java 断点续传文件到远程服务器

package com.my.file;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.text.SimpleDateFormat;
import java.util.Date;

public class FileUploadTask {

    public static void main(String[] args) {
        String fromPath = "d://target.avi";
        String tmpPath = "e://temp//";
        FileUploadTask fileTask = new FileUploadTask();
        long s = System.currentTimeMillis();
        fileTask.uploadFileByPoint(fromPath, tmpPath);
        long e = System.currentTimeMillis();
        System.out.println("all cost time :" + (e - s) + " ms");
    }

    /**
     * upload file by point
     * @param targetPath
     * @param uploadPath
     */
    public void uploadFileByPoint(String targetPath, String uploadPath) {
        File targetFile = new File(targetPath);
        String fileName = targetFile.getName();
        int nlastPoint = fileName.lastIndexOf(".");
        String prefix = fileName.substring(0, nlastPoint);
        String suffix = fileName.substring(nlastPoint);
        File uploadFile = new File(uploadPath + fileName);
        File tmpFile = new File(uploadPath + prefix + ".dat");
        // if upload file exist,rename upload file
        if (uploadFile.exists()) {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh.mm.ss");
            Date date = new Date();
            uploadFile.renameTo(new File(uploadPath + prefix + "_["
                    + sdf.format(date) + "]" + suffix));
        }
        long lfBytes = targetFile.length();
        long ltmpfBytes = tmpFile.length();
        System.out.println("target file size:" + lfBytes + " bytes");
        System.out.println("temp file size:" + ltmpfBytes + " bytes");
        FileInputStream fileIn = null;
        BufferedInputStream bufIn = null;
        RandomAccessFile randomFile = null;
        try {
            fileIn = new FileInputStream(targetFile);
            bufIn = new BufferedInputStream(fileIn);
            randomFile = new RandomAccessFile(tmpFile, "rw");
            // skip the temp file bytes
            bufIn.skip(ltmpfBytes);
            // offset file point bytes
            randomFile.seek(ltmpfBytes);
            byte[] bytes = new byte[1024];
            while (bufIn.read(bytes) != -1) {
                randomFile.write(bytes);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // release memory to free
            releaseMemory(fileIn, bufIn, randomFile);
            // upload file over,remark file size
            ltmpfBytes = tmpFile.length();
            System.out
                    .println("upload file over size:" + ltmpfBytes + " bytes");
            // if upload over,rename the temp file
            if (ltmpfBytes >= lfBytes) {
                tmpFile.renameTo(new File(uploadPath + fileName));
            }
        }
    }

    /**
     *  release memory to free
     * @param fileIn
     * @param bufIn
     * @param randomFile
     */
    private void releaseMemory(FileInputStream fileIn,
            BufferedInputStream bufIn, RandomAccessFile randomFile) {
        if (fileIn != null) {
            try {
                fileIn.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (bufIn != null) {
            try {
                bufIn.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (randomFile != null) {
            try {
                randomFile.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}