Android读写文件工具类详解

 public class Utils { private static String path1 = Environment.getExternalStorageDirectory().getAbsolutePath(); private static String path2 = Environment.getDownloadCacheDirectory().getAbsolutePath(); private static String pathExt = "/111/222/333/444/555/"; private static String fileName = "6.txt"; public static void write(String str) { String filePath = null; boolean hasSDCard =Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED); if (hasSDCard) { filePath = path1 + pathExt + fileName; } else { filePath = path2 + pathExt + fileName; } try { File file = new File(filePath); if (!file.exists()) { //mkdirs()方法生成多层文件夹 //mkdir()方法生成一层层文件夹 //        File dir = new File(file.getParent()); //        dir.mkdirs(); file.getParentFile().mkdirs();//生成文件外层的文件夹 file.createNewFile();//生成文件 } FileOutputStream os = new FileOutputStream(file); os.write(str.getBytes()); os.close(); } catch (Exception e) { e.printStackTrace(); } } public static String read() { String content = ""; String filePath; boolean sdcard = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED); if (sdcard) { filePath = path1 + pathExt + fileName; } else { filePath = path2 + pathExt + fileName; } try { File file = new File(filePath); if (file.exists()) { FileInputStream is = new FileInputStream(file); InputStreamReader inputReader = new InputStreamReader(is);//设置流读取方式 BufferedReader buffReader = new BufferedReader(inputReader); String line; try { while (null != (line = buffReader.readLine())) { content += line + "\n";//读取的文件容 } is.close();//关闭输入流 } catch (IOException e) { e.printStackTrace(); } finally { try { if (null != is) { is.close(); } } catch (IOException e) { e.printStackTrace(); } } } } catch (FileNotFoundException e) { e.printStackTrace(); } return content; } }

 ArrayList permissionList = new ArrayList<>(); private String[] permissions = { "android.permission.READ_EXTERNAL_STORAGE", "android.permission.WRITE_EXTERNAL_STORAGE" }; //检测是否有写的权限 //判断手机版本,如果低于6.0 则不用申请权限,直接拍照 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { if (checkSelfPermission(permissions[0]) != PackageManager.PERMISSION_GRANTED) { permissionList.add(permissions[0]); } if (checkSelfPermission(permissions[1]) != PackageManager.PERMISSION_GRANTED) { permissionList.add(permissions[1]); } if (!permissionList.isEmpty()) { String[] permissions1 = permissionList.toArray(new String[permissionList.size()]); requestPermissions(permissions1, 1); } else { Utils.write("balabala"); Utils.read(); } } else { Utils.write("balabala"); Utils.read(); } @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { switch (requestCode){ case 1: if (PackageManager.PERMISSION_GRANTED == grantResults[0]){ Utils.write("balabala"); Utils.read(); } else { Log.d(TAG, "fail: "); } break; } }