base64与文件相互转换

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.MessageDigest;

import sun.misc.BASE64Encoder;
import sun.misc.BASE64Decoder;

public class Base64ToPicUtil {

	public static String genMd5ByBytes(byte[] bytes) throws Exception {
        String value = null;
        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(bytes);
            byte b[] = md5.digest();
            int i;
            StringBuffer buf = new StringBuffer("");
            for (int offset = 0; offset < b.length; offset++) {
                i = b[offset];
                if (i < 0)
                    i += 256;
                if (i < 16)
                    buf.append("0");
                buf.append(Integer.toHexString(i));
            }
            value = buf.toString();
        } catch (Exception e) {
            e.printStackTrace();
            throw new Exception("文件进行MD5摘要时出现异常。", e);
        }
        return value;
    }
	
	public static String GetImageStr(String imgFilePath) {// 将图片文件转化为字节数组字符串，并对其进行Base64编码处理
        byte[] data = null;

        // 读取图片字节数组
        try {
            InputStream in = new FileInputStream(imgFilePath);
            data = new byte[in.available()];
            in.read(data);
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 对字节数组Base64编码
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(data);// 返回Base64编码过的字节数组字符串
    }

    public static boolean GenerateImage(String imgStr, String imgFilePath) {// 对字节数组字符串进行Base64解码并生成图片
        if (imgStr == null) // 图像数据为空
            return false;
        BASE64Decoder decoder = new BASE64Decoder();
        try {
            // Base64解码
            byte[] bytes = decoder.decodeBuffer(imgStr);
            for (int i = 0; i < bytes.length; ++i) {
                if (bytes[i] < 0) {// 调整异常数据
                    bytes[i] += 256;
                }
            }
            // 生成jpeg图片
            OutputStream out = new FileOutputStream(imgFilePath);
            out.write(bytes);
            out.flush();
            out.close();
            return true;
        } catch (Exception e) {
            return false;
        }
    }


    public static void main(String[] args) {
        // 测试从Base64编码转换为图片文件
//       GenerateImage(strImge, "D:\\test.jpg");
        // 测试从图片文件转换为Base64编码
       // System.out.println(GetImageStr("d:\\11.jpg"));
    }