【方法總結】建立、讀取、刪除文件相關操做

時間 2019-12-07

標籤方法總結建立讀取刪除文件相關简体版

原文原文鏈接

總結一波文件操做相關的共通方法（拿來就用）android

須要申請的權限：app

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

1.獲取文件夾下的全部文件名ide

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卡上建立文件ui

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卡上建立文件夾google

public static File createFolder(String fileName) throws IOException {
    File file = new File(fileName);
    if (!isFileExists(file)) {
        file.mkdirs();
    }
    return file;
}

4.讀取SD卡中文本文件spa

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.刪除單個文件code

public static boolean deleteFile(String filePath) {
    File file = new File(filePath);
    if (file.isFile() && file.exists()) {
        return file.delete();
    }
    return false;
}

filePath 被刪除文件的文件名blog

return 文件刪除成功返回true，不然返回false。rem

6.刪除文件夾以及其目錄下的文件get

public static boolean deleteFolder(String filePath) {
    boolean flag = false;
    // 若是filePath不以文件分隔符結尾，自動添加文件分隔符
    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();
    // 遍歷刪除文件夾下的全部文件(包括子目錄)
    for (File file : files) {
        if (file.isFile()) {
            // 刪除子文件
            flag = deleteFile(file.getAbsolutePath());
            if (!flag)
                break;
        } else {
            // 刪除子目錄
            flag = deleteFolder(file.getAbsolutePath());
            if (!flag)
                break;
        }
    }
    if (!flag)
        return false;
    // 刪除當前空目錄
    return dirFile.delete();
}

filePath 被刪除目錄的文件路徑
return 目錄刪除成功返回true，不然返回false

7.把文件轉換成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.根據相冊媒體庫路徑轉換成SD卡路徑(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;
}

上面方法可能須要下列輔助方法的支持：

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;
}