Android 进阶之第三方库的介绍 Retrofit

简单应用实例：

在介绍如何使用Retrofit之前先做点准备。首先要有个开放的API供我们使用网络去获取信息，接下来的例子将使用OpenWeather来练习下，如下是openWeather的地址：
http://openweathermap.org/
和众多的API一样都需要申请一个开发者的key，申请key的过程就不在这里介绍了。

在AS中引入RxJava + Retrofix

apply plugin: 'com.android.application'
android {
    compileSdkVersion 23
    buildToolsVersion "23.0.3"

    defaultConfig {
        applicationId "com.idealist.doumusic"
        minSdkVersion 15
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.3.0'
    compile 'com.android.support:design:23.3.0'
    
    compile 'io.reactivex:rxjava:1.1.0'
    compile 'io.reactivex:rxandroid:1.1.0'
    compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0-beta4'
    compile 'com.squareup.retrofit2:retrofit:2.0.0-beta4'
    compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta4'
    compile 'com.google.code.gson:gson:2.6.2'
}

开始我们先创建一个接口,关键部分先留空，后面我带大家一点一点往上面填：

public interface IDouMusic {
    @GET("")
    Callback<WheatherResult> getWheatherResult();

}

首先到这一步大家一定都申请了对应的APPID，也就是对应的APIkey，类似f8d8ead8299f963abcded5c40c0bcb81
找不到申请地方的我这里贴个地址：http://openweathermap.org/appid
申请到APPID后怎么使用呢？整个模板是这样的，只要在最后的申请后面添加APIKEY即可
http://api.openweathermap.org/data/2.5/forecast/city?id=524901&APPID={APIKEY}
前面的又是什么呢？大家进入这个页面http://openweathermap.org/api 这里面有很多的查询方案，作为例子我们选个简单的，当前的天气情况：
http://openweathermap.org/current 这里提供了很多的查询方式，可以按照城市名，城市id等信息查询。
你不知道城市id怎么表示？可以到这个地方下载city.list.json 查询 http://bulk.openweathermap.org/sample/
比如我们以广东惠州为例，查询当天天气，那么访问的地址应该是：http://api.openweathermap.org/data/2.5/weather?q=Huizhou&APPID=f8d8ead8299f963abcded5c40c0bcb81
注意这里的APIKey需要换成大家自己申请的。将上述的地址拷贝到浏览器上这时候就会返回下面信息：

{
    "coord": {
        "lon": 114.4,
        "lat": 23.08
    },
    "weather": [
        {
            "id": 802,
            "main": "Clouds",
            "description": "scattered clouds",
            "icon": "03n"
        }
    ],
    "base": "stations",
    "main": {
        "temp": 300.93,
        "pressure": 995,
        "humidity": 49,
        "temp_min": 300.93,
        "temp_max": 300.93
    },
    "wind": {
        "speed": 1.03,
        "gust": 7.71
    },
    "rain": {},
    "clouds": {
        "all": 48
    },
    "dt": 1463923088,
    "sys": {
        "type": 3,
        "id": 187827,
        "message": 0.0145,
        "country": "CN",
        "sunrise": 1463866709,
        "sunset": 1463914799
    },
    "id": 1806776,
    "name": "Huizhou",
    "cod": 200
}

OK，到这一步我们来实现这个功能：
由于要访问到网络所以需要添加网络访问权限：

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

紧接着完善刚刚提到的那个接口：
为什么是@GET(“weather”)？我们上面提到要访问的地址为：

http://api.openweathermap.org/data/2.5/weather?q=Huizhou&APPID=f8d8ead8299f963abcded5c40c0bcb81

去除掉访问参数后的地址为：

http://api.openweathermap.org/data/2.5/weather

我们再看OpenWeather的API，其中http://api.openweathermap.org/data/2.5/ 为公共部分，最后一个是变化的，我们将http://api.openweathermap.org/data/2.5/ 作为baseUri
weather作为地址的区别部分。这里需要注意的是baseuri一定要以’/‘结尾，GET(“weather”)这个不能以/开头，刚开始使用的时候由于这个原因导致了获取不到返回值，具体为什么，我将会在介绍完这个例子后给大家介绍下。

public interface IDouWheather {
    @GET("weather")
    Call<WheatherResult> getWheatherResult(@Query("q") String cityName, @Query("APPID") String ApiId);
}

