android连接服务器下载文件工具类

public static File downLoad(String serverPath,String savedPath,ProgressDialog dialog){try {URL url=new URL(serverPath);HttpURLConnection _conn=(HttpURLConnection) url.openConnection();_conn.setRequestMethod("GET");_conn.setConnectTimeout(5000);int code=_conn.getResponseCode();if(code==200){//设置进度条的长度dialog.setMax(_conn.getContentLength());InputStream is=_conn.getInputStream();File _file=new File(savedPath);FileOutputStream _FileOutputStream=new FileOutputStream(_file);int len=0;byte[] buffer= new byte[1024];int _total=0;while((len=is.read(buffer))!=-1){_FileOutputStream.write(buffer, 0,len);_total+=len;dialog.setProgress(_total);Thread.sleep(20);}_FileOutputStream.flush();_FileOutputStream.close();is.close();return _file;}else {return null;}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();return null;}}