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我正在嘗試編寫一個簡單的程序，將文件寫入外部存儲並從中讀取數據。以下是對問題的描述：
1.文件名=「hello_files.txt」包含文本「hello world」存儲在/sdcard中。
2.一旦寫入文件的數據被寫入，文件可以用adb看到。
3.然而，一旦應用程序被加載到手機上，並用第三方文件瀏覽器應用程序查看，似乎沒有文本寫入文件hello_files.txt.It似乎有問題的寫我的程序的一部分，但我無法弄清楚什麼。我在下面給出了代碼的兩個部分，用於寫作和閱讀。無法寫入或讀取外部存儲中的文件 - Android
從文件中讀取的代碼：
public void readFromFile() {
//Step 1. Check if the storage is available.
boolean mStorageAvailable;
boolean mStorageReadWrite;
String state = Environment.MEDIA_MOUNTED;
Log.v(this.toString(), "State of media = " + state);
if(Environment.MEDIA_MOUNTED.equals(state)) {
Log.v(this.toString(), "Media is mounted.");
mStorageAvailable = true;
mStorageReadWrite = true;
File dir = Environment.getExternalStorageDirectory();
String fileName = dir + "/" + file;
Log.v(this.toString(), "Reading from file = " + fileName);
File f = new File(dir, file);
FileReader fr = null;
try {
fr = new FileReader(f);
Log.v(this.toString(), "Wrapping a buffered reader around file reader.");
BufferedReader bufRead = new BufferedReader(fr, 8192);
//Log.v(this.toString(), bufRead.toString());
String line;
try {
line = bufRead.readLine();
Log.v(this.toString(), "Line read = " + line);
Toast.makeText(getApplicationContext(), line, Toast.LENGTH_SHORT).show();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.v(this.toString(), "IOException found in reading line from file.");
}
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
Log.v(this.toString(), "File not found for reading.");
}
}
}
用於寫文件的代碼是：
public void writeToFile() {
//Step 2. Check if external storage is mounted.
boolean mStorageExists;
boolean mStorageReadWrite;
String state = Environment.getExternalStorageState();
Log.v(this.toString(), "External media mounted state = " + state);
if(Environment.MEDIA_MOUNTED.equals(state)) {
//media is mounted.
//Mounted storage is read/write.
//Write to the file.
mStorageExists = true;
mStorageReadWrite = true;
Log.v(this.toString(), "Going to write to a file.");
//get directory.
File dir = Environment.getExternalStorageDirectory();
Log.v(this.toString(), "Root directory = " + dir.getAbsolutePath());
String fileName = dir.getAbsolutePath() + "/" + file;
Log.v(this.toString(), "File to write to is present at " + fileName);
File f = new File(dir, file);
FileOutputStream fos;
try {
fos = new FileOutputStream(f);
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
Log.v(this.toString(), "File not found.");
}
try {
fos = openFileOutput(file, MODE_WORLD_READABLE | MODE_WORLD_WRITEABLE);
Log.v(this.toString(), "Bytes of the string = " + str.getBytes().toString());
fos.write(str.getBytes());
//Log.v(this.toString(), "Local path = ");
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
Log.v(this.toString(), "File not found!!");
e.printStackTrace();
} catch (IOException e) {
Log.v(this.toString(), "IO Exception.");
e.printStackTrace();
}
} else if(Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
//media is mounted but read only.
mStorageExists = true;
mStorageReadWrite = false;
Log.v(this.toString(), "The media is read-only mounted.");
} else if((Environment.MEDIA_NOFS.equals(state)) || (Environment.MEDIA_REMOVED.equals(state)) || (Environment.MEDIA_UNMOUNTED.equals(state))) {
mStorageExists = false;
mStorageReadWrite = false;
Log.v(this.toString(), "There is some problem with the media.");
}
}
日誌（從Log詳細標籤）：
10-23 10:26:19.444: V/[email protected](466): Read from file button clicked.
10-23 10:26:19.444: V/[email protected](466): State of media = mounted
10-23 10:26:19.444: V/[email protected](466): Media is mounted.
10-23 10:26:19.444: V/[email protected](466): Reading from file = /sdcard/hello_files.txt
10-23 10:26:19.453: V/[email protected](466): Wrapping a buffered reader around file reader.
10-23 10:26:19.453: V/[email protected](466): Line read = null
請登錄後發表 –
。文件hello_files.txt只包含一行：hello world – Sriram
@SardorDushamov：任何幫助都是最受歡迎的..。 – Sriram