从网络地址下载文件

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;

public class HttpUtils {

    
    public static void downLoadFromUrl(String urlStr, String fileName, String savePath) throws IOException {
        URL url = new URL(urlStr);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        //设置超时间为3秒
        conn.setConnectTimeout(30 * 1000);
        conn.setReadTimeout(60 * 1000);
        //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();
        }
    }


    
    public void downloadExcelByUrl(String url, String fileName, HttpServletResponse response) throws Exception {
        fileName = URLEncoder.encode(fileName, "UTF-8");
        response.setContentType("application/vnd.ms-excel;charset=utf-8");
        response.setHeader("Content-Disposition", "attachment; filename=" + fileName + ".xlsx");
        byte[] buff = new byte[1024];
        BufferedInputStream bis = null;
        OutputStream outputStream = null;
        InputStream inputStream = null;
        try {
            URL httpUrl = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) httpUrl.openConnection();
            connection.setConnectTimeout(3000);
            connection.setReadTimeout(5000);
            outputStream = response.getOutputStream();
            inputStream = connection.getInputStream();
            bis = new BufferedInputStream(inputStream);
            int len;
            while ((len = bis.read(buff)) > 0) {
                outputStream.write(buff, 0, len);
                outputStream.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (bis != null) {
                bis.close();
            }
            if (outputStream != null) {
                outputStream.close();
            }
            if (inputStream != null) {
                inputStream.close();
            }
        }
    }

 
    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();
    }
}