android学习笔记3-文件下载

/** * 根据URL下载文件，前提是这个文件当中的内容是文本，函数的返回值就是文件当中的内容 * 1.创建一个URL对象 * 2.通过URL对象，创建一个HttpURLConnection对象 * 3.得到InputStram * 4.从InputStream当中读取数据 * @param urlStr * @return */ //下载文本文件public String download(String urlStr) {StringBuffer sb = new StringBuffer();String line = null;BufferedReader buffer = null;try {// 创建一个URL对象url = new URL(urlStr);// 创建一个Http连接HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();// 使用IO流读取数据buffer = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));while ((line = buffer.readLine()) != null) {sb.append(line);}} catch (Exception e) {e.printStackTrace();} finally {try {buffer.close();} catch (Exception e) {e.printStackTrace();}}return sb.toString();}SDPATH = Environment.getExternalStorageDirectory() + "/";            //获取设备的SD卡的路径名//下载其他类型文件public int downFile(String urlStr, String path, String fileName) {InputStream inputStream = null;try {FileUtils fileUtils = new FileUtils();if (fileUtils.isFileExist(path + fileName)) {return 1;} else {inputStream = getInputStreamFromUrl(urlStr);File resultFile = fileUtils.write2SDFromInput(path,fileName, inputStream);if (resultFile == null) {return -1;}}} catch (Exception e) {e.printStackTrace();return -1;} finally {try {inputStream.close();} catch (Exception e) {e.printStackTrace();}}return 0;}public InputStream getInputStreamFromUrl(String urlStr)throws MalformedURLException, IOException {url = new URL(urlStr);HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();InputStream inputStream = urlConn.getInputStream();return inputStream;}public File write2SDFromInput(String path,String fileName,InputStream input){File file = null;OutputStream output = null;try{creatSDDir(path);file = creatSDFile(path + fileName);output = new FileOutputStream(file);byte buffer [] = new byte[4 * 1024];while((input.read(buffer)) != -1){output.write(buffer);}output.flush();}catch(Exception e){e.printStackTrace();}finally{try{output.close();}catch(Exception e){e.printStackTrace();}}return file;}