课前准备

• 修改 LogUtils ：把 Class clazz 改成 Object object

public class LogUtils {

    private static int currentLev = 4;
    private static final int DEBUG_LEV = 4;
    private static final int INFO_LEV = 3;
    private static final int WARNING_LEV = 2;
    private static final int ERROR_LEV = 1;

    public static void d(Object object,String log) {
        if(currentLev >= DEBUG_LEV) {
            Log.d(object.getClass().getSimpleName(),log);
        }
    }

    public static void i(Object object,String log) {
        if(currentLev >= INFO_LEV) {
            Log.i(object.getClass().getSimpleName(),log);
        }
    }

    public static void w(Object object,String log) {
        if(currentLev >= WARNING_LEV) {
            Log.w(object.getClass().getSimpleName(),log);
        }
    }

    public static void e(Object object,String log) {
        if(currentLev >= ERROR_LEV) {
            Log.e(object.getClass().getSimpleName(),log);
        }
    }
}

• 添加网络访问权限

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

课堂笔记

• 在 model 文件夹下创建接口 Api

public interface Api {
    @GET("discovery/categories")
    Call<Categories> getCategories();
}

• 在 utils 文件夹下创建单例类 RetrofitManager

public class RetrofitManager {
    private static final RetrofitManager ourInstance = new RetrofitManager();
    private final Retrofit mRetrofit;

    public static RetrofitManager getInstance() {
        return ourInstance;
    }

    private RetrofitManager() {
        mRetrofit = new Retrofit.Builder()
                .baseUrl(Constant.BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();
    }

    public Retrofit getRetrofit() {
        return mRetrofit;
    }
}

常量 BASE_URL 在 utils 文件夹下常量类 Constant 中创建

public class Constant {

    public static final String BASE_URL = "https://api.sunofbeach.net/shop/api/";
}

• 获取 请求分类数据 的代码

@Override
    public void getCategories() {
        Retrofit retrofit = RetrofitManager.getInstance().getRetrofit();
        Api api = retrofit.create(Api.class);
        Call<Categories> task = api.getCategories();
        task.enqueue(new Callback<Categories>() {
            @Override
            public void onResponse(Call<Categories> call, Response<Categories> response) {
                int code = response.code();
                LogUtils.d(HomePresenterImpl.this, "HomePresenterImpl code ----->" + code);
                if (code == HttpURLConnection.HTTP_OK) {
                    //请求成功
                    Categories body = response.body();
                    LogUtils.d(HomePresenterImpl.this, "HomePresenterImpl body ----->" + body.toString());
                } else {
                    //请求失败
                    LogUtils.i(HomePresenterImpl.this, "请求失败....");
                }
            }

            @Override
            public void onFailure(Call<Categories> call, Throwable t) {
                //请求失败
                LogUtils.i(HomePresenterImpl.this, "请求失败....");
            }
        });
    }

学习感悟

• 这节课如果有同学程序一直崩，需要在 module gradle 中 android 下加以下代码

compileOptions{
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

• Android 初学者一名，请老师和各位同学讨论指正