Edit

SharedPreferences pref = getSharedPreferences("YourPref", MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putString("yourValue", value);
editor.commit();

Read

SharedPreferences pref = getSharedPreferences("YourPref", MODE_PRIVATE);
value= pref.getString("yourValue", "");

我为sharedpreferences写了一个helper类:

import android.content.Context;
import android.content.SharedPreferences;

/**
 * Created by mete_ on 23.12.2016.
 */
public class HelperSharedPref {

Context mContext;

public HelperSharedPref(Context mContext) {
    this.mContext = mContext;
}

/**
 *
 * @param key Constant RC
 * @param value Only String, Integer, Long, Float, Boolean types
 */
public void saveToSharedPref(String key, Object value) throws Exception {
    SharedPreferences.Editor editor = mContext.getSharedPreferences(key, Context.MODE_PRIVATE).edit();
    if (value instanceof String) {
        editor.putString(key, (String) value);
    } else if (value instanceof Integer) {
        editor.putInt(key, (Integer) value);
    } else if (value instanceof Long) {
        editor.putLong(key, (Long) value);
    } else if (value instanceof Float) {
        editor.putFloat(key, (Float) value);
    } else if (value instanceof Boolean) {
        editor.putBoolean(key, (Boolean) value);
    } else {
        throw new Exception("Unacceptable object type");
    }

    editor.commit();
}

/**
 * Return String
 * @param key
 * @return null default is null
 */
public String loadStringFromSharedPref(String key) throws Exception {
    SharedPreferences prefs = mContext.getSharedPreferences(key, Context.MODE_PRIVATE);
    String restoredText = prefs.getString(key, null);

    return restoredText;
}

/**
 * Return int
 * @param key
 * @return null default is -1
 */
public Integer loadIntegerFromSharedPref(String key) throws Exception {
    SharedPreferences prefs = mContext.getSharedPreferences(key, Context.MODE_PRIVATE);
    Integer restoredText = prefs.getInt(key, -1);

    return restoredText;
}

/**
 * Return float
 * @param key
 * @return null default is -1
 */
public Float loadFloatFromSharedPref(String key) throws Exception {
    SharedPreferences prefs = mContext.getSharedPreferences(key, Context.MODE_PRIVATE);
    Float restoredText = prefs.getFloat(key, -1);

    return restoredText;
}

/**
 * Return long
 * @param key
 * @return null default is -1
 */
public Long loadLongFromSharedPref(String key) throws Exception {
    SharedPreferences prefs = mContext.getSharedPreferences(key, Context.MODE_PRIVATE);
    Long restoredText = prefs.getLong(key, -1);

    return restoredText;
}

/**
 * Return boolean
 * @param key
 * @return null default is false
 */
public Boolean loadBooleanFromSharedPref(String key) throws Exception {
    SharedPreferences prefs = mContext.getSharedPreferences(key, Context.MODE_PRIVATE);
    Boolean restoredText = prefs.getBoolean(key, false);

    return restoredText;
}

}

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);

以函数的方式存储和检索全局变量。 要测试，请确保页面上有Textview项，取消代码中的两行注释并运行。然后再次注释这两行，然后运行。 这里TextView的id是用户名和密码。

在你想要使用它的每个Class中，在最后添加这两个例程。 我想这个例行程序是全球例行程序，但不知道如何。这个作品。

这些变量随处可见。 它将变量存储在“MyFile”中。你可以按自己的方式改变。

你称之为使用

 storeSession("username","frans");
 storeSession("password","!2#4%");***

变量username将用“frans”填充，密码为“!2#4%”。即使在重新启动后，它们仍然可用。

你用

 password.setText(getSession(("password")));
 usernames.setText(getSession(("username")));

下面是我的grid.java的全部代码

    package nl.yentel.yenteldb2;
    import android.content.SharedPreferences;
    import android.os.Bundle;
    import android.support.design.widget.FloatingActionButton;
    import android.support.design.widget.Snackbar;
    import android.support.v7.app.AppCompatActivity;
    import android.support.v7.widget.Toolbar;
    import android.view.View;
    import android.widget.EditText;
    import android.widget.TextView;

    public class Grid extends AppCompatActivity {
    private TextView usernames;
    private TextView password;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_grid);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

      ***//  storeSession("username","frans.eilering@gmail.com");
        //storeSession("password","mijn wachtwoord");***
        password = (TextView) findViewById(R.id.password);
        password.setText(getSession(("password")));
        usernames=(TextView) findViewById(R.id.username);
        usernames.setText(getSession(("username")));
    }

    public void storeSession(String key, String waarde) { 
        SharedPreferences pref = getApplicationContext().getSharedPreferences("MyFile", MODE_PRIVATE);
        SharedPreferences.Editor editor = pref.edit();
        editor.putString(key, waarde);
        editor.commit();
    }

    public String getSession(String key) {
//http://androidexample.com/Android_SharedPreferences_Basics/index.php?view=article_discription&aid=126&aaid=146
        SharedPreferences pref = getApplicationContext().getSharedPreferences("MyFile", MODE_PRIVATE);
        SharedPreferences.Editor editor = pref.edit();
        String output = pref.getString(key, null);
        return output;
    }

    }

下面是textview项

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="usernames"
    android:id="@+id/username"
    android:layout_below="@+id/textView"
    android:layout_alignParentStart="true"
    android:layout_marginTop="39dp"
    android:hint="hier komt de username" />

 <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="password"
    android:id="@+id/password"
    android:layout_below="@+id/user"
    android:layout_alignParentStart="true"
    android:hint="hier komt het wachtwoord" />

编辑sharedpreference中的数据

 SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
 editor.putString("text", mSaved.getText().toString());
 editor.putInt("selection-start", mSaved.getSelectionStart());
 editor.putInt("selection-end", mSaved.getSelectionEnd());
 editor.apply();

从sharedpreference中检索数据

SharedPreferences prefs = getPreferences(MODE_PRIVATE); 
String restoredText = prefs.getString("text", null);
if (restoredText != null) 
{
  //mSaved.setText(restoredText, TextView.BufferType.EDITABLE);
  int selectionStart = prefs.getInt("selection-start", -1);
  int selectionEnd = prefs.getInt("selection-end", -1);
  /*if (selectionStart != -1 && selectionEnd != -1)
  {
     mSaved.setSelection(selectionStart, selectionEnd);
  }*/
}

Edit

我从API Demo样本中截取了这个片段。它有一个编辑文本框。在这种情况下，它不是必需的。我也有同样的看法。

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