我正在按照安卓开发者网站上的Volley图片缓存教程进行学习,但在请求和缓存图片时遇到了问题,我猜想是因为我从教程中复制的单例模式。
我的Eclipse在getInstance(this)
处报错,我猜想是因为这是上下文对象而我正在请求图片。
ImageRequest request = new ImageRequest(
url,
new Response.Listener<Bitmap>() {
@Override
public void onResponse(Bitmap bitmap) {
mNetworkImageView = (NetworkImageView) findViewById(R.id.ImageView);
mImageLoader = MySingleton.getInstance(this).getImageLoader();
mNetworkImageView.setImageUrl(IMAGE_URL, mImageLoader);
// mImageLoader = MySingleton.getInstance(this).getImageLoader();
// mImageLoader.get(IMAGE_URL, ImageLoader.getImageListener(mImageView,
// R.drawable.ic_launcher, R.drawable.ic_launcher));
}
},
0,
0,
null,
new Response.ErrorListener() {
public void onErrorResponse(VolleyError error) {
// mImageView.setImageResource(R.drawable.ic_launcher);
}
});
MySingleton.getInstance(this).addToRequestQueue(request);
这是单例模式:
package com.example.p;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.Volley;
import android.content.Context;
import android.graphics.Bitmap;
import android.support.v4.util.LruCache;
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;
}
}
我能够获取图片并以某种方式显示它,但我需要缓存它,所以我猜想将其添加到请求中,对吗?是否有帮助?
mNetworkImageView = (NetworkImageView) findViewById(R.id.ImageView);
mImageLoader = MySingleton.getInstance(this).getImageLoader();
mNetworkImageView.setImageUrl(IMAGE_URL, mImageLoader);
this
的含义,如何在匿名接口实现中使用外部类 - SelvinDiskBasedCache
的资料,但是我没有找到任何有用的教程或者示例,尤其是在一些性能问题方面。非常感谢您提供的信息和帮助。 - Moudiz