图像字节数组转换成String类型
File file = new File("C:/abc.png");
InputStream is = new FileInputStream(file);
byte[] byte = new byte[200000];
is.read(byte);
BASE64Encoder encoder = new BASE64Encoder();
String str= encoder.encode(b);
BASE64Decoder base = new BASE64Decoder();
byte[] c =base.decodeBuffer(str);