java实现在线文件下载

一个比较cao  dan的需求，有个人本来应该给我一套模板，然后我做一个上传，结果他给我了我一堆以前服务器上的文档地址，所以我就需要从A类型服务器上，先把文档下载下来，然后转存到B类型服务器上。

package com.example.demo.utils;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class DownFile {

    public static String downLoadFromUrl(String urlStr, String fileName, String savePath) {
        try {

            URL url = new URL(urlStr);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            // 设置超时间为3秒
            conn.setConnectTimeout(3 * 1000);
            // 防止屏蔽程序抓取而返回403错误
            conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");

            // 得到输入流
            InputStream inputStream = conn.getInputStream();
            // 获取自己数组
            byte[] getData = readInputStream(inputStream);

            // 文件保存位置
            File saveDir = new File(savePath);
            if (!saveDir.exists()) {
                saveDir.mkdir();
            }
            File file = new File(saveDir + File.separator + fileName);
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(getData);
            if (fos != null) {
                fos.close();
            }
            if (inputStream != null) {
                inputStream.close();
            }
            // System.out.println("info:"+url+" download success");
            return saveDir + File.separator + fileName;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";

    }

    /**
     * 从输入流中获取字节数组
     *
     * @param inputStream
     * @return
     * @throws IOException
     */
    public static byte[] readInputStream(InputStream inputStream) throws IOException {
        byte[] buffer = new byte[1024];
        int len = 0;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while ((len = inputStream.read(buffer)) != -1) {
            bos.write(buffer, 0, len);
        }
        bos.close();
        return bos.toByteArray();
    }

    public static void main(String[] args){
        String url = "http://www.jujiaoedu.com/files/hash/7jw/7jw4f6kfbk0xvn7mmtq2vud.docx";
        String[] items = url.split("\\.");
        String fileType = items[items.length-1];
        String path = DownFile.downLoadFromUrl(url,"temp."+fileType,"C:\\Users\\dell\\Desktop\\files");//
        System.out.println(path);
    }