Retrofit 2.0使用

叁歲伎倆 2022-06-12 06:08 168阅读 0赞

# 1.添加依赖 #

app/build.gradle文件中`dependencies`标签下，添加：

compile 'com.squareup.retrofit2:retrofit:2.3.0'

# 2.接口API #

网络接口用的是[和风天气][Link 1]的免费接口

定义接口

public interface ApiService { 
    
        //url实例：https://free-api.heweather.com/v5/weather?city=yourcity&key=yourkey
        //正常的网络请求api,@Query参数会直接显示在url里
        @GET("weather")
        Call<ResponseBody> getWeather(@Query("city") String city, @Query("key") String key);
    
    }

# 3.异步调用接口 #

//自己注册后的key
    private static final String KEY = "124***fasdf****dcf*****3";
    
    //创建Retrofit对象，设置baseUrl，Retrofit2.0的baseurl需要`/`结尾
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://free-api.heweather.com/v5/")
            .build();
    
    //接口调用api，传入查询的参数
    ApiService apiService = retrofit.create(ApiService.class);
    Call<ResponseBody> call = apiService.getWeather("上海", KEY);
    //同步用call.execute();
    call.enqueue(new Callback<ResponseBody>() {
                @Override
                public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
                    try {
                        Log.i("test", "result = \n" + response.body().string());
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                @Override
                public void onFailure(Call<ResponseBody> call, Throwable t) {
                    Log.i("test", "onFailure");
                }
            });
    
    //请求移除用call.cancel();

# 4.@Path和@Query #

2中使用的是`@Query`，直接显示在url的查询条件，还可以通过变量控制url路径的`@Path`

使用@Path

//url中的变量用{}包括，并且与@Paht中声明的值相同
    @GET("{user_name}/article/details/{blog_id}")
    Call<ResponseBody> getBLog(@Path("user_name") String userName, @Path("blog_id") String blogId);

# 5.POST方式提交，用@Body 包装表单数据类 #

首先要添加转化Gson的支持，可直接将@Body 表示的类封装成json数据。添加依赖：

compile 'com.squareup.retrofit2:converter-gson:2.0.2'

接着为`retrofit`添加转换工厂

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://xxxx.xxxx.com/user/")
            //添加Gson转换
            .addConverterFactory(GsonConverterFactory.create())
            .build();

接口api

比如某个登录接口

//注意是POST格式才能用@Body
    @POST("login")
    Call<ResponseBody> loginByBean(@Body LoginUser user);

定义的LoginUser

public class LoginUser { 
    
        //用@SerializedName() 可以指明json转换时候的字段名字
        @SerializedName("name")
        private String user_name;
        @SerializedName("password")
        private String user_password;
        @SerializedName("check")
        private String checkCode;
    
    
        public LoginUser(String user_name, String user_password, String checkCode) {
            this.user_name = user_name;
            this.user_password = user_password;
            this.checkCode = checkCode;
        }
    
        //setter and getter
        ...
    }

异步调用发起请求

//直接传入LoginUser对象
    apiService.loginByBean(new LoginUser("jack", "123123", "asdf"))
            .enqueue(new Callback<ResponseBody>() {
                @Override
                public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
                    try {
                        Log.i("test", "by body ,result = \n" + response.body().string());
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                @Override
                public void onFailure(Call<ResponseBody> call, Throwable t) {
                    Log.i("test", "onFailure");
                }
            });

添加gons转换后，还可以直接将返回的结果类型变为需要的类型。

api接口

//泛型直接指定为Weather
    @GET("weather")
    Call<Weather> getWeatherToWeatherBean(@Query("city") String city, @Query("key") String key);

创建Weather类，可使用`AndroidStudio`插件`GsonFormat`快速将json数据准换成java类。

最后调用

Call<Weather> call = apiService.getWeatherToWeatherBean("上海", KEY);
    call.enqueue(new Callback<Weather>() {
        @Override
        public void onResponse(Call<Weather> call, Response<Weather> response) {
        //可以直接.getHeWeather5()然后调用类成员
            Log.i("test", "to weather bean : " + response.body()
                    .getHeWeather5().get(0).getAqi().toString());
        }
        @Override
        public void onFailure(Call<Weather> call, Throwable t) {
        }
    });

# 6.添加CallAdapter工厂，使用RxJava #

添加依赖：

compile 'io.reactivex.rxjava2:rxjava:2.1.1'
    compile 'io.reactivex.rxjava2:rxandroid:2.0.1'

然后给retrofit添加Rxjava工厂

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://free-api.heweather.com/v5/")
            //gons转换工厂
            .addConverterFactory(GsonConverterFactory.create())
            //rxjava-calladapter工厂
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .build();

API接口更改：

//注意 Call换成了OBservable被观察者
    @GET("weather") Observable<Weather> getWeatherByRxjava(@Query("city") String city, @Query("key") String key);

最后调用

Observable<Weather> call = apiService.getWeatherByRxjava("上海", KEY);
    //异步网络访问，在io线程（子线程）
    call.subscribeOn(Schedulers.io())
            //回到主线程更新UI
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Observer<Weather>() {
                @Override
                public void onSubscribe(@NonNull Disposable d) {
                    Log.i("test", "onSubscribe");
                }
                @Override
                public void onNext(@NonNull Weather weather) {
                    Log.i("test", "rxjava result = " + weather.getHeWeather5()
                    .get(0).getAqi().toString());
                }
                @Override
                public void onError(@NonNull Throwable e) {
                    Log.i("test", "onError");
                }
                @Override
                public void onComplete() {
                    Log.i("test", "onComplete");
                }
            });

# 7.打印请求地址和返回内容 #

使用`Retrofit`网络请求，需要使用到`HttpLoggingInterceptor`类，首先要添加依赖：

compile 'com.squareup.okhttp3:logging-interceptor:3.8.1'

然后初始化`HttpLoggingInterceptor`类：

HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
        @Override
        public void log(String message) {
            //打印retrofit日志
            Log.i("test", "back = " + message);
        }
    });
    //设置打印的等级
    loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

打印的等级有：`NONE、BASIC、HEADERS、BODY`

接着配置`okhttp`的client：

OkHttpClient client = new OkHttpClient.Builder()
            //加入打印类loggingInterceptor
            .addInterceptor(loggingInterceptor)
            .connectTimeout(2000, TimeUnit.SECONDS)
            .readTimeout(2000, TimeUnit.SECONDS)
            .writeTimeout(2000, TimeUnit.SECONDS)
            .build();

最后创建`Retrofit`的时候配置进去：

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://free-api.heweather.com/v5/")
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            //将定义的okhttp配置进入retrofit中
            .client(client)
            .build();

[Link 1]: https://www.heweather.com/documents/api/v5/weather