我想存储一个时间值,需要检索和编辑它。我如何使用SharedPreferences来做到这一点?


当前回答

使用这个简单的库,下面是如何调用SharedPreferences..

TinyDB tinydb = new TinyDB(context);

tinydb.putInt("clickCount", 2);

tinydb.putString("userName", "john");
tinydb.putBoolean("isUserMale", true); 

tinydb.putList("MyUsers", mUsersArray);
tinydb.putImagePNG("DropBox/WorkImages", "MeAtlunch.png", lunchBitmap);

//These plus the corresponding get methods are all Included

其他回答

我想在这里补充一点,当使用SharedPreferences时,这个问题的大多数代码片段都有类似MODE_PRIVATE的东西。MODE_PRIVATE意味着无论您写入这个共享首选项的是什么,都只能由您的应用程序读取。

Whatever key you pass to getSharedPreferences() method, android creates a file with that name and stores the preference data into it. Also remember that getSharedPreferences() is supposed to be used when you intend to have multiple preference files for your application. If you intend to use single preference file and store all key-value pairs into it then use the getSharedPreference() method. Its weird why everyone (including myself) simply uses getSharedPreferences() flavor without even understanding the difference between the above two.

下面的视频教程应该会有所帮助 https://www.youtube.com/watch?v=2PcAQ1NBy98

如何通过SharedPreferences存储登录值的简单解决方案。

您可以扩展MainActivity类或其他存储“想要保留的值”的类。把这些放到作者和读者课程中:

public static final String GAME_PREFERENCES_LOGIN = "Login";

这里InputClass是输入类,OutputClass是输出类。

// This is a storage, put this in a class which you can extend or in both classes:
//(input and output)
public static final String GAME_PREFERENCES_LOGIN = "Login";

// String from the text input (can be from anywhere)
String login = inputLogin.getText().toString();

// then to add a value in InputCalss "SAVE",
SharedPreferences example = getSharedPreferences(GAME_PREFERENCES_LOGIN, 0);
Editor editor = example.edit();
editor.putString("value", login);
editor.commit();

现在你可以在其他地方使用它,比如其他类。下面是OutputClass。

SharedPreferences example = getSharedPreferences(GAME_PREFERENCES_LOGIN, 0);
String userString = example.getString("value", "defValue");

// the following will print it out in console
Logger.getLogger("Name of a OutputClass".class.getName()).log(Level.INFO, userString);

使用这个例子简单明了

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.sairamkrishna.myapplication" >

   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/AppTheme" >

      <activity
         android:name=".MainActivity"
         android:label="@string/app_name" >

         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>

      </activity>

   </application>
</manifest>
public class MainActivity extends AppCompatActivity {
   EditText ed1,ed2,ed3;
   Button b1;

   public static final String MyPREFERENCES = "MyPrefs" ;
   public static final String Name = "nameKey";
   public static final String Phone = "phoneKey";
   public static final String Email = "emailKey";

   SharedPreferences sharedpreferences;

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

      ed1=(EditText)findViewById(R.id.editText);
      ed2=(EditText)findViewById(R.id.editText2);
      ed3=(EditText)findViewById(R.id.editText3);

      b1=(Button)findViewById(R.id.button);
      sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);

      b1.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            String n  = ed1.getText().toString();
            String ph  = ed2.getText().toString();
            String e  = ed3.getText().toString();

            SharedPreferences.Editor editor = sharedpreferences.edit();

            editor.putString(Name, n);
            editor.putString(Phone, ph);
            editor.putString(Email, e);
            editor.commit();
            Toast.makeText(MainActivity.this,"Thanks",Toast.LENGTH_LONG).show();
         }
      });
   }

}

我创建了一个Helper类来简化我的生活。这是一个泛型类,有很多在应用程序中常用的方法,如共享首选项,电子邮件有效性,日期时间格式。在代码中复制这个类,并在任何需要的地方访问它的方法。

 import android.app.AlertDialog;
 import android.app.ProgressDialog;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.SharedPreferences;
 import android.support.v4.app.FragmentActivity;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.EditText;
 import android.widget.Toast;

 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Random;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;

/**
* Created by Zohaib Hassan on 3/4/2016.
*/
 public class Helper {

private static ProgressDialog pd;

public static void saveData(String key, String value, Context context) {
    SharedPreferences sp = context.getApplicationContext()
            .getSharedPreferences("appData", 0);
    SharedPreferences.Editor editor;
    editor = sp.edit();
    editor.putString(key, value);
    editor.commit();
}

public static void deleteData(String key, Context context){
    SharedPreferences sp = context.getApplicationContext()
            .getSharedPreferences("appData", 0);
    SharedPreferences.Editor editor;
    editor = sp.edit();
    editor.remove(key);
    editor.commit();

}

public static String getSaveData(String key, Context context) {
    SharedPreferences sp = context.getApplicationContext()
            .getSharedPreferences("appData", 0);
    String data = sp.getString(key, "");
    return data;

}




public static long dateToUnix(String dt, String format) {
    SimpleDateFormat formatter;
    Date date = null;
    long unixtime;
    formatter = new SimpleDateFormat(format);
    try {
        date = formatter.parse(dt);
    } catch (Exception ex) {

        ex.printStackTrace();
    }
    unixtime = date.getTime();
    return unixtime;

