/**
 * 根據圖片地址獲得資料的位元組流
 * @param strUrl 網路連線地址
 * @return
 */
public static byte[] getImageFromNetByUrl(String strUrl){
    try {
        URL url = new URL(strUrl);
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setRequestMethod("GET");
        conn.setConnectTimeout(3 * 1000);
        InputStream inStream = conn.getInputStream();//通過輸入流獲取圖片資料
        byte[] btImg = readInputStream(inStream);//得到圖片的二進位制資料
        return btImg;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

/** 
 * 從輸入流中獲取資料 
 * @param inStream 輸入流 
 * @return 
 * @throws Exception 
 */  
public static byte[] readInputStream(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);  
    }  
    inStream.close();  
    return outStream.toByteArray();  
} 


兩個方法一起使用