Android实现手机内存存储功能

package com.gaojc.activity;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import com.gaojc.text.R;
import com.gaojc.text.Utils.LogUtil;
import com.gaojc.text.Utils.SharedPreferencesUtil;

public class AddDataTestActivity extends AppCompatActivity {

    // 需要存入的数据（这里为了方便，所以使用假数据）
    private final static String CODE = "ABC666";

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


        /**
         * 存入数据
         */
        findViewById(R.id.saveData).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SharedPreferencesUtil.getInstance(AddDataTestActivity.this).putString("code",CODE);
            }
        });


        /**
         * 获取数据
         */
        findViewById(R.id.getData).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String code = SharedPreferencesUtil.getInstance(AddDataTestActivity.this).getString("code");
                Toast.makeText(AddDataTestActivity.this,"code：" + code,Toast.LENGTH_LONG).show();
                LogUtil.e("code：" + code);
            }
        });

    }
}

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.gaojc.activity.AddDataTestActivity">

    <Button
        android:id="@+id/saveData"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="存入"
        android:layout_gravity="left"/>

    <Button
        android:id="@+id/getData"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="获取"
        android:layout_gravity="right"/>

</FrameLayout>

package com.gaojc.text.Utils;

import android.content.Context;
import android.content.SharedPreferences;
import android.text.TextUtils;

public class SharedPreferencesUtil {

    private static SharedPreferences mSharedPreferences; //保存数据接口
    private static SharedPreferences.Editor mEditor; //Editor对象用来写入数据
    private static SharedPreferencesUtil mSharedPreferencesUtil;


    // 构造方法
    public SharedPreferencesUtil(Context context) {
        /**
         * context.getSharedPreferences：获取SharedPreferences实例
         *      Context.MODE_PRIVATE：指定该SharedPreferences数据只能被本应用程序读写
         */
        mSharedPreferences = context.getSharedPreferences("config", Context.MODE_PRIVATE);
        // 获取Editor对象
        mEditor = mSharedPreferences.edit();
    }

    // 单例模式
    public static SharedPreferencesUtil getInstance(Context context) {
        if (mSharedPreferencesUtil == null) {
            mSharedPreferencesUtil = new SharedPreferencesUtil(context);
        }
        return mSharedPreferencesUtil;
    }

    // 存入数据
    public void putString(String key, String value) {
        if (TextUtils.isEmpty(value)) {
            value = "";
        }
        // apply()：提交
        mEditor.putString(key, value).apply();
    }

    // 获取数据
    public String getString(String key) {
        return mSharedPreferences.getString(key, "");
    }
}