}

public static String getData(long unixTime, String formate) {

    long unixSeconds = unixTime;
    Date date = new Date(unixSeconds);
    SimpleDateFormat sdf = new SimpleDateFormat(formate);
    String formattedDate = sdf.format(date);
    return formattedDate;
}

public static String getFormattedDate(String date, String currentFormat,
                                      String desiredFormat) {
    return getData(dateToUnix(date, currentFormat), desiredFormat);
}




public static double distance(double lat1, double lon1, double lat2,
                              double lon2, char unit) {
    double theta = lon1 - lon2;
    double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
            + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2))
            * Math.cos(deg2rad(theta));
    dist = Math.acos(dist);
    dist = rad2deg(dist);
    dist = dist * 60 * 1.1515;
    if (unit == 'K') {
        dist = dist * 1.609344;
    } else if (unit == 'N') {
        dist = dist * 0.8684;
    }
    return (dist);
}

/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts decimal degrees to radians : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double deg2rad(double deg) {
    return (deg * Math.PI / 180.0);
}

/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts radians to decimal degrees : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double rad2deg(double rad) {
    return (rad * 180.0 / Math.PI);
}

public static int getRendNumber() {
    Random r = new Random();
    return r.nextInt(360);
}

public static void hideKeyboard(Context context, EditText editText) {
    InputMethodManager imm = (InputMethodManager) context
            .getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(editText.getWindowToken(), 0);
}

public static void showLoder(Context context, String message) {
    pd = new ProgressDialog(context);

    pd.setCancelable(false);
    pd.setMessage(message);
    pd.show();
}

public static void showLoderImage(Context context, String message) {
    pd = new ProgressDialog(context);
    pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    pd.setCancelable(false);
    pd.setMessage(message);
    pd.show();
}

public static void dismissLoder() {
    pd.dismiss();
}

public static void toast(Context context, String text) {

    Toast.makeText(context, text, Toast.LENGTH_LONG).show();
}
/*
     public static Boolean connection(Context context) {
    ConnectionDetector connection = new ConnectionDetector(context);
    if (!connection.isConnectingToInternet()) {

        Helper.showAlert(context, "No Internet access...!");
        //Helper.toast(context, "No internet access..!");
        return false;
    } else
        return true;
}*/

public static void removeMapFrgment(FragmentActivity fa, int id) {

    android.support.v4.app.Fragment fragment;
    android.support.v4.app.FragmentManager fm;
    android.support.v4.app.FragmentTransaction ft;
    fm = fa.getSupportFragmentManager();
    fragment = fm.findFragmentById(id);
    ft = fa.getSupportFragmentManager().beginTransaction();
    ft.remove(fragment);
    ft.commit();

}

public static AlertDialog showDialog(Context context, String message) {
    AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setMessage(message);

    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int id) {
            // TODO Auto-generated method stub

        }
    });

    return builder.create();
}

public static void showAlert(Context context, String message) {
    AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setTitle("Alert");
    builder.setMessage(message)
            .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.dismiss();
                }
            }).show();
}

public static boolean isURL(String url) {
    if (url == null)
        return false;

    boolean foundMatch = false;
    try {
        Pattern regex = Pattern
                .compile(
                        "\\b(?:(https?|ftp|file)://|www\\.)?[-A-Z0-9+&#/%?=~_|$!:,.;]*[A-Z0-9+&@#/%=~_|$]\\.[-A-Z0-9+&@#/%?=~_|$!:,.;]*[A-Z0-9+&@#/%=~_|$]",
                        Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
        Matcher regexMatcher = regex.matcher(url);
        foundMatch = regexMatcher.matches();
        return foundMatch;
    } catch (PatternSyntaxException ex) {
        // Syntax error in the regular expression
        return false;
    }
}

public static boolean atLeastOneChr(String string) {
    if (string == null)
        return false;

    boolean foundMatch = false;
    try {
        Pattern regex = Pattern.compile("[a-zA-Z0-9]",
                Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
        Matcher regexMatcher = regex.matcher(string);
        foundMatch = regexMatcher.matches();
        return foundMatch;
    } catch (PatternSyntaxException ex) {
        // Syntax error in the regular expression
        return false;
    }
}

public static boolean isValidEmail(String email, Context context) {
    String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
    CharSequence inputStr = email;
    Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher(inputStr);
    if (matcher.matches()) {
        return true;
    } else {
        // Helper.toast(context, "Email is not valid..!");

        return false;
    }
}

public static boolean isValidUserName(String email, Context context) {
    String expression = "^[0-9a-zA-Z]+$";
    CharSequence inputStr = email;
    Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher(inputStr);
    if (matcher.matches()) {
        return true;
    } else {
        Helper.toast(context, "Username is not valid..!");
        return false;
    }
}

public static boolean isValidDateSlash(String inDate) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("dd/mm/yyyy");
    dateFormat.setLenient(false);
    try {
        dateFormat.parse(inDate.trim());
    } catch (ParseException pe) {
        return false;
    }
    return true;
}

public static boolean isValidDateDash(String inDate) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("dd-mm-yyyy");
    dateFormat.setLenient(false);
    try {
        dateFormat.parse(inDate.trim());
    } catch (ParseException pe) {
        return false;
    }
    return true;
}

public static boolean isValidDateDot(String inDate) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("dd.mm.yyyy");
    dateFormat.setLenient(false);
    try {
        dateFormat.parse(inDate.trim());
    } catch (ParseException pe) {
        return false;
    }
    return true;
}

}

您可以使用以下方法保存值:

public void savePreferencesForReasonCode(Context context,
    String key, String value) {
    SharedPreferences sharedPreferences = PreferenceManager
    .getDefaultSharedPreferences(context);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(key, value);
    editor.commit();
    }

使用这个方法,你可以从SharedPreferences中获取值:

public String getPreferences(Context context, String prefKey) {
  SharedPreferences sharedPreferences = PreferenceManager
 .getDefaultSharedPreferences(context);
 return sharedPreferences.getString(prefKey, "");
}

这里prefKey是用来保存特定值的键。谢谢。