volley的正確使用方式

源碼下載：https://github.com/heinika/android-volley

導入的三種方式：

在dependencies下搜索

導入源碼包，import model  在dependencies導入model

導入jar，放在lib目錄下

networkimageview防止內存溢出

先下載，判斷內存，不夠就壓縮圖片

volley實現方式（如上圖）：

先找緩存

後訪問網絡

使用起來非常簡單：

先寫一個單例，保證只有一個RequestQueue

public class MySingleton {
private static MySingleton mInstance;
private RequestQueue mRequestQueue;
private ImageLoader mImageLoader;
private static Context mCtx;

private MySingleton(Context context) {
mCtx = context;
mRequestQueue = getRequestQueue();

mImageLoader = new ImageLoader(mRequestQueue,
new ImageLoader.ImageCache() {
private final LruCache<String, Bitmap>
cache = new LruCache<String, Bitmap>(20);

@Override
                    public Bitmap getBitmap(String url) {
return cache.get(url);
                    }

@Override
                    public void putBitmap(String url, Bitmap bitmap) {
cache.put(url, bitmap);
                    }
                });

    }

public static synchronized MySingleton getInstance(Context context) {
if (mInstance == null) {
mInstance = new MySingleton(context);
        }
return mInstance;
    }

public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
// getApplicationContext() is key, it keeps you from leaking the
            // Activity or BroadcastReceiver if someone passes one in.
            mRequestQueue = Volley.newRequestQueue(mCtx.getApplicationContext());
        }
return mRequestQueue;
    }

public <T> void addToRequestQueue(Request<T> req) {
        getRequestQueue().add(req);
    }

public ImageLoader getImageLoader() {
return mImageLoader;
    }
}

再在主函數中使用

case R.id.button_volley_connect:
/**
                 * 應該創建單例防止出現多個RequestQueue
                 */
//                RequestQueue queue = Volley.newRequestQueue(getApplicationContext());
                MySingleton singleton = MySingleton.getInstance(getApplicationContext());
                RequestQueue queue = singleton.getRequestQueue();
                StringRequest request = new StringRequest(Request.Method.POST, "http://192.168.0.30:8080/MyWebTest/MyTestServerlet", new Response.Listener<String>() {
@Override
                    public void onResponse(String response) {
mTextViewVolley.setText(response);
                    }
                }, new Response.ErrorListener() {
@Override
                    public void onErrorResponse(VolleyError error) {
mTextViewVolley.setText("網絡連接失敗"+error.toString());
                    }
                }){
@Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        HashMap map = new HashMap();
                        map.put("username","heinika");
return map;
                    }
                };
                singleton.addToRequestQueue(request);
break;
case R.id.button_networkimageview:
mNetworkImageView.setImageUrl("http://f.hiphotos.baidu.com/news/w%3D638/sign=38984923f5deb48ffb69a2ddc81e3aef/b03533fa828ba61e6db11b6d4734970a304e5911.jpg"
                        ,MySingleton.getInstance(getApplicationContext()).getImageLoader());
break;
default:
break;
        }
    }