Android SharedPreferences数据存储工具类。需要用到Application类，这个是全局启动类。

实现的效果如图所示

1.主活动MainActivity类。代码内容如下

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity  {
    
    

    Button btn_1,btn_2;
    TextView tv_nr;

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

        tv_nr = (TextView) findViewById(R.id.tv_nr);
        btn_1 = (Button) findViewById(R.id.btn_1);
        btn_1.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                SpUtils.getInstance().putString("setting","我正在设置");
            }
        });

        btn_2 = (Button) findViewById(R.id.btn_2);
        btn_2.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                tv_nr.setText(SpUtils.getInstance().getString("setting"));
            }
        });
        
    }
}

2.主活动MainActivity类的activity_main布局代码如下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="sp存数据" />

        <Button
            android:id="@+id/btn_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="sp取数据" />
    </LinearLayout>

    <TextView
        android:id="@+id/tv_nr"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:gravity="center"
        android:textColor="@color/black"
        android:textSize="24sp" />
</LinearLayout>

3.SharedPreferences的工具类SpUtils。代码内容如下

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

public class SpUtils {
    
    
    private final static String SP_NAME = "setting";
    private SharedPreferences sharedPreferences = null;
    private static SpUtils spUtils = null;

    public static SpUtils getInstance() {
    
    
        if (spUtils == null) {
    
    
            return newInstance();
        }
        return spUtils;
    }

    private synchronized static SpUtils newInstance() {
    
    
        if (spUtils == null) {
    
    
            spUtils = new SpUtils();
        }
        return spUtils;
    }

    public SharedPreferences.Editor getEditor() {
    
    
        return sharedPreferences.edit();
    }

    //sp存数据
    public void putString(String key, String value) {
    
    
        getEditor().putString(key, value).apply();
    }

    //sp取数据
    public String getString(String key) {
    
    
        return sharedPreferences.getString(key, "暂无保存的数据");
        //"暂无保存的数据"为该key为空时的默认返回值
    }

    public int getInt(String key) {
    
    
        return sharedPreferences.getInt(key, 0);
    }

    public Long getLong(String key) {
    
    
        return sharedPreferences.getLong(key, 0);
    }

    public boolean getBoolean(String key) {
    
    
        return sharedPreferences.getBoolean(key, false);
    }

    private SpUtils() {
    
    
        sharedPreferences = App.getInstance().getSharedPreferences(SP_NAME, Context.MODE_PRIVATE);
    }

}

4.App继承Application类的启动类。代码内容如下

import android.app.Application;
import android.content.Context;
import android.content.res.Configuration;
import android.util.Log;

public class App extends Application {
    
    

    static Context context;
    public static Context getInstance() {
    
    
        return context;
    }

    /*
    Aplication创建时被调用，可以在该方法里进行一些初始化操作
     */
    @Override
    public void onCreate() {
    
    
        super.onCreate();
        Log.d("111333","Aplication创建被调用");
        context=getApplicationContext();
    }

    /*
    系统配置发生变更 的时候被调用 如：屏幕方向更改 、系统语言更改
     */
    @Override
    public void onConfigurationChanged(Configuration newConfig) {
    
    
        super.onConfigurationChanged(newConfig);
    }
    /*
    系统内存吃紧时被调用，用于释放内存
     */
    @Override
    public void onLowMemory() {
    
    
        super.onLowMemory();
    }
}

需要在AndroidManifest.xml文件中进行全局类配置。不配置是不会启动自定义的全局类的。完整的代码内容如下

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

    <application
        android:name=".App"
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyApplication002"
        tools:targetApi="31" >
        <activity
            android:name=".MainActivity"
            android:exported="true" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

</manifest>

需要配置的是这个地方，请看下图