差分升级（Diff and Patch）

添加maven

    io.sigpipe
    jbsdiff
    1.0

工具类

package cn.stylefeng.guns.core.util;

import io.sigpipe.jbsdiff.Diff;
import io.sigpipe.jbsdiff.InvalidHeaderException;
import org.apache.commons.compress.compressors.CompressorException;

import java.io.*;

public class ByteUtil {
    /**
     * 获得指定文件的byte数组
     */
    public static byte[] getBytes(String filePath){
        byte[] buffer = null;
        try {
            File file = new File(filePath);
            FileInputStream fis = new FileInputStream(file);
            ByteArrayOutputStream bos = new ByteArrayOutputStream(1024);
            byte[] b = new byte[1024];
            int n;
            while ((n = fis.read(b)) != -1) {
                bos.write(b, 0, n);
            }
            fis.close();
            bos.close();
            buffer = bos.toByteArray();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return buffer;
    }

    /**
     * 根据byte数组，生成文件
     */
    public static void getFile(byte[] bfile, String filePath,String fileName) {
        BufferedOutputStream bos = null;
        FileOutputStream fos = null;
        File file = null;
        try {
            File dir = new File(filePath);
            if(!dir.exists()&&dir.isDirectory()){//判断文件目录是否存在
                dir.mkdirs();
            }
            file = new File(filePath+"\\"+fileName);
            fos = new FileOutputStream(file);
            bos = new BufferedOutputStream(fos);
            bos.write(bfile);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (bos != null) {
                try {
                    bos.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        }
    }

    /**
     * 根据文件名和路径生成OutputStream
     * @param filePath
     * @param fileName
     * @return
     */
    public static OutputStream getOutputStream(String filePath,String fileName) {
        OutputStream os = null;
        File file = null;

        try {
            File dir = new File(filePath);
            if(!dir.exists()&&dir.isDirectory()){//判断文件目录是否存在
                dir.mkdirs();
            }
            file = new File(filePath+"\\"+fileName);
            os = new FileOutputStream(file);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
//            if (os != null) {
//                try {
//                    os.close();
//                } catch (IOException e1) {
//                    e1.printStackTrace();
//                }
//            }
        }


        return os;
    }

    public static void main(String [] args) throws IOException, InvalidHeaderException, CompressorException{
        String oldFilePath = "F:\\Downloads\\壁纸\\红小豆2.jpg";
        String newFilePath = "F:\\Downloads\\壁纸\\红小豆4.jpg";
        String outFilePath = "F:\\Downloads\\壁纸";
        String outFileName = "红小豆N.jpg";
        Diff.diff(ByteUtil.getBytes(oldFilePath),ByteUtil.getBytes(newFilePath),ByteUtil.getOutputStream(outFilePath,outFileName));
    }
}