Android Studio - Android 12 外部存儲空間讀寫檔案程式（一百一十）

Android Studio - Android 12 外部存儲空間讀寫檔案程式（一百一十）：

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。

Android 12 外部存儲空間讀寫程式

操作系統：Windows 7 64-bit 版本
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：

@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：

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：

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();         }     }

Android 12 外部存儲空間寫入程式

Android 12 外部存儲空間寫入程式

Android 12 外部存儲空間讀取程式