java如何通过流读取图片做base64编码

<img src="data:image/png;base64,xxxxxxxxxxxxxxxxxxxxxxx"/>

package com.xxx.test;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import sun.misc.BASE64Encoder;
public class ReadImageInputStreamDemo {
	public static void main(String[] args) {
		InputStream inputStream = null; 
		ByteArrayOutputStream outputStream = null;
		try {
			String fileName = "/Users/buejee/Downloads/电路.jpeg";
			String mediaType = fileName.substring(fileName.lastIndexOf(".")+1);
			File imageFile= new File(fileName);
			boolean exists = imageFile.exists();
			if(exists) {
				inputStream = new FileInputStream(fileName);
				outputStream = new ByteArrayOutputStream();
				int len;
				byte[] buf = new byte[1024];
				while((len = inputStream.read(buf))!=-1) {
					outputStream.write(buf, 0, len);
				}
				outputStream.flush();
				byte[] data = outputStream.toByteArray();
				BASE64Encoder encoder = new BASE64Encoder();
				String encodeStr = encoder.encode(data);
				encodeStr = "data:image/"+mediaType+";base64,"+encodeStr;
				System.out.println(encodeStr);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			try {
				if(inputStream!=null) {
					inputStream.close();
				}
				if(outputStream!=null) {
					outputStream.close();
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}