例，示例接口：（http://wthrcdn.etouch.cn/weather_mini?city=北京）
首先，你需要创建一个interface用来配置网络请求。
写法《一》：单纯使用Retrofit，不加Rxjava的使用

/**
* 描述：第一步:定义一个接口配置网络请求
*/
public interface WeatherService {
//  网络接口的使用为查询天气的接口
//  @GET("weather_mini")
//  此处回调返回的可为任意类型Call<T>，再也不用自己去解析json数据啦！！！Call<WeatherEntity> getMessage(@Query("city") String city);

在需要请求网络的地方直接调用下面的方法即可：

  /*** 单纯使用Retrofit的联网请求*/private void doRequestByRetrofit() {Retrofit retrofit = new Retrofit.Builder().baseUrl(API.BASE_URL)//基础URL 建议以 / 结尾.addConverterFactory(GsonConverterFactory.create())//设置 Json 转换器.build();WeatherService weatherService = retrofit.create(WeatherService .class);Call<WeatherEntity> call = weatherService.getMessage("北京");call.enqueue(new Callback<WeatherEntity>() {@Overridepublic void onResponse(Call<WeatherEntity> call, Response<WeatherEntity> response) {//测试数据返回WeatherEntity weatherEntity = response.body();Log.e("TAG", "response == " +  weatherEntity.getData().getGanmao());}@Overridepublic void onFailure(Call<WeatherEntity> call, Throwable t) {Log.e("TAG", "Throwable : " + t);}});}

写法《二》 Retrofit + Rxjava
区别：使用Rxjava后，返回的不是Call<T>而是一个Observable<T>的对象了。

public interface RxWeatherService {@GET("weather_mini")Observable<WeatherEntity> getMessage(@Query("city") String city);
}

请求联网代码：

 private void doRequestByRxRetrofit() {Retrofit retrofit = new Retrofit.Builder().baseUrl(API.BASE_URL)//基础URL 建议以 / 结尾.addConverterFactory(GsonConverterFactory.create())//设置 Json 转换器.addCallAdapterFactory(RxJavaCallAdapterFactory.create())//RxJava 适配器.build();RxWeatherService rxjavaService = retrofit.create(RxWeatherService .class);rxjavaService .getMessage("北京").subscribeOn(Schedulers.io())//IO线程加载数据.observeOn(AndroidSchedulers.mainThread())//主线程显示数据.subscribe(new Subscriber<WeatherEntity>() {@Overridepublic void onCompleted() {}@Overridepublic void onError(Throwable e) {}@Overridepublic void onNext(WeatherEntity weatherEntity) {Log.e("TAG", "response == " + weatherEntity.getData().getGanmao());}});}

免费赠送一个WeatherEntity实体类（只给偷懒的小伙伴）：
（在浏览器打开http://wthrcdn.etouch.cn/weather_mini?city=北京，取到json串直接用GsonFormat生成即可）

public class WeatherEntity {private DataBean data;private int status;private String desc;public DataBean getData() {return data;}public void setData(DataBean data) {this.data = data;}public int getStatus() {return status;}public void setStatus(int status) {this.status = status;}public String getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}public static class DataBean {private YesterdayBean yesterday;private String city;private String aqi;private String ganmao;private String wendu;private List<ForecastBean> forecast;public YesterdayBean getYesterday() {return yesterday;}public void setYesterday(YesterdayBean yesterday) {this.yesterday = yesterday;}public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getAqi() {return aqi;}public void setAqi(String aqi) {this.aqi = aqi;}public String getGanmao() {return ganmao;}public void setGanmao(String ganmao) {this.ganmao = ganmao;}public String getWendu() {return wendu;}public void setWendu(String wendu) {this.wendu = wendu;}public List<ForecastBean> getForecast() {return forecast;}public void setForecast(List<ForecastBean> forecast) {this.forecast = forecast;}public static class YesterdayBean {private String date;private String high;private String fx;private String low;private String fl;private String type;public String getDate() {return date;}public void setDate(String date) {this.date = date;}public String getHigh() {return high;}public void setHigh(String high) {this.high = high;}public String getFx() {return fx;}public void setFx(String fx) {this.fx = fx;}public String getLow() {return low;}public void setLow(String low) {this.low = low;}public String getFl() {return fl;}public void setFl(String fl) {this.fl = fl;}public String getType() {return type;}public void setType(String type) {this.type = type;}}public static class ForecastBean {private String date;private String high;private String fengli;private String low;private String fengxiang;private String type;public String getDate() {return date;}public void setDate(String date) {this.date = date;}public String getHigh() {return high;}public void setHigh(String high) {this.high = high;}public String getFengli() {return fengli;}public void setFengli(String fengli) {this.fengli = fengli;}public String getLow() {return low;}public void setLow(String low) {this.low = low;}public String getFengxiang() {return fengxiang;}public void setFengxiang(String fengxiang) {this.fengxiang = fengxiang;}public String getType() {return type;}public void setType(String type) {this.type = type;}}}
}

好了，简单的Retrofit+Rxjava实现联网到此就完成了。本文主要针对初接触retrofit的开发童鞋，如果对你有所帮助，不要忘了点个赞哦！
后续会更新Retrofit+Rxjava在实际项目开发中的运用，可以直接拿来在项目中使用噢.......敬请期待