App.java

package com.lh.fly;

import android.app.Application;
import android.content.Context;
import android.util.DisplayMetrics;

import com.lh.fly.api.Constants;
import com.lh.fly.common.Config;
import com.lh.fly.common.assist.Network;
import com.squareup.okhttp.Cache;
import com.squareup.okhttp.OkHttpClient;

import java.io.File;

import retrofit.RequestInterceptor;
import retrofit.RestAdapter;
import retrofit.client.OkClient;

public class App extends Application {

    public static int SCREEN_WIDTH;
    public static int SCREEN_HEIGHT;

    private static RestAdapter mRestAdapter;
    private static Context sContext;

    @Override
    public void onCreate() {
        super.onCreate();

        sContext = getApplicationContext();
        init();
    }

    private void init() {
        DisplayMetrics dm =getResources().getDisplayMetrics();
        SCREEN_WIDTH = Math.min(dm.widthPixels, dm.heightPixels);
        SCREEN_HEIGHT = Math.max(dm.widthPixels, dm.heightPixels);

        OkHttpClient client = new OkHttpClient();
        File cacheDirectory = new File(Config.CACHE_DIR);
        if (!cacheDirectory.exists()) {
            cacheDirectory.mkdirs();
        }
        final Cache cache = new Cache(cacheDirectory, Config.CACHE_SIZE);
        client.setCache(cache);
        mRestAdapter = new RestAdapter.Builder()
                .setEndpoint(Constants.BASE_URL)
                .setClient(new OkClient(client))
                .setRequestInterceptor(new RequestInterceptor() {
                    @Override
                    public void intercept(RequestFacade request) {
                        if (Network.isConnected(getApplicationContext())) {
                            int maxAge = 2; // read from cache for 1 minute
                            request.addHeader(
                                    "Cache-Control",
                                    "public, max-age=" + maxAge);
                        } else {
                            int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
                            request.addHeader(
                                    "Cache-Control",
                                    "public, only-if-cached, max-stale=" + maxStale);
                        }
                    }
                })
                .build();
    }

    public static RestAdapter getRestAdapter() {
        return mRestAdapter;
    }

    public static <T> T getService(Class<T> service) {
        return getRestAdapter().create(service);
    }

    public static Context getAppContext() {
        return sContext;
    }

}