数据持久化存储

序列化存储磁盘

package com.example.myapplication;

import android.os.Bundle;
import android.util.Log;

import androidx.appcompat.app.AppCompatActivity;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private String TAG = "MainActivity";

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

        ArrayList<String> strings = new ArrayList<>();
        strings.add("a");
        strings.add("b");
        strings.add("c");

        //存储数据集合，也可以是实体类
        init(strings);
    }

    private void init(Serializable serializable) {
        try {
            Log.i(TAG, "init: " + serializable);
            String serialize = serialize(serializable);   //序列化
            Log.i(TAG, "序列化: " + serializable);
            ArrayList<String> serializable1 = (ArrayList<String>) deSerialization(serialize); //用序列化返回的信息取反序列化
            Log.i(TAG, "反序列化: " + serializable1);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }


    //序列化 存储在磁盘
    private static String serialize(Serializable serializable) throws IOException {
        long startTime = System.currentTimeMillis();
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
        objectOutputStream.writeObject(serializable);
        String serStr = byteArrayOutputStream.toString("ISO-8859-1");
        serStr = URLEncoder.encode(serStr, "UTF-8");
        objectOutputStream.close();
        byteArrayOutputStream.close();
        Log.d("MainActivity", "serialize str =" + serStr);
        long endTime = System.currentTimeMillis();
        Log.d("MainActivity", "序列化耗时为:" + (endTime - startTime));
        return serStr;
    }


    /**
     * 反序列化对象
     *
     * @param str
     * @return
     * @throws IOException
     * @throws ClassNotFoundException
     */
    private static Serializable deSerialization(String str) throws IOException, ClassNotFoundException {
        long startTime = System.currentTimeMillis();
        String redStr = URLDecoder.decode(str, "UTF-8");
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(redStr.getBytes("ISO-8859-1"));
        ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
        Serializable serializable = (Serializable) objectInputStream.readObject();
        objectInputStream.close();
        byteArrayInputStream.close();
        long endTime = System.currentTimeMillis();
        Log.d("MainActivity", "反序列化耗时为:" + (endTime - startTime));
        return serializable;
    }

}

日志如下