内部存储项目

Question

大家好。这是我的项目。由于我是Java编程的初学者，我尝试使用不同类型的存储，现在是内部存储。我有一个接受用户名和密码的屏幕，保存时会保存一个文本文件david.txt。我进入第二个屏幕推送负载，信息从文本文件中提取并填充用户名和密码。

这是主要活动

public static final String TAG = "MainActivity"; 

EditText userName, password; 

//... standard stuff 

    userName = (EditText) findViewById(R.id.userName); 
    password = (EditText) findViewById(R.id.password); 
} 

public void save (View view) 
{ 
    String text1 = userName.getText().toString(); // example: David 
    String text2 = password.getText().toString(); // Example: Vilma123 
    File file=null; 
    text1=text1+" "; // Adds space between username and password 
    FileOutputStream fileOutputStream=null; 

     try { 
     file=getFilesDir(); //Gets directory of stored file 
     fileOutputStream = openFileOutput("david", Context.MODE_PRIVATE); 
     fileOutputStream.write(text1.getBytes()); 
     fileOutputStream.write(text2.getBytes()); 

    } catch (FileNotFoundException e) { 
     // TODO Auto-generated catch block 
     Log.d(TAG, e.toString()); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     Log.d(TAG, e.toString()); 
    } 
    finally{ 
     try { 
      fileOutputStream.close(); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      Log.d(TAG, e.toString()); 
     } 
    } 



    Toast.makeText(this, "Saved successfully"+file+" /david.txt", Toast.LENGTH_LONG).show(); 
} 

代码这个伟大工程，是我推“转到B”按钮，激活了SecondActivity页面中的“负荷”的方法在屏幕上：见下文

EditText userName, password; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_second); 

    userName = (EditText) findViewById(R.id.editText2); 
    password = (EditText) findViewById(R.id.editText4); 

} 
public void load (View view) 
{ 
     Log.d("david", "starting fileInputStream"); 

     try { 
      FileInputStream fileInputStream =  openFileInput("david.txt"); 
      int read = -1; //-1 indicates file is empty 
      StringBuffer buffer = new StringBuffer(); 

      while ((read = fileInputStream.read())!=-1); 
      { 
       buffer.append((char)read); 
      } 

       Log.d("david", buffer.toString()); 

       String user = buffer.substring(0, buffer.indexOf("")); 

       String pass = buffer.substring(buffer.indexOf("")+1); 

       userName.setText(user); 
       password.setText(pass); 

     fileInputStream.close(); 


    } catch (FileNotFoundException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 


    Toast.makeText(this, "Load successful", Toast.LENGTH_SHORT).show(); 
} 

好的，这是它开心的地方。当我按下Load按钮时，它应该加载我在最后一个屏幕中输入的用户名和密码，但它没有加载。 此日志文件有一个0值

Log.d("david", buffer.toString()); 

而其.txt文件中有我放在信息。有人能帮我解决这个问题吗？我没有显示任何错误，所有Toasts都应该显示。

Answer 1

public class Preference 
{ 

    // check for username length 
    public static String getUserName(Context context) 
    { 
    return PreferenceManager.getDefaultSharedPreferences(context).getString(
      "username", ""); 
    } 

    public static boolean setUserName(Context context,String username) 
    { 
    return PreferenceManager.getDefaultSharedPreferences(context.getApplicationContext()).edit() 
      .putString("username", username).commit(); 
    } 

// check for password length 
    public static String getPassword(Context context) 
    { 
    return PreferenceManager.getDefaultSharedPreferences(context.getApplicationContext()).getString(
      "password", ""); 
    } 


    public static boolean setPassword(Context context,String password) 
    { 
    return PreferenceManager.getDefaultSharedPreferences(context.getApplicationContext()).edit() 
      .putString("password", password).commit(); 
    } 


} 

Answer 2

你正在做一个小的错误，是在存储数据使用的是文件名david而你正在使用的文件名david.txt

在MainActivity retriving数据，更改以下行，

fileOutputStream = openFileOutput("david", Context.MODE_PRIVATE); 

这条线，

fileOutputStream = openFileOutput("david.txt", Context.MODE_PRIVATE);