SharedPreferences

SharedPreferences用于Android本地存储，使用较简单。SharedPreferences本身是一个接口，它的实现类是SharedPreferencesImpl，通过源码可以发现他的put和get方法都有synchronized锁，因此它是线程安全的。

        SharedPreferences sp = context.getSharedPreferences("sp_storage", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = getPreferences().edit();
        editor.putString("name", "小明");
        editor.apply();
//        editor.commit();

apply和commit的区别

editor.apply()会先存入内存，后续才同步到磁盘，比commit效率高，特别是频繁存取的时候。
editor.commit()会直接写入磁盘，并且返回boolean表示是否写入成功，适合需要根据是否成功写入磁盘这个结果做后续操作的情景使用。

        SharedPreferences sp = context.getSharedPreferences("sp_storage", Context.MODE_PRIVATE);
        sp.getString("name", "");

//封装成Util
public class SPHelper {
    public static volatile SharedPreferences mSharedPreferences;

    public static void set(String key, int value) {
        SharedPreferences.Editor editor = getPreferences().edit();
        editor.putInt(key, value);
        editor.apply();
    }

    public static void set(String key, boolean value) {
        SharedPreferences.Editor editor = getPreferences().edit();
        editor.putBoolean(key, value);
        editor.apply();
    }

    public static void set(String key, String value) {
        SharedPreferences.Editor editor = getPreferences().edit();
        editor.putString(key, value);
        editor.apply();
    }

    public static void set(String key, long value) {
        SharedPreferences.Editor editor = getPreferences().edit();
        editor.putLong(key, value);
        editor.apply();
    }

    public static boolean get(String key, boolean defValue) {
        return getPreferences().getBoolean(key, defValue);
    }

    public static String get(String key, String defValue) {
        return getPreferences().getString(key, defValue);
    }

    public static int get(String key, int defValue) {
        return getPreferences().getInt(key, defValue);
    }

    public static long get(String key, long defValue) {
        return getPreferences().getLong(key, defValue);
    }

    public static float get(String key, float defValue) {
        return getPreferences().getFloat(key, defValue);
    }

    public static SharedPreferences getPreferences() {
        if (mSharedPreferences == null) {
            synchronized (SPHelper.class) {
                if (mSharedPreferences == null) {
                    return baseApplication.getContext().getSharedPreferences("sp_storage", Context.MODE_PRIVATE);
                }
            }
        }
        return mSharedPreferences;
    }
}


//使用
//存
SPHelper.set("name", "小明");
//取
String name = SPHelper.get("name", "");