逐行讀取文件

Question

我正在創建一個 Android 應用程序來跟蹤財務費用，我希望允許用戶將財務交易批量導入我的應用程序。 交易將以 .csv/.txt 文件的形式出現。

但是，我收到了一個神秘的異常：

 java.lang.AbstractMethodError: abstract method "android.content.IContentProvider android.content.ContentResolver.acquireUnstableProvider(android.content.Context, java.lang.String)" at android.content.ContentResolver.acquireUnstableProvider(ContentResolver.java:1780) at android.content.ContentResolver.openTypedAssetFileDescriptor(ContentResolver.java:1394) at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:1247) at android.content.ContentResolver.openInputStream(ContentResolver.java:967) ....

工作流程如下：用戶選擇要導入的文本文件，App 導入內容。

啟動文件選擇器：

Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.setType("*/*");
//intent.addCategory("CATEGORY_OPENABLE");

startActivityForResult(intent, REEQUEST_CODE_IMPORT);

捕捉結果：

public void onActivityResult(int requestCode, int resultCode, Intent data) {
        // Check which request we're responding to
        if (requestCode == REEQUEST_CODE_IMPORT) {
            // Make sure the request was successful
            Uri path = data.getData();

            if (resultCode == RESULT_OK && path != null) {
                InputStream inputStream = null;
                try {
                    ContentResolver contentResolver = new ContentResolver(getContext()) {};

                    // Error happens in the next line
                    inputStream = contentResolver.openInputStream(path);

                    // Get the object of DataInputStream
                    DataInputStream in = new DataInputStream(inputStream);
                    BufferedReader br = new BufferedReader(new InputStreamReader(in));
                    String line = "";

                    while((line = br.readLine()) != null) {
                        // Do something meaningful... 
                    }

                } catch () {
                    // Catch the exceptions ( I have removed some boiler plate code here...)
                } finally {
                    // Close the path ( I have removed some boiler plate code here...) 
                        inputStream.close();
                    }
                }
            }
        }

Answer 1

Android 文檔幫我解決了這個問題： Access documents and other files from shared storage - Input Stream

以下代碼改編正在工作：

public void onActivityResult(int requestCode, int resultCode, Intent data) {
        // Check which request we're responding to
        if (requestCode == REEQUEST_CODE_IMPORT) {
            // Make sure the request was successful
            Uri path = data.getData();

            if (resultCode == RESULT_OK && path != null) {
                    StringBuilder stringBuilder = new StringBuilder();
                    try (InputStream inputStream = getActivity().getContentResolver().openInputStream(path);
                         BufferedReader reader = new BufferedReader(
                                 new InputStreamReader(Objects.requireNonNull(inputStream)))) {
                        String line;
                        while ((line = reader.readLine()) != null) {
                            Log.d(TAG, line);
                            stringBuilder.append(line);
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    String content = stringBuilder.toString();
                    // Do something with it
            }
        }
    }