关于访问接口还有如下的写法,这里介绍的是Path的用法。

public interface GitHub {
    @GET("/repos/{owner}/{repo}/contributors")
    Call<List<Contributor>> contributors(@Path("owner") String owner,@Path("repo") String repo);
}

//baseurl 定义
String baseUrl = "http://api.openweathermap.org/data/2.5/";

//创建Retrofit：
Retrofit retrofit = new Retrofit.Builder()
        /**
        使用Retrofit会将Json数据直接解析转换成java 对象，因此需要用到json 解析库作为转换器
        这里使用GSON解析数据，但是retrofit2还支持如下列表的解析器：

    Gson: com.squareup.retrofit2:converter-gson 
    Jackson: com.squareup.retrofit2:converter-jackson 
    Moshi： com.squareup.retrofit2:converter-moshi 
    Protobuf: com.squareup.retrofit2:converter-protobuf 
    Wire: com.squareup.retrofit2:converter-wire 
    Simple XML:com.squareup.retrofit2:converter-simplexml
            */
        .addConverterFactory(GsonConverterFactory.create())
        .baseUrl(baseUrl)
        /*需要注意下BASE_URL这个参数，如果@GET方法里的URl是完整的，则不拼接参数，否则拼接URL*/
        .build();
 //创建访问服务：
IDouWheather weatherService = retrofit.create(IDouWheather.class);
//将参数传递进去：
Call<WheatherResult> call = weatherService.getWheatherResult("Huizhou", "f8d8ead8299f963abcded5c40c0bcb89");
//异步访问：
call.enqueue(new Callback<WheatherResult>() {
    //回调函数发生在主线程，可以进行UI相关的操作
    @Override
    public void onResponse(Call<WheatherResult> call, Response<WheatherResult> response) {
        if(response.isSuccess()) {
            //获取返回结果
            WheatherResult result = response.body();
            Log.i("xiaohai.lin", "getName = " + result.getName());
            Log.i("xiaohai.lin", "getTemp = " + result.getMain().getTemp());
            Log.i("xiaohai.lin", "getLat = " + result.getCoord().getLat());
            Log.i("xiaohai.lin", "getLon = " + result.getCoord().getLon());
            Log.i("xiaohai.lin", "getDescription = " + result.getWeather().get(0).getDescription());
        }
    }
    @Override
    public void onFailure(Call<WheatherResult> call, Throwable t) {

    }
});

下面是返回数据对应的Bean，这个我是使用GSONFormat插件自动生成的：注意这里可以不用实现全部的节点，但是一定要注意，参数名一定要和返回的json数据的key一致：

public class WheatherResult {
    /**
     * lon : 114.4
     * lat : 23.08
     */

    private CoordBean coord;
    /**
     * coord : {"lon":114.4,"lat":23.08}
     * weather : [{"id":803,"main":"Clouds","description":"broken clouds","icon":"04n"}]
     * base : stations
     * main : {"temp":302.04,"pressure":994,"humidity":56,"temp_min":302.04,"temp_max":302.04}
     * wind : {"speed":2.49,"deg":144}
     * rain : {}
     * clouds : {"all":68}
     * dt : 1464103691
     * sys : {"type":3,"id":187827,"message":0.0114,"country":"CN","sunrise":1464039473,"sunset":1464087657}
     * id : 1806776
     * name : Huizhou
     * cod : 200
     */

    private String base;
    /**
     * temp : 302.04
     * pressure : 994
     * humidity : 56
     * temp_min : 302.04
     * temp_max : 302.04
     */

    private MainBean main;
    /**
     * speed : 2.49
     * deg : 144
     */

    private WindBean wind;
    private RainBean rain;
    /**
     * all : 68
     */

