筆者將 Android 12 外部存儲空間（External Storage）的路徑放入程式內作測試，外部存儲空間路徑也是蠻多，所以將資料匯集紀錄，因為很多時候需要讀寫本地檔的操作，將來作參考作用。這個程式是使用了 SAF（Storage Access Framework）框架，暫時解決了 Android 12 外部存儲空間讀寫檔案程式問題。
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| Android 12 外部存儲空間讀寫程式 |
開發環境：Android Studio 4.0.1 版本
最低 SDK 版本：minSdkVersion 24
測試手機：Samsung Galaxy M33 5G
測試手機系統版本：Android 12（Snow Cone / 2021）
原程式：C:\Development\Development_Android\DIY-Android-190-15d Android12ReadWriteFile bugworkshop 20230304 - ReadWriteFileExt
程式：C:\Development\Development_Android\Android_Project\DIY-Android-190-15d Android12ReadWriteFile bugworkshop 20230304 - ReadWriteFileExt
MainActivity.java：
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@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_readwrite_ext);
mbtn_save = (Button)findViewById(R.id.btn_save); mbtn_load = (Button)findViewById(R.id.btn_load); mtxt_filepath = (TextView) findViewById(R.id.text_path); mtxt_filecontent= (TextView) findViewById(R.id.text_content); mtxt_filecontent.setMovementMethod(new ScrollingMovementMethod()); mlist_file = findViewById(R.id.list_file); medit_input = (EditText) findViewById(R.id.edittext_input);
myfolder= getFilesDir(); myFilename = new File(getFilesDir(), filename);
mbtn_save.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { filePicker(false); } });
mbtn_load.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { read(); } }); }
ActivityResultLauncher<Intent> mLaunchFilePicker = registerForActivityResult( new ActivityResultContracts.StartActivityForResult(), result -> { Intent data = result.getData(); if (result.getResultCode() == Activity.RESULT_OK && data != null) { handleFileResult(data,true); } });
ActivityResultLauncher<Intent> mLaunchFileSaver = registerForActivityResult( new ActivityResultContracts.StartActivityForResult(), result -> { Intent data = result.getData(); if (result.getResultCode() == Activity.RESULT_OK && data != null) { handleFileResult(data,false); } });
void filePicker(boolean readOrWrite) { if (readOrWrite) { intent = new Intent(Intent.ACTION_OPEN_DOCUMENT); intent.setType("*/*"); intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION); intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true); mLaunchFilePicker.launch(intent); } else { intent = new Intent(Intent.ACTION_CREATE_DOCUMENT); intent.setType("text/*"); intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION); intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true); mLaunchFileSaver.launch(intent);
} }
private void handleFileResult(Intent data, boolean readOrWrite) { mFileUri = data.getData();
if (mFileUri != null) { try { getContentResolver().takePersistableUriPermission(mFileUri, Intent.FLAG_GRANT_READ_URI_PERMISSION); } catch (SecurityException e) { e.printStackTrace(); } if (readOrWrite) { read(); } else { write(); } } } |
MainActivity.java - Read External Storage File：
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void read() {
try { InputStreamReader inputStreamReader = new InputStreamReader(getContentResolver().openInputStream(mFileUri)); BufferedReader reader = new BufferedReader(inputStreamReader); StringBuilder builder = new StringBuilder(); try { String fileContentLine; while ((fileContentLine = reader.readLine()) != null) { fileContentLine += "\n"; builder.append(fileContentLine); } String fileContent = builder.toString(); mtxt_filecontent.setText(fileContent); medit_input.setText(fileContent); } finally { mtxt_filepath.setText(mFileUri.toString()); reader.close(); inputStreamReader.close(); } } catch (IOException e) { e.printStackTrace(); } } |
MainActivity.java - Write External Storage File：
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void write() { mtxt_filepath.setText("Save File=" + mFileUri.toString());
try { OutputStreamWriter outputStreamWriter = new OutputStreamWriter(getContentResolver().openOutputStream(mFileUri)); BufferedWriter writer = new BufferedWriter(outputStreamWriter); String textContent = medit_input.getText().toString();
try { writer.write(textContent); } finally { writer.close(); outputStreamWriter.close(); } } catch (IOException e) { e.printStackTrace(); } } |
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| Android 12 外部存儲空間寫入程式 |
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| Android 12 外部存儲空間寫入程式 |
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| Android 12 外部存儲空間讀取程式 |
