【发布时间】：2014-06-12 15:14:00
【问题描述】：
我有一个将数据保存到名为“sensorLog.txt”的文件的应用程序。我不确定它到底存储在哪里，但我知道它只能由应用程序访问并且它在内部存储器中。
当我单击“导出”按钮时，我希望能够将当前文件的副本写入外部存储。我已经粘贴了一小部分程序，但我不确定如何将 sensorLog.txt 文件复制到外部存储。
public class MainActivity extends Activity {
private static final String DEBUG_TAG = "MainActivity";
private Button buttonStartService;
private Button buttonStopService;
private Button buttonSettings;
private Button buttonExport;
private TextView textStatus;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Context context = getApplicationContext();
setContentView(R.layout.activity_main);
buttonStartService = (Button) findViewById(R.id.button_start_service);
buttonStopService = (Button) findViewById(R.id.button_stop_service);
buttonSettings = (Button) findViewById(R.id.button_settings);
buttonExport = (Button) findViewById(R.id.button_export);
textStatus = (TextView) findViewById(R.id.text_status);
buttonStartService.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
startSensorService();
}
});
buttonStopService.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
stopSensorService();
}
});
//export button listener
buttonExport.setOnClickListener(export_handler);
}
public void startSensorService() {
// Schedule
AlarmManager scheduler = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(getApplicationContext(), SensorService.class);
PendingIntent scheduledIntent = PendingIntent.getService(getApplicationContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
// 30 seconds
long interval = 30 * 1000;
scheduler.setInexactRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), interval, scheduledIntent);
Log.d(DEBUG_TAG, "Service started");
}
public void stopSensorService() {
// Cancel
AlarmManager scheduler = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(this, SensorService.class);
PendingIntent scheduledIntent = PendingIntent.getService(getApplicationContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
scheduler.cancel(scheduledIntent);
Log.d(DEBUG_TAG, "Service stopped");
}
View.OnClickListener export_handler = new View.OnClickListener() {
public void onClick(View v)
{
// Here is the part I am not sure what to do. I want to copy a file sensorLog.txt that has all my sensor information to sd card
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state))
{
Log.d(DEBUG_TAG, "SD card detected");
stopSensorService();
File file = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOCUMENTS),"SensorLog.txt");
// delete file from the internal storage once exported
context.deleteFile("SensorLog.txt");
startSensorService();
}
else
{
Log.d(DEBUG_TAG, "No external storage detected(cannot copy file)");
}
}
};
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
我创建 sensorLog.txt 的部分***（我认为没有必要阅读这个问题，但以防万一有人需要）*：
private class SensorServiceLoggerTask extends AsyncTask<SensorFrame, Void, Void> {
@Override
protected Void doInBackground(SensorFrame... frames) {
SensorFrame frame = frames[0];
BufferedWriter bufWr = null;
try {
File file = new File(getApplicationContext().getFilesDir(), "SensorLog.txt");
if (file.exists()) {
// Write to new file
bufWr = new BufferedWriter(new FileWriter(file, true));
} else {
file.createNewFile();
Log.d(DEBUG_TAG, "New log file created");
// Append to existing file
bufWr = new BufferedWriter(new FileWriter(file, false));
// Write header
bufWr.append(sensorHeader.toString());
}
// Write frame
bufWr.append(sensorFrame.toString());
bufWr.flush();
Log.d(DEBUG_TAG, "Added frame to log");
} catch (IOException ex) {
// TODO: useful error handling
} finally {
// Cleanup
if (bufWr != null) {
try {
bufWr.close();
} catch (IOException ex) {
// TODO: useful error handling
}
}
}
return null;
}
}
我还有 2 个查询：
假设我想在移动文件之前在文件顶部附加一些信息，我该怎么做？
我的目标是在按下导出按钮时将 sensorLog.txt 文件从内部存储传输到外部存储。删除或清空内部sensorLog.txt文件，然后如果我再次按导出，同样的事情会再次发生，那么我在导出文件时必须重命名我的文件吗？不会有名字冲突吗？我该如何处理？我可以动态命名吗？
谢谢。
编辑：一些更正
View.OnClickListener export_handler = new View.OnClickListener() {
public void onClick(View v)
{
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state))
{
Log.d(DEBUG_TAG, "SD card detected");
stopSensorService();
Log.d(DEBUG_TAG, "stopSensorService for file transfer");
//make the timestamp the file name
long TS = System.currentTimeMillis();
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append(TS);
stringBuilder.append(".txt");
String file_name = stringBuilder.toString();
//file name stored in file_name
File file_ext = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOCUMENTS),file_name);
// attempt to create this new directory
//read from sensorLog.txt file
try
{
file_ext.createNewFile();
File file = getBaseContext().getFileStreamPath("sensorLog.txt");
if(file.exists())
{
FileInputStream read_file = openFileInput("sensorLog.txt");
//read contents of internal file
InputStreamReader inputStreamReader = new InputStreamReader(read_file);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
StringBuilder sb = new StringBuilder();
sb.append("Timestamp of export to SD"+TS+"/n");
String line;
while ((line = bufferedReader.readLine()) != null) {
sb.append(line);
}
BufferedWriter bufWr = null;
bufWr = new BufferedWriter(new FileWriter(file_ext, false));
// Write header
bufWr.append(sb.toString());
inputStreamReader.close();
bufWr.close();
read_file.close();
//delete sensor file once exported
getApplicationContext().deleteFile("sensorLog.txt");
}
}
catch(Exception e){}
但由于某种原因，我的文件没有存储在 SD 卡中。
【问题讨论】：
标签： android memory external file-transfer internal