java遠程獲取圖片生成base64串

說下背景，項目中遇到前端js獲取圖片發生跨域的問題，服務器端又不支持匿名訪問，只能通過服務器獲取圖片base64碼進行展示。代碼如下：下載

Java代碼  

/**
 * 遠程讀取p_w_picpath轉換爲Base64字符串
 * @param imgUrl
 * @return
 */
private String Image2Base64(String imgUrl) {
    URL url = null;
    InputStream is = null;
    ByteArrayOutputStream outStream = null;
    HttpURLConnection httpUrl = null;
    try{
        url = new URL(imgUrl);
        httpUrl = (HttpURLConnection) url.openConnection();
        httpUrl.connect();
        httpUrl.getInputStream();
        is = httpUrl.getInputStream();

        outStream = new ByteArrayOutputStream();
        //創建一個Buffer字符串
        byte[] buffer = new byte[1024];
        //每次讀取的字符串長度，如果爲-1，代表全部讀取完畢
        int len = 0;
        //使用一個輸入流從buffer裏把數據讀取出來
        while( (len=is.read(buffer)) != -1 ){
            //用輸出流往buffer裏寫入數據，中間參數代表從哪個位置開始讀，len代表讀取的長度
            outStream.write(buffer, 0, len);
        }
        // 對字節數組Base64編碼
        return new BASE64Encoder().encode(outStream.toByteArray());
    }catch (Exception e) {
        e.printStackTrace();
    }  下載
    finally{
        if(is != null)
        {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if(outStream != null)
        {
            try {
                outStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if(httpUrl != null)
        {
            httpUrl.disconnect();
        }
    }
    return imgUrl;
}