Android Studio 檔案讀寫

讀寫權限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

取得儲存路徑

• getDataDirectory()
• 取得手機內存根目錄
• getDownloadCacheDirectory()
• 取得手機暫存
• getRootDirectory()
• 取得手機系統目錄
• getExternalStorageDirectory()
• 取得手機外部儲存SD Card目錄

取得路徑的格式

• getPath()
• 取得定義的路徑
• getAbsolutePath()
• 取得絕對路徑
• getCanonicalPath()
• 取得符合路徑規範的路徑

File file = new File("TXT/./test.txt");
Log.d("frilgetPath","=="+file.getPath());
Log.d("frilAbsolutePath","=="+file.getAbsolutePath());
Log.d("frilCanonicalPath","=="+file.getCanonicalPath());

結果如下

      
D/frilgetPath: ==TXT/./test.txt
D/frilAbsolutePath: ==/TXT/./test.txt
D/frilCanonicalPath: ==/TXT/test.txt
      

Text讀取

try{
    FileReader fw = new FileReader(Environment.getExternalStorageDirectory().getAbsolutePath()+"/TXT/T.txt");
    BufferedReader bw = new BufferedReader(fw); //將BufferedWeiter與FileWrite物件做連結
    String thisLine ;//獲得讀取的每行資料
    String txtshow = "";
    while ((thisLine = bw.readLine()) != null) {
        txtshow = txtshow + thisLine +"\n\r";
    }
    txt.setText(txtshow);//使用TextView承接
    bw.close();

}catch(IOException e){
    e.printStackTrace();
}

Text寫檔

try{
    File storage = Environment.getExternalStorageDirectory();
    File file = new File(storage, "TXT");
    if (! file.exists())//判斷檔案是否存在
    {
        file.mkdir();//建立檔案
    }
    File newTextFile = new File(storage.getPath() + "/TXT" ,"T.txt");

    if (! newTextFile.exists())
    {
        newTextFile.createNewFile();//建立文件
    }
    FileWriter fw = new FileWriter(newTextFile,true);//(檔案位置, 是否接續寫入)
    BufferedWriter bw = new BufferedWriter(fw); //將BufferedWeiter與FileWrite物件做連結
    bw.write(editText.getText().toString());//寫入EditText的資料
    bw.newLine();
    bw.close();
}catch(IOException e){
    e.printStackTrace();
}

額外參考

Android Studio 寫入檔案PC無法顯示