    private CloudsBean clouds;
    private int dt;
    /**
     * type : 3
     * id : 187827
     * message : 0.0114
     * country : CN
     * sunrise : 1464039473
     * sunset : 1464087657
     */

    private SysBean sys;
    private int id;
    private String name;
    private int cod;
    /**
     * id : 803
     * main : Clouds
     * description : broken clouds
     * icon : 04n
     */

    private List<WeatherBean> weather;

    public CoordBean getCoord() {
        return coord;
    }

    public void setCoord(CoordBean coord) {
        this.coord = coord;
    }

    public String getBase() {
        return base;
    }

    public void setBase(String base) {
        this.base = base;
    }

    public MainBean getMain() {
        return main;
    }

    public void setMain(MainBean main) {
        this.main = main;
    }

    public WindBean getWind() {
        return wind;
    }

    public void setWind(WindBean wind) {
        this.wind = wind;
    }

    public RainBean getRain() {
        return rain;
    }

    public void setRain(RainBean rain) {
        this.rain = rain;
    }

    public CloudsBean getClouds() {
        return clouds;
    }

    public void setClouds(CloudsBean clouds) {
        this.clouds = clouds;
    }

    public int getDt() {
        return dt;
    }

    public void setDt(int dt) {
        this.dt = dt;
    }

    public SysBean getSys() {
        return sys;
    }

    public void setSys(SysBean sys) {
        this.sys = sys;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getCod() {
        return cod;
    }

    public void setCod(int cod) {
        this.cod = cod;
    }

    public List<WeatherBean> getWeather() {
        return weather;
    }

    public void setWeather(List<WeatherBean> weather) {
        this.weather = weather;
    }

    public static class CoordBean {
        private double lon;
        private double lat;

        public double getLon() {
            return lon;
        }

        public void setLon(double lon) {
            this.lon = lon;
        }

        public double getLat() {
            return lat;
        }

        public void setLat(double lat) {
            this.lat = lat;
        }
    }

    public static class MainBean {
        private double temp;
        private int pressure;
        private int humidity;
        private double temp_min;
        private double temp_max;

        public double getTemp() {
            return temp;
        }

        public void setTemp(double temp) {
            this.temp = temp;
        }

        public int getPressure() {
            return pressure;
        }

        public void setPressure(int pressure) {
            this.pressure = pressure;
        }

        public int getHumidity() {
            return humidity;
        }

        public void setHumidity(int humidity) {
            this.humidity = humidity;
        }

        public double getTemp_min() {
            return temp_min;
        }

        public void setTemp_min(double temp_min) {
            this.temp_min = temp_min;
        }

        public double getTemp_max() {
            return temp_max;
        }

        public void setTemp_max(double temp_max) {
            this.temp_max = temp_max;
        }
    }

    public static class WindBean {
        private double speed;
        private int deg;

        public double getSpeed() {
            return speed;
        }

        public void setSpeed(double speed) {
            this.speed = speed;
        }

        public int getDeg() {
            return deg;
        }

        public void setDeg(int deg) {
            this.deg = deg;
        }
    }

    public static class RainBean {
    }

    public static class CloudsBean {
        private int all;

        public int getAll() {
            return all;
        }

        public void setAll(int all) {
            this.all = all;
        }
    }

    public static class SysBean {
        private int type;
        private int id;
        private double message;
        private String country;
        private int sunrise;
        private int sunset;

        public int getType() {
            return type;
        }

        public void setType(int type) {
            this.type = type;
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public double getMessage() {
            return message;
        }

        public void setMessage(double message) {
            this.message = message;
        }

        public String getCountry() {
            return country;
        }

        public void setCountry(String country) {
            this.country = country;
        }

        public int getSunrise() {
            return sunrise;
        }

        public void setSunrise(int sunrise) {
            this.sunrise = sunrise;
        }

        public int getSunset() {
            return sunset;
        }

        public void setSunset(int sunset) {
            this.sunset = sunset;
        }
    }

    public static class WeatherBean {
        private int id;
        private String main;
        private String description;
        private String icon;

