android将对象序列化到文件：直接写文件与用Serializable接口的对比

1.用文件读写1024个对象的日志

10-09 16:12:44.493 6385-6385/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 230 ms
10-09 16:12:44.546 6385-6385/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 52 ms

10-09 16:31:23.964 24295-24295/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 241 ms
10-09 16:31:24.011 24295-24295/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 47 ms

10-09 16:31:48.225 24888-24888/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 225 ms
10-09 16:31:48.272 24888-24888/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 46 ms

10-09 16:32:44.947 26161-26161/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 230 ms
10-09 16:32:44.995 26161-26161/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 47 ms

2.用Serializable序列化接口1024个对象的日志

10-09 16:17:34.203 9878-9878/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 504 ms
10-09 16:17:34.295 9878-9878/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 90 ms

10-09 16:24:15.843 18643-18643/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 523 ms
10-09 16:24:15.943 18643-18643/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 99 ms

10-09 16:25:34.634 20412-20412/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 560 ms
10-09 16:25:34.727 20412-20412/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 91 ms

10-09 16:30:52.559 23712-23712/com.example.tt.downtest D/Serializable_