Java從網絡的url下載文件

 

工具類的代碼如下:

---

package utils;

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

public class HttpRequest {
    /**
     * 從網絡Url中下載文件
     * @param urlStr
     * @param fileName
     * @param savePath
     * @throws IOException
     */
    public static File downLoadFromUrl(String urlStr,String fileName,String savePath) {
        InputStream inputStream = null;
        FileOutputStream fos = null;
        try {
            URL url = new URL(urlStr);
            HttpURLConnection conn = (HttpURLConnection)url.openConnection();
            //設置超時間爲3秒
            conn.setConnectTimeout(3*1000);
            //防止屏蔽程序抓取而返回403錯誤
            conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
            /* conn.setRequestProperty("lfwywxqyh_token",toekn);*/
            //得到輸入流
            inputStream = conn.getInputStream();
            //獲取自己數組
            byte[] getData = readInputStream(inputStream);

            //文件保存位置
            File saveDir = new File(savePath);
            //如果不存在目錄，則創建
            if(!saveDir.exists()){
                saveDir.mkdir();
            }
            //路徑+分隔符+文件名
            File file = new File(saveDir + File.separator + fileName);
            fos = new FileOutputStream(file);
            fos.write(getData);
            System.out.println("下載文件成功");
            return file;
        }catch (Exception e){
            return null;
        }finally {
            //必須關流
            if(fos != null){
                try {
                    fos.close();
                }catch (Exception e){
                    System.out.println("fos關流失敗");
                }
            }
            if(inputStream != null){
                try {
                    inputStream.close();
                }catch (Exception e){
                    System.out.println("inputStream關流失敗");
                }
            }
        }

    }



    /**
     * 從輸入流中獲取字節數組
     * @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();
    }
    


}