Android异步加载图片，解决图片过大OOM问题

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.lang.ref.SoftReference;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Handler.Callback;
import android.os.Message;
import android.widget.ImageView;

/**
*
* 功能说明：异步加载图片
*
* @author Jack.wang
*
*/
public class AsyncImageLoaderCore
{

public Context context; // 做本地缓存时会用到
public HashMap<String, SoftReference<Bitmap>> imageCache;// 软引用集合

public AsyncImageLoaderCore(Context context)
{
this.context = context;
this.imageCache = new HashMap<String, SoftReference<Bitmap>>();
}

public Bitmap loadBitmap(final String imageUrl, final ImageView imageView, final ImageCallback imageCallback)
{
if (imageCache.containsKey(imageUrl))
{
SoftReference<Bitmap> softReference = imageCache.get(imageUrl);
if (softReference.get() != null)
return softReference.get();
}

final Handler handler = new Handler(new Callback()
{

@Override
public boolean handleMessage(Message msg)
{
imageCallback.imageLoaded((Bitmap) msg.obj, imageView, imageUrl);
return false;
}
});

new Thread()
{
@Override
public void run()
{
Bitmap bitmap = null;
try
{
bitmap = getHttpBitmap(imageUrl);
}
catch (Exception e)
{
e.printStackTrace();
return;
}

if (null != bitmap)
{
imageCache.put(imageUrl, new SoftReference<Bitmap>(bitmap));
handler.sendMessage(handler.obtainMessage(0, bitmap));
}
}
}.start();

return null;
}

private final int MAX_PIC_LENGTH = 200000;// 最大字节长度限制[可调,最好不要超过200000]
private final int SAMPLE_SIZE = 14;// 裁剪图片比列(1/14)[可调]

/**
* 获取网络图片
*/
private Bitmap getHttpBitmap(String imgUrl) throws Exception
{
URL htmlUrl = new URL(imgUrl);
URLConnection connection = htmlUrl.openConnection();
HttpURLConnection conn = (HttpURLConnection) connection;

if (conn.getResponseCode() == HttpURLConnection.HTTP_OK)
{
InputStream inputStream = conn.getInputStream();

byte[] bytes = changeToBytes(inputStream);

if(bytes.length < MAX_PIC_LENGTH)
{
return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
}
else if(bytes.length < MAX_PIC_LENGTH * SAMPLE_SIZE)
{
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = false;
options.inSampleSize = SAMPLE_SIZE;

return BitmapFactory.decodeByteArray(bytes, 0, bytes.length, options);
}
}

return null;
}

/**
* 将流转换成字节数组
*/
public byte[] changeToBytes(InputStream inputStream) throws Exception
{
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];// 每次读取的字节长度
int len = 0;
while((len = inputStream.read(buffer)) != -1)
{
outputStream.write(buffer, 0, len);
}
inputStream.close();
return outputStream.toByteArray();
}

/**
* 异步加载资源回调接口
*/
public interface ImageCallback
{
public void imageLoaded(Bitmap bitmap, ImageView imageView, String imageUrl);
}

}