@Override
public <T> void write(OutputStream output, T bean) throws Exception {
    ObjectOutputStream oos = null;
    try {
        oos = new ObjectOutputStream(output);
        oos.writeObject(bean);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        IOUtils.closeQuietly(oos);
    }
}
@Override
public <T> T read(InputStream input, Class<T> entityClass) throws Exception {
    ObjectInputStream ois = null;
    try {
        ois = new ObjectInputStream(input);
        return  (T) ois.readObject();
    } catch (IOException | ClassNotFoundException e) {
        e.printStackTrace();
        return null;
    } finally {
        IOUtils.closeQuietly(ois);
    }
}

OkHttpClient mOkHttpClient = new OkHttpClient();
File cacheDirectory = new File(context.getApplicationContext()
           .getCacheDir().getAbsolutePath(), "HttpCache");  //指定缓存路径
Cache cache = new Cache(cacheDirectory, 20 * 1024 * 1024);  //指定缓存大小
mOkHttpClient.setCache(cache);

public abstract class BaseApi {
    //设缓存有效期为两个星期
    protected static final long CACHE_STALE_SEC = 60 * 60 * 24 * 14;
    //查询缓存的Cache-Control设置
    protected static final String CACHE_CONTROL_CACHE = "only-if-cached, max-stale=" + CACHE_STALE_SEC;
    //查询网络的Cache-Control设置
    protected static final String CACHE_CONTROL_NETWORK = "max-age=0";
}

public class UserApi extends BaseApi{
    //定义接口
    private interface UserService {
        //POST方法没有缓存，适用于更新操作的接口
        @FormUrlEncoded
        @POST("user/user_updateUserName")
        Observable<BaseResp> updateUserName(@Field("userName") String userName);
        
        //用@Header设置Cache-Control
        @GET("user/user_queryProfile")
        Observable<UserProfileResp> queryProfile(@Header("Cache-Control") String cacheControl,
                                                 @Query("userId") int userId);
        
    }
    protected static final UserService service = getRetrofit().create(UserService.class);
    //更新用户名接口
    public static Observable<BaseResp> updateUserName(String userName){
        return service.updateUserName(userName);
    }
    //查询用户信息网络接口
    public static Observable<UserProfileResp> queryProfile(int userId){
        return service.queryProfile(CACHE_CONTROL_NETWORK, userId);
    }
    //查询用户信息缓存接口
    public static Observable<UserProfileResp> queryProfileCache(int userId){
        return service.queryProfile(CACHE_CONTROL_CACHE, userId);
    }
}

public abstract class BaseApi {
	public static final String API_SERVER = "服务器地址"
	private static final OkHttpClient mOkHttpClient = new OkHttpClient();
    private static Retrofit mRetrofit;
	protected static Retrofit getRetrofit() {
	        if (Retrofit == null) {
		        Context context = Application.getInstance().getApplicationContext();
	            //设定30秒超时
	            mOkHttpClient.setConnectTimeout(30, TimeUnit.SECONDS);
	            //设置拦截器，以用于自定义Cookies的设置
	            mOkHttpClient.networkInterceptors()
				            .add(new CookiesInterceptor(context));
		        //设置缓存目录
	            File cacheDirectory = new File(context.getCacheDir()
							            .getAbsolutePath(), "HttpCache");
	            Cache cache = new Cache(cacheDirectory, 20 * 1024 * 1024);
	            mOkHttpClient.setCache(cache);
	            //构建Retrofit
	            mRetrofit = new Retrofit.Builder()
			            //配置服务器路径
	                    .baseUrl(API_SERVER + "/")  
	                    //设置日期解析格式，这样可以直接解析Date类型
	                    .setDateFormat("yyyy-MM-dd HH:mm:ss")  
	                    //配置转化库，默认是Gson
	                    .addConverterFactory(ResponseConverterFactory.create())
	                    //配置回调库，采用RxJava
	                    .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
	                    //设置OKHttpClient为网络客户端
	                    .client(mOkHttpClient)
	                    .build();
	        }
	        return mRetrofit;
	    }
}