java如何将图片缓存到内存中
package tv.ismar.allium.util;import java.lang.ref.SoftReference;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import android.graphics.drawable.Drawable;
import android.os.Handler;
public class AsyncImageLoader {
// 为了加快速度，在内存中开启缓存（主要应用于重复图片较多时，或者同一个图片要多次被访问，比如在ListView时来回滚动）
public Map<String, SoftReference<Drawable>> imageCache = new HashMap<String, SoftReference<Drawable>>();
private ExecutorService executorService = Executors.newFixedThreadPool(5); // 固定五个线程来执行任务
private final Handler handler = new Handler();
public Drawable loadDrawable(final String imageUrl,
final ImageCallback callback) {
// 如果缓存过就从缓存中取出数据
if (imageCache.containsKey(imageUrl)) {
SoftReference<Drawable> softReference = imageCache.get(imageUrl);
if (softReference.get() != null) {
return softReference.get();
}
}
// 缓存中没有图像，则从网络上取出数据，并将取出的数据缓存到内存中
executorService.submit(new Runnable() {
public void run() {
try {
final Drawable drawable = Drawable.createFromStream(
new URL(imageUrl).openStream(), "image.png");
imageCache.put(imageUrl, new SoftReference<Drawable>(
drawable));
handler.post(new Runnable() {
public void run() {
callback.imageLoaded(drawable);
}
});
} catch (Exception e) {
throw new RuntimeException(e);
}
}
});
return null;
}
// 从网络上取数据方法
protected Drawable loadImageFromUrl(String imageUrl) {
try {
return Drawable.createFromStream(new URL(imageUrl).openStream(),
"image.png");
} catch (Exception e) {
throw new RuntimeException(e);
}
}
// 对外界开放的回调接口
public interface ImageCallback {
// 注意 此方法是用来设置目标对象的图像资源
public void imageLoaded(Drawable imageDrawable);
}
}
页:
[1]