java远程获取图片生成base64串

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       说下背景，项目中遇到前端js获取图片发生跨域的问题，服务器端又不支持匿名访问，只能通过服务器获取图片base64码进行展示。代码如下：

/**
 * 远程读取image转换为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();
		//创建一个Buffer字符串
		byte[] buffer = new byte[1024];
		//每次读取的字符串长度，如果为-1，代表全部读取完毕
		int len = 0;
		//使用一个输入流从buffer里把数据读取出来
		while( (len=is.read(buffer)) != -1 ){
			//用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
			outStream.write(buffer, 0, len);
		}
		// 对字节数组Base64编码
		return new BASE64Encoder().encode(outStream.toByteArray());
	}catch (Exception e) {
		e.printStackTrace();
	}
	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;
}