java 零拷贝(zero copy)

        package com.weidou.mota.output;      
        import java.io.File;
        import java.io.FileInputStream;
        import java.io.FileNotFoundException;
        import java.io.FileOutputStream;
        import java.io.IOException;
        import java.nio.channels.FileChannel;
        import java.util.ArrayList;
        import java.util.HashSet;
        import java.util.List;
        import java.util.Set;
        import java.util.concurrent.BlockingQueue;
        import java.util.concurrent.LinkedBlockingDeque;
        public class FileSuper {
    
        public static final long KB = 1024l;
        public static final long MB = 1024 * KB;
        public static final long GB = 1024 * MB;
        private FileSuper() {   
        }
        public static Set<File> folderWalk(String path) {
            File folder = new File(path);
            Set<File> fileList = new HashSet<File>();
            for (File file : folder.listFiles()) {
                if (file.isDirectory()) {
                    fileList.addAll(folderWalk(file.getAbsolutePath()));
                } else {
                    fileList.add(file);
                }
            }
            return fileList;
        }
        public static boolean spiltFilesBySize(BlockingQueue<File> fileQueue,
            final long dataSize, File outPutDir, final String fileSuffix,
            final String filePrex) throws IOException {
            if (!(outPutDir.isDirectory() && outPutDir.exists())) {
                throw new IllegalArgumentException("不存在路径 或者路径不是文件夹 :"
                        + outPutDir.getAbsolutePath());
            }
            
            long remainSize = 0;// 要生成的文件还有剩余大小
            int outFileSeq = 1; //输出文件序号
            long fileInSize = 0; //输入文件大小
            long fileInRemainSize = 0; //文件剩下的大小
            FileChannel outFile = null; //文件输出nio
            FileChannel fileIn = null; //文件输入nio
            while (!fileQueue.isEmpty()) { //看是否还有文件
                    if (fileInRemainSize <= 0) {//如果输入文件已经全部存入
                        if (fileIn != null) { //判断文件是否为空
                            fileIn.close(); //关闭输入文件
                            fileIn = null; //输入文件为null
                    }
                    File filePoll = fileQueue.poll(); //取得一个输入文件
                    fileIn = getInfile(filePoll); //获得读入文件nio
                    fileInRemainSize = fileIn.size(); // 文件的指针 = fileInSize -
                                                    // fileInRemainSize
                    fileInSize = fileIn.size(); //记录文件大小
                    }
                    if (remainSize <= 0) { //距离一个生成的文件还有多少
                        if (outFile != null) { //输出文件不为空
                            outFile.close(); //输入文件关闭
                        }
                        outFile = getOutFile(outPutDir, fileSuffix, filePrex,
                        outFileSeq); //生成一个文件输出nio
                        outFileSeq = outFileSeq + 1; //序列号 + 1
                        remainSize = dataSize; //重置文件输出大小
                    }
                    long cutFileInPoint = 0l; //文件结构 [已经输出大小 + fileInRemainSize ] <=fileInSize
                    if (fileInRemainSize > remainSize) { 
                        cutFileInPoint = remainSize;
                        remainSize = 0;
                    } else if (fileInRemainSize <= remainSize) {
                        cutFileInPoint = fileInRemainSize;
                        remainSize = remainSize - cutFileInPoint;
                    }
                    //这块是重点 nio 不支持大于4g数据的复制，所以一块块复制(切片复制)
                    for (long count = 0; count <= cutFileInPoint; count = count
                    + 70 * MB) { //这里粗犷的处理 , 因为文件数据很多丢失 《 70 mb 不算什么
                        fileIn.transferTo(fileInSize - fileInRemainSize + count,
                        70 * MB, outFile); //复制
                    }
                    fileInRemainSize = fileInRemainSize - cutFileInPoint; //
            }
            return true;
        }
        @SuppressWarnings("resource")
        public static FileChannel getInfile(File file) throws FileNotFoundException {
            return new FileInputStream(file).getChannel();
        }
        @SuppressWarnings("resource")
        public static FileChannel getOutFile(File outPutDir,
                final String fileSuffix, final String filePrex, int outFileSeq)
                throws FileNotFoundException {
            return new FileOutputStream(new File(outPutDir.getAbsolutePath() + "/"
                + fileSuffix + outFileSeq + filePrex)).getChannel();
        }
        public static void main(String args []) throws IOException
        {
            if (args.length < 4) {
                throw new IllegalArgumentException("参数太少");
            }
            List<String> inputPaths = new ArrayList<String>();
            String prex = "NO_";
            String suffix = ".csv";
            long size = FileSplit.GB * 50;
            File output = null;
            for (int i = 0; i < args.length; i++) {
                String choice = args[i];
                if (choice.equals("--filelist")) {
                    for (String path : args[i + 1].split("#")) {
                        inputPaths.add(path.trim());
                    }
                    i = i + 1;
                } else if (choice.equals("--prex")) {
                    prex = args[i + 1];
                    i = i + 1;
                } else if (choice.equals("--suffix")) {
                    suffix = args[i + 1];
                    i = i + 1;
                } else if (choice.equals("--output")) {
                    output = new File(args[i + 1]);
                    i = i + 1;
                } else if (choice.equals("--filegb")) { 
                }
            }
            if (StringUtils.isEmpty(prex) || StringUtils.isEmpty(suffix)
                    || inputPaths.size() <= 0 || output == null) {
                throw new IllegalArgumentException("输入参数有误!");
            }
            BlockingQueue<File> fileQueue = new LinkedBlockingDeque<File>();
            for (String path : inputPaths) {
                fileQueue.addAll(folderWalk(path));
            }
            spiltFilesBySize(fileQueue, size, output, prex, suffix);
        }
    }