java 根据url 下载文件

public static void downLoadByUrl(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(5*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");

}

/**

* 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();

}