大文件的分割与合并

public class  {
    public void mergePartFiles(String dirpath, String partFileSuffix, String mergeFileName) throws Exception {
        ArrayList<File> partFiles = getDirFiles(dirpath, partFileSuffix);
        Collections.sort(partFiles, new FileComparator());
        int partFileSize = (int) partFiles.get(0).length();
        RandomAccessFile randomAccessFile = new RandomAccessFile(mergeFileName, "rw");
//        System.out.println("文件长度"+partFileSize * (partFiles.size() - 1) + partFiles.get(partFiles.size() - 1).length());
        randomAccessFile.setLength(partFileSize * (partFiles.size() - 1) + partFiles.get(partFiles.size() - 1).length());
        randomAccessFile.close();
        for (File partFile : partFiles) {
            System.out.println(partFile.getName() + partFile.length());
        }
        ThreadPoolExecutor threadPool = new ThreadPoolExecutor(partFiles.size(), partFiles.size() * 3, 1, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(partFiles.size() * 2));
        for (int i = 0; i < partFiles.size(); i++) {
            threadPool.execute(new MergeRunnable(i * partFileSize, mergeFileName, partFiles.get(i)));
        }
        System.out.println("成功了！！！");
    }
    /**
     * 获得目录下的文件
     *
     * @param dirpath
     * @param suffix
     * @return
     */
    private ArrayList<File> getDirFiles(String dirpath, final String suffix) {
        File path = new File(dirpath);
        File[] fileArr = path.listFiles(new FilenameFilter() {
            
            public boolean accept(File dir, String name) {
                String lowerName = name.toLowerCase();
                String filesuffix = suffix.toLowerCase();
                if (lowerName.endsWith(filesuffix)) {
                    return true;
                } else
                    return false;
            }
        });
        ArrayList<File> files = new ArrayList<File>();
        for (File file : fileArr) {
            if (file.isFile()) {
                files.add(file);
            }
        }
        return files;
    }
    public List<String> splitBySize(String fileName, int count) throws Exception {
        List<String> parts = new ArrayList<String>();
        File file = new File(fileName);
//        int byteSize = (int) Math.ceil(file.length() / (double)count);
        List<Integer> bytes = new ArrayList<Integer>();
        int countLen = (count+"").length();
        testLen((int) file.length(), count, bytes);
        ThreadPoolExecutor threadpool = new ThreadPoolExecutor(count, count * 3, 1, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(count * 2));
        for (int i = 0; i < count; i++) {
            String partFileName = file.getName() + "_" + leftPad(i+"",countLen,'0') + ".part";
            threadpool.execute(new SplitRunnable(bytes.get(i), i * bytes.get(i == 0 ? 0 : i - 1), partFileName, file));
            parts.add(partFileName);
        }
        return parts;
    }
    private String leftPad(String str, int countLen, char c) {
        if (str.length() > countLen) {
            return str;
        }
        char[] chs = new char[countLen];
        Arrays.fill(chs, c);
        char[] src = str.toCharArray();
        System.arraycopy(src, 0, chs, countLen - src.length, src.length);
        return new String(chs);
    }
    public static void main(String[] args) throws Exception {
        new FileUtils().mergePartFiles("D:\test\frj\", ".mp4", "D:\test\frj\merge.mp4"); //1,626,409,091
    }
    /***
     * 构建文件大小集合
     *
     * @param len
     * @param count
     * @param arr
     */
    public static void testLen(Integer len, int count, List<Integer> arr) {
        int i = len / count;
        int j = 0;
        if (len % count == 0) {
            while (j < count) {
                arr.add(i);
                j++;
            }
        } else {
            int sum = 0;
            while (j < count - 1) {
                sum += i;
                arr.add(i);
                j++;
            }
            arr.add(len - sum);
        }
        System.out.println(arr);
    }
    /**
     * 根据文件名称 比较文件
     */
    private class FileComparator implements Comparator<File> {
        
        public int compare(File o1, File o2) {
            return o1.getName().compareToIgnoreCase(o2.getName());
        }
    }
}

public class SplitRunnable implements Runnable {
    int byteSize;
    String partFileName;
    File originFile;
    int startPos;
    Socket socket;
    public SplitRunnable(int byteSize, int startPos,String partFileName,File originFile) throws IOException {
        this.startPos = startPos;
        this.byteSize = byteSize;
        this.partFileName = partFileName;
        this.originFile = originFile;
//        socket = new Socket("localhost",8088);
    }
    
    public void run() {
        RandomAccessFile rfile;
        OutputStream os;
//        DataOutputStream dos;
        try {
//            dos = new DataOutputStream(socket.getOutputStream());
            rfile = new RandomAccessFile(originFile,"r");
            byte[] b = new byte[byteSize];
            rfile.seek(startPos);
            int s = rfile.read(b);
            File file = new File(partFileName);
//            写到本地的时候用
            os = new FileOutputStream("d:/test/frj/" + partFileName);
//            dos.writeUTF(file.getName());
//            dos.flush();
//            dos.writeLong(file.length());
//            dos.flush();
//            dos.write(b,0,s);
//            dos.flush();
//            dos.close();
            os.write(b,0,s);
            os.flush();
            os.close();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

public class MergeRunnable implements Runnable {
    long startPos;
    String mergeFileName;
    File partFile;
    public MergeRunnable(int startPos, String mergeFileName, File partFile) {
        this.startPos = startPos;
        this.mergeFileName = mergeFileName;
        this.partFile = partFile;
    }
    
    public void run() {
        RandomAccessFile rfile;
        try {
            rfile = new RandomAccessFile(mergeFileName,"rw");
            rfile.seek(startPos);
            FileInputStream fs = new FileInputStream(partFile);
            byte[] b = new byte[fs.available()];
            fs.read(b);
            fs.close();
            rfile.write(b);
            rfile.close();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}