【方法总结】创建、读取、删除文件相关操作
总结一波文件操作相关的共通方法（拿来就用）
需要申请的权限：
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
1.获取文件夹下的所有文件名
public static List<String> getFileName(String fileName) { List<String> fileList = new ArrayList<>(); File file = new File(fileName); if (!file.exists()) { return null; } File f[] = file.listFiles(); for (int i = 0; i < f.length; i++) { File fs = f[i]; if (!fs.isDirectory()) { fileList.add(fs.getName()); } } return fileList; }
2.在SD卡上创建文件
public static File createFile(String fileName) throws IOException { File file = new File(fileName); if (!isFileExists(file)) { if (file.isDirectory()) { file.mkdirs(); } else { file.createNewFile(); } } return file; }
3.在SD卡上创建文件夹
public static File createFolder(String fileName) throws IOException { File file = new File(fileName); if (!isFileExists(file)) { file.mkdirs(); } return file; }
4.读取SD卡中文本文件
public synchronized static String readFile(String fileName) { StringBuffer sb = new StringBuffer(); File file = new File(fileName); String str = null; try { InputStream is = new FileInputStream(file); InputStreamReader isr = new InputStreamReader(is, "UTF-8"); @SuppressWarnings("resource") BufferedReader reader = new BufferedReader(isr); while ((str = reader.readLine()) != null) { sb.append(str); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return sb.toString(); }
5.删除单个文件
public static boolean deleteFile(String filePath) { File file = new File(filePath); if (file.isFile() && file.exists()) { return file.delete(); } return false; }
filePath 被删除文件的文件名
return 文件删除成功返回true，否则返回false。
6.删除文件夹以及其目录下的文件
public static boolean deleteFolder(String filePath) { boolean flag = false; // 如果filePath不以文件分隔符结尾，自动添加文件分隔符 if (!filePath.endsWith(File.separator)) { filePath = filePath + File.separator; } File dirFile = new File(filePath); if (!dirFile.exists() || !dirFile.isDirectory()) { return false; } flag = true; File[] files = dirFile.listFiles(); // 遍历删除文件夹下的所有文件(包括子目录) for (File file : files) { if (file.isFile()) { // 删除子文件 flag = deleteFile(file.getAbsolutePath()); if (!flag) break; } else { // 删除子目录 flag = deleteFolder(file.getAbsolutePath()); if (!flag) break; } } if (!flag) return false; // 删除当前空目录 return dirFile.delete(); }
filePath 被删除目录的文件路径
return 目录删除成功返回true，否则返回false
7.把文件转换成Base64
public static String encodeBase64File(String path) throws Exception { byte[] videoBytes; ByteArrayOutputStream baos = new ByteArrayOutputStream(); @SuppressWarnings("resource") FileInputStream fis = new FileInputStream(new File(path)); byte[] buf = new byte[1024]; int n; while (-1 != (n = fis.read(buf))) { baos.write(buf, 0, n); } videoBytes = baos.toByteArray(); return Base64.encodeToString(videoBytes, Base64.NO_WRAP); }
8.根据相册媒体库路径转换成SD卡路径(Android 4.4以上)
@TargetApi(Build.VERSION_CODES.KITKAT) public static String getPath(final Context context, final Uri uri) { final boolean isOverKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT; // DocumentProvider if (isOverKitKat && DocumentsContract.isDocumentUri(context, uri)) { // ExternalStorageProvider if (isExternalStorageDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; if ("primary".equalsIgnoreCase(type)) { return Environment.getExternalStorageDirectory() + "/" + split[1]; } } // DownloadsProvider else if (isDownloadsDocument(uri)) { final String id = DocumentsContract.getDocumentId(uri); final Uri contentUri = ContentUris.withAppendedId( Uri.parse("content://downloads/public_downloads"), Long.valueOf(id)); return getDataColumn(context, contentUri, null, null); } // MediaProvider else if (isMediaDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; Uri contentUri = null; if ("image".equals(type)) { contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI; } else if ("video".equals(type)) { contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI; } else if ("audio".equals(type)) { contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; } final String selection = "_id=?"; final String[] selectionArgs = new String[]{split[1]}; return getDataColumn(context, contentUri, selection, selectionArgs); } } // MediaStore (and general) else if ("content".equalsIgnoreCase(uri.getScheme())) { // Return the remote address if (isGooglePhotosUri(uri)) return uri.getLastPathSegment(); return getDataColumn(context, uri, null, null); } // File else if ("file".equalsIgnoreCase(uri.getScheme())) { return uri.getPath(); } return null; }
上面方法可能需要下列辅助方法的支持：
public static boolean isFileExists(File file) { return file.exists(); }
public static boolean isExternalStorageDocument(Uri uri) { return "com.android.externalstorage.documents".equals(uri.getAuthority()); }
public static boolean isDownloadsDocument(Uri uri) { return "com.android.providers.downloads.documents".equals(uri.getAuthority()); }
public static boolean isMediaDocument(Uri uri) { return "com.android.providers.media.documents".equals(uri.getAuthority()); }
public static boolean isGooglePhotosUri(Uri uri) { return "com.google.android.apps.photos.content".equals(uri.getAuthority()); }
@SuppressLint("NewApi")
public static String getDataColumn(Context context, Uri uri,
String selection, String[] selectionArgs) {
Cursor cursor = null;
final String column = "_data";
final String[] projection = {column};
try {
cursor = context.getContentResolver().query(uri, projection,
selection, selectionArgs, null);
if (cursor != null && cursor.moveToFirst()) {
final int index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(index);
}
} finally {
if (cursor != null)
cursor.close();
}
return null;
}
长期更新，未完待续。。。
