Android图片的下载和展示

public class DownloadSplashThread extends Thread
{
    private String url;
    private Context context;

    public DownloadSplashThread(Context context, String url)
    {
        this.url = url;
        this.context = context;
    }
    @Override
    public void run() {
        super.run();

        byte[] data = null;
        try {
            data = new ImageAction(context).getImage(url);

        } catch (Exception e) {
            e.printStackTrace();
        }

        if(data != null)
        {
            Bitmap mBitmap = null;
            try {
                mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
            }catch (OutOfMemoryError e)
            {
                System.gc();
                System.runFinalization();
            }

            if(mBitmap != null)
            {
                try {
                    new ImageAction(context).saveFile(context, mBitmap, "splash.jpg");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        return;
    }
}

public class ImageAction
{
    //根据url获取图片
    public byte[] getImage(String path) throws Exception{
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setConnectTimeout(5 * 1000);
        conn.setRequestMethod("GET");
        InputStream inStream = conn.getInputStream();
        if(conn.getResponseCode() == HttpURLConnection.HTTP_OK){
            return readStream(inStream);
        }
        return null;
    }

    public static byte[] readStream(InputStream inStream) throws Exception{
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while( (len=inStream.read(buffer)) != -1){
            outStream.write(buffer, 0, len);
        }
        outStream.close();
        inStream.close();
        return outStream.toByteArray();
    }

    public void saveFile(Context context, Bitmap bm, String fileName) throws IOException {
        // 这是将文件保存到内部存储中
        File file = new File(context.getFilesDir(), "FileName.png");
        OutputStream outStream = new FileOutputStream(file);
        bm.compress(Bitmap.CompressFormat.PNG, 80, outStream);
        outStream.flush();
        outStream.close();

        //或者也可以考虑存储到外部存储(SD卡)中,这需要申请外部存储读写权限,用户可能会拒绝
        //而且App删除后这些文件依然保留,不建议使用
        private final static String ALBUM_PATH
        = Environment.getExternalStorageDirectory() + "/com.brand.ushopping/";

    public void saveFile(Bitmap bm, String fileName) throws IOException {
        File dirFile = new File(ALBUM_PATH);
        if(!dirFile.exists()){
            dirFile.mkdir();
        }
        File myCaptureFile = new File(ALBUM_PATH + fileName);
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));
        bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);
        bos.flush();
        bos.close();
    }
    
}

//读取内部存储的图片
public Bitmap loadImage(Context context)
{
    try
    {
        File file = new File(context.getFilesDir(), "Filename");
        if (file.exists()) {
            FileInputStream fileInputStream = new FileInputStream(file);
            Bitmap bitmap = BitmapFactory.decodeStream(fileInputStream);
            return bitmap;
        }

    }catch (Exception e)
    {
        e.printStackTrace();
    }

    return null;
}

//读取SD卡中的图片
public Bitmap loadImage(String fileName)
{
    String url = ALBUM_PATH + fileName;
    try
    {
        File file = new File(url);
        if (file.exists()) {
            Bitmap bitmap = BitmapFactory.decodeFile(url);
            return bitmap;
        }

    }catch (Exception e)
    {
        e.printStackTrace();
    }
    return null;
}

Bitmap bitmap = loadImage(SplashAdActivity.this);
imageView.setImageBitmap(bitmap);