Android中volley封装实践记录

砸漏

发布于 2020-11-04 10:28:19

5110

发布于 2020-11-04 10:28:19

前言

在项目中一般使用使用volley方式如下，用起来给人一种很乱的感觉，于是一种盘它的想法油然而生。

public void get() {
String url = "https://tcc.taobao.com/cc/json/mobile_tel_segment.htm?tel=......";
StringRequest request = new StringRequest(Request.Method.GET, url, new Response.Listener<String () {

   @Override

   public void onResponse(String s) {

    Toast.makeText(MainActivity.this,s,Toast.LENGTH_SHORT).show();

   }

  }, new Response.ErrorListener() {

   @Override

   public void onErrorResponse(VolleyError volleyError) {

    Toast.makeText(MainActivity.this,volleyError.toString(),Toast.LENGTH_SHORT).show();

   }

  });

  request.setTag("abcGet");

  MyApplication.getHttpQueues().add(request);

 }

首先看一下我封装后的使用例子:

 private void initData() {
  NewsApi.getInfo(new NetCallback<News () {
   @Override
   public void OnSuccess(final News result) {
    mAdapter.setData(result.getResult().getData());
   }
   @Override
   public void OnError(RestfulError error) {
   }
  });
 }

有没有看起来很舒服的感觉。好吧，让我开始盘它吧！

1.首先我先去写了一个基类，用来创建一个新的request并把它加入到volley内部封装的请求队列中，代码如下：

public abstract class AuthenticatedRequestBase<T  extends Request<T  {
 private final static String TAG = "AuthenticatedRequestBase";
 private static final int TIME_OUT = 30000;
 private static final int MAX_RETRIES = 1;
 private static final float BACKOFF_MULT = 2f;
 protected Context mContext;
 protected RequestQueue mRequestQueue;

 /**
  * 创建新的请求，并把请求加入到请求队列requestQueue中
  *
  * @param method
  * @param url
  * @param cache
  * @param errorListener
  */
 @SuppressLint("LongLogTag")
 public AuthenticatedRequestBase(int method, String url, boolean cache, Response.ErrorListener errorListener) {
  super(method, url, errorListener);
  //this.setShouldCache(cache);
  this.setRetryPolicy(new DefaultRetryPolicy(
    TIME_OUT,
    MAX_RETRIES,
    BACKOFF_MULT));

  mRequestQueue = YZ.getInstance().getRequestQueue();
  if (mRequestQueue == null) {
   throw new IllegalArgumentException("mRequestQueue can't be null");
  }

  mContext = YZ.getInstance().getContext();
  if (mContext == null) {
   throw new IllegalArgumentException("mContext can't be null");
  }

  //如果重新发出服务器请求的时候，需要清除之前的缓存。
  if (!cache) {
   Cache volleyCache = mRequestQueue.getCache();
   Cache.Entry cacheEntry = volleyCache.get(url);

   if (cacheEntry != null) {
    volleyCache.remove(url);
    Log.d(TAG, "remove volley cache:" + url);
   }
  }
  mRequestQueue.add(this);
 }

 /**
  * 重写这个方法，可以在http请求头里面加入token，客户端能接受的数据类型
  *
  * @return
  * @throws AuthFailureError
  */
 @CallSuper
 @Override
 public Map<String, String  getHeaders() throws AuthFailureError {
  Map<String, String  headers = new HashMap< ();
  String token = "............";
  //headers.put("Authorization", "bearer " + token);
  //针对Get方法，申明接受的enum类型
  // headers.put("Accept", "charset=utf-8");
  return headers;
 }

 /**
  * 网络错误问题统一处理
  *
  * @param volleyError
  * @return
  */
 @CallSuper
 @Override
 protected VolleyError parseNetworkError(VolleyError volleyError) {
  return super.parseNetworkError(volleyError);
 }
}

代码注释比较清晰，就不在赘述。

2.以get方法为例，新建一个GetRequest去继承这个基类，并出解析结果：

public class GetRequest<TResponse  extends AuthenticatedRequestBase<TResponse  {
private final Response.Listener<TResponse  listener;
private final Class<TResponse  clazz;
private final static String TAG = "GetRequest";
private String mUrl;
private NetCallback<TResponse  cb;
private boolean cacheHit;
public GetRequest(String url, Class<TResponse  clazz, boolean cache, NetCallback<TResponse  callback) {
super(Request.Method.GET, url, cache, callback.getErrorListener());
this.listener = callback.getSuccessListener();
this.clazz = clazz;
this.mUrl = url;
this.cb = callback;
//无网络时300ms后返回callback
if (!NetUtils.isConnect(mContext) && mRequestQueue.getCache().get(url) == null) {
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
cb.OnNetworkOff();
}
}, 300);
}
}
/**
* 这个是缓存的标记，与本地缓存相关
* @param tag
*/
@Override
public void addMarker(String tag) {
super.addMarker(tag);
cacheHit = tag.equals("cache-hit");
}
@Override
protected Response<TResponse  parseNetworkResponse(NetworkResponse response) {
Gson gson = new Gson();
//无网络时，使用本地缓存,通过url去匹配缓存，volley sdk是通过url创建不同的文件来实现缓存的
if (!NetUtils.isConnect(mContext) && mRequestQueue.getCache().get(mUrl) != null) {
String json = new String(mRequestQueue.getCache().get(mUrl).data);
Log.d(TAG, "url==" + mUrl + ",json" + json);
cb.fResponseCacheStatus = ResponseCacheStatus.StaleFromCache;
return Response.success(gson.fromJson(json, clazz), parseCacheHeaders(response));
}
//数据是否有更新
try {
if (response.statusCode == 304) {
//服务端返回缓存数据
cb.fResponseCacheStatus = ResponseCacheStatus.NotModifiedFromServer;
} else if (response.statusCode == 200) {
if (cacheHit) {
//使用本地缓存
cb.fResponseCacheStatus = ResponseCacheStatus.FreshFromCache;
} else {
//使用服务端更新数据
cb.fResponseCacheStatus = ResponseCacheStatus.NewFromServer;
}
} else {
cb.fResponseCacheStatus = ResponseCacheStatus.NewFromServer;
}
Log.d(TAG, "fResponseCacheStatus = " + cb.fResponseCacheStatus);
String json = new String(response.data, parseCharset(response.headers));
return Response.success(gson.fromJson(json, clazz), parseCacheHeaders(response));
} catch (UnsupportedEncodingException | JsonSyntaxException e) {
return Response.error(new ParseError(e));
}
}
@Override
protected void deliverResponse(TResponse response) {
listener.onResponse(response);
}
@Override
protected VolleyError parseNetworkError(VolleyError volleyError) {
return super.parseNetworkError(volleyError);
}
}

3.上面只做了返回成功的处理方式，返回失败时由NetCallback内部统一处理：

@UiThread
public abstract class NetCallback<TResponse  {
public ResponseCacheStatus fResponseCacheStatus = ResponseCacheStatus.NewFromServer;
private String TAG = this.getClass().getSimpleName();
public boolean enableAutomaticToastOnError = true;
public NetCallback() {
}
public NetCallback(boolean enableAutomaticToastOnError) {
this.enableAutomaticToastOnError = enableAutomaticToastOnError;
}
public abstract void OnSuccess(TResponse result);
public abstract void OnError(RestfulError error);
public void OnNetworkOff() {
//do nothing ,use it according to requirement
}
public Response.Listener<TResponse  getSuccessListener() {
return new Response.Listener<TResponse () {
@Override
public void onResponse(TResponse result) {
OnSuccess(result);
}
};
}
public Response.ErrorListener getErrorListener() {
return new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
if (volleyError instanceof TimeoutError) {
Log.e(TAG, "networkResponse == null");
//volley TimeoutError
OnError(new RestfulError());
}
if (volleyError.networkResponse != null) {
int statusCode = volleyError.networkResponse.statusCode;
String errorMessage = new String(volleyError.networkResponse.data);
switch (statusCode) {
case 401:
//post a Permission authentication failed event
break;
default:
Log.d(TAG, "errorMessage =" + errorMessage);
try {
RestfulError error = new Gson().fromJson(errorMessage, RestfulError.class);
if (enableAutomaticToastOnError && error.getCode() != null) {
//toast(error.ExceptionMessage); //toast it in main thread
}
OnError(error);
} catch (Exception e) {
OnError(new RestfulError());
Log.d(TAG, "e =" + e.toString());
}
break;
}
}
}
};
}
}

4.注意到没有，在AuthenticatedRequestBase内部有一个环境类YZ,主要负责获取项目主程序中的context和请求队列：

public class YZ implements AppRequestQueue {
private static final int DEFAULT_VOLLEY_CACHE_SIZE = 100 * 1024 * 1024;
private Context context;
private int cacheSize;
private YZ() {
}
@Override
public RequestQueue getRequestQueue() {
return Volley.newRequestQueue(context, cacheSize);
}
public Context getContext() {
return context;
}
private static class SingletonHolder {
private static YZ instance = new YZ();
}
public static YZ getInstance() {
return SingletonHolder.instance;
}
/**
* need a app context
*
* @param appContext
*/
public void init(final Context appContext) {
init(appContext, DEFAULT_VOLLEY_CACHE_SIZE);
}
/**
* @param appContext
* @param cacheSize
*/
public void init(final Context appContext, final int cacheSize) {
this.context = appContext;
this.cacheSize = cacheSize;
}
}

这个类需要在app的application中初始化：

public class BaseApp extends Application {
public String TAG = this.getClass().getSimpleName();
public static Context applicationContext;
public static Executor threadPool;
public static final int THREAD_POOL_SIZE = 3;
public static final boolean isDebug = BuildConfig.BUILD_TYPE.equals("debug");
@Override
public void onCreate() {
super.onCreate();
applicationContext = getApplicationContext();
threadPool = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
initNet();
}
private void initNet() {
YZ.getInstance().init(this);
}
public Context getInstance() {
return applicationContext;
}
}

4.现在可以开始外部封装啦。

public class NewsApi {
public static void getInfo(NetCallback<News  callback) {
new GetRequest< (INetConstant.NEWS, News.class, true, callback);
}
}

还有一点，volley的缓存实现需要服务端配合在http请求的Cache-control: max-age配置支持缓存，并设定好缓存时间，否则无法生效。

最后贴一张效果图:

图片发自简书App

到此结束，后期还会进行优化，代码在[github] (https://github.com/daydaydate/sample（本地下载）)。

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，如果有疑问大家可以留言交流，谢谢大家对ZaLou.Cn的支持。

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原始发表：2020-09-11 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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