深入剖析Android的Volley框架中的图片加载功能

最后,别忘记在AndroidManifest.xml文件中加入访问网络的权限

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

二、源码分析
(一) 初始化Volley请求队列

mReqQueue = Volley.newRequestQueue(mCtx);

主要就是这一行了：

#Volley

public static RequestQueue newRequestQueue(Context context) {
    return newRequestQueue(context, null);
  }

public static RequestQueue newRequestQueue(Context context, HttpStack stack)
  {
    return newRequestQueue(context, stack, -1);
  }
public static RequestQueue newRequestQueue(Context context, HttpStack stack, int maxDiskCacheBytes) {
    File cacheDir = new File(context.getCacheDir(), DEFAULT_CACHE_DIR);

    String userAgent = "volley/0";
    try {
      String packageName = context.getPackageName();
      PackageInfo info = context.getPackageManager().getPackageInfo(packageName, 0);
      userAgent = packageName + "/" + info.versionCode;
    } catch (NameNotFoundException e) {
    }

    if (stack == null) {
      if (Build.VERSION.SDK_INT >= 9) {
        stack = new HurlStack();
      } else {
        // Prior to Gingerbread, HttpUrlConnection was unreliable.
        // See: http://www.easck.com/2011/09/androids-http-clients.html
        stack = new HttpClientStack(AndroidHttpClient.newInstance(userAgent));
      }
    }

    Network network = new BasicNetwork(stack);

    RequestQueue queue;
    if (maxDiskCacheBytes <= -1)
    {
      // No maximum size specified
      queue = new RequestQueue(new DiskBasedCache(cacheDir), network);
    }
    else
    {
      // Disk cache size specified
      queue = new RequestQueue(new DiskBasedCache(cacheDir, maxDiskCacheBytes), network);
    }

    queue.start();

    return queue;
  }

								 
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