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getMain() {
            return main;
        }

        public void setMain(String main) {
            this.main = main;
        }

        public String getDescription() {
            return description;
        }

        public void setDescription(String description) {
            this.description = description;
        }

        public String getIcon() {
            return icon;
        }

        public void setIcon(String icon) {
            this.icon = icon;
        }
    }
}

点击运行就可以直接获取返回的结果了。

基本用法：

Retrofix && RxJava：

使用RXJava会使得整个流程会显得更加清晰，在原先项目中加入RxJava步骤很简单只需要在原有的基础上作如下改动即可：

在build.gradle中加入：

compile 'io.reactivex:rxjava:1.1.0'
compile 'io.reactivex:rxandroid:1.1.0'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0-beta4'

这时候接口就不能是Call了，而应该是Observable：

public interface IDouMusic {
    @GET("weather")
    Observable<WheatherResult> getWheatherResult(@Query("q") String cityName, @Query("APPID") String ApiId);
}

String baseUrl = "http://api.openweathermap.org/data/2.5/";
Retrofit retrofit = new Retrofit.Builder()
        .addConverterFactory(GsonConverterFactory.create())
        //添加RxJavaCallAdapterFactory
        .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
        .baseUrl(baseUrl)
        .build();

IDouMusic weatherService = retrofit.create(IDouMusic.class);
Observable<WheatherResult> observable = weatherService.getWheatherResult("Huizhou", "f8d8ead8299f963abcded5c40c0bcb89");
//在IO线程执行网络查询
observable.subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
//切换到主线程在主线程更新UI
        .subscribe(new Subscriber<WheatherResult>() {
            @Override
            public void onCompleted() {}
            @Override
            public void onError(Throwable e) {}
            @Override
            public void onNext(WheatherResult wheatherResult) {
                Log.i("xiaohai.lin", "getName = " + wheatherResult.getName());
                Log.i("xiaohai.lin", "getTemp = " + wheatherResult.getMain().getTemp());
                Log.i("xiaohai.lin", "getLat = " + wheatherResult.getCoord().getLat());
                Log.i("xiaohai.lin", "getLon = " + wheatherResult.getCoord().getLon());
                Log.i("xiaohai.lin", "getDescription = " + wheatherResult.getWeather().get(0).getDescription());
            }
        });

Retrofix && Realm：

Realm 可以与 Retrofit 1.x 和 2.x 无缝配合工作。但注意 Retrofit 不会自动将对象存入 Realm。
你需要通过调用 Realm.copyToRealm() 或 Realm.copyToRealmOrUpdate() 来将它们存入 Realm。

GitHubService service = restAdapter.create(GitHubService.class);
List<Repo> repos = service.listRepos("octocat");

// Copy elements from Retrofit to Realm to persist them.
realm.beginTransaction();
List<Repo> realmRepos = realm.copyToRealmOrUpdate(repos);
realm.commitTransaction();

Retrofix2 新特性：

http://api.openweathermap.org/data/2.5/weather?q=Huizhou&APPID=f8d8ead8299f963abcded5c40c0bcb89
https://gank.io/post/56e80c2c677659311bed9841
https://yq.aliyun.com/articles/26705

http://www.07net01.com/program/2016/02/1307334.html
http://www.jianshu.com/p/c1a3a881a144
https://twiceyuan.com/2015/12/26/retrofit2-0/?utm_source=tuicool&utm_medium=referral
http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0915/3460.html
http://blog.csdn.net/liuhongwei123888/article/details/50375283
http://www.cnblogs.com/angeldevil/p/3757335.html
http://www.bkjia.com/Androidjc/995850.html
http://blog.csdn.net/lizelinll/article/details/42361327
http://www.tuicool.com/articles/6zIvQbb
http://www.tuicool.com/articles/fQju2uQ
http://blog.csdn.net/tiankong1206/article/details/46486401
http://blog.csdn.net/caroline_wendy/article/details/50557470

http://www.cxbiao.com/2016/05/14/Retrofit2%E4%B8%8ERxJava%E7%94%A8%E6%B3%95%E8%A7%A3%E6%9E%90/
http://www.jcodecraeer.com/plus/view.php?aid=3460