ImageLoader的LruBitmapCache與http緩存(具有默認實現DiskBasedCache)不同。在lru緩存中,你會緩存eaxct位圖的大小,否則當你需要放入一個容器時,你需要在圖像數據數組上執行一些操作。但是http緩存或DiskBasedCache緩存原始響應。
因此,無論如何你打2個電話的原因可能是因爲你的圖像響應沒有緩存頭允許緩存。但是,您可以更改此行爲並強制緩存。您需要自定義ImageLoader,因爲這是創建圖像請求的人。您必須覆蓋「makeImageRequest」:
...
mImageLoader = new ImageLoader(this.mRequestQueue,
new LruBitmapCache()) {
@Override
protected Request<Bitmap> makeImageRequest(String requestUrl, int maxWidth, int maxHeight,
ScaleType scaleType, final String cacheKey) {
return new ImageRequest(requestUrl, new Listener<Bitmap>() {
@Override
public void onResponse(Bitmap response) {
onGetImageSuccess(cacheKey, response);
}
}, maxWidth, maxHeight, scaleType, Config.RGB_565, new ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
onGetImageError(cacheKey, error);
}
}){
@Override
public Response<Bitmap> parseNetworkResponse(NetworkResponse response) {
Response<Bitmap> resp = super.parseNetworkResponse(response);
if(!resp.isSuccess()) {
return resp;
}
long now = System.currentTimeMillis();
Cache.Entry entry = resp.cacheEntry;
if(entry == null) {
entry = new Cache.Entry();
entry.data = response.data;
entry.responseHeaders = response.headers;
}
entry.ttl = now + 30l * 24 * 60 * 60 * 1000; //keeps cache for 30 days
entry.softTtl = now + 24 * 60 * 60 * 1000; // keeps valid(no refresh) for 1 day
return Response.success(resp.result, entry);
}
};
}
};
...