compile 'com.squareup.okhttp3:okhttp:3.4.2'

public class MainActivity extends Activity {
    private String tag = "MainActivity";
    private Context mContext;
    private OkHttpClient client;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = this;
        initData();
    }

    private void initData() {
        client = getOkHttpClient();

        // 同步Get请求
        //getRequest();
        // 异步Get请求
        getAsyncRequest();
    }

    private OkHttpClient getOkHttpClient() {
        // 设置缓存
        Cache cache = new Cache(mContext.getCacheDir(), 1024 * 1024 * 10);

        OkHttpClient client = new OkHttpClient.Builder()
                .cache(cache)
                .connectTimeout(20, TimeUnit.SECONDS)
                .readTimeout(20, TimeUnit.SECONDS)
                .build();
        return client;
    }

    private void getRequest() {
        new Thread() {
            @Override
            public void run() {
                String url = "http://www.baidu.com";
                Request request = new Request.Builder().url(url).build();
                try {
                    // execute为同步请求，所以这里放在了Thread里。
                    Response response = client.newCall(request).execute();
                    if (response.isSuccessful()) {
                        String result;
                        if (response.cacheResponse() == null) {
                            result = response.body().string();
                        } else {
                            result = response.body().string();
                        }

                        Log.i(tag, result);

                    } else {
                        Log.i(tag, "request failure");
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }.start();
    }

    private void getAsyncRequest() {
        String url = "http://www.baidu.com";
        Request request = new Request.Builder().url(url).build();
        // enqueue 加入调度,onResponse在工作线程执行
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                Log.i(tag, "onFailure");
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if(response.isSuccessful()){
                    String result;
                    if (response.cacheResponse() == null) {
                        result = response.body().string();
                    } else {
                        result = response.body().string();
                    }

                    Log.i(tag, result);
                }
            }
        });
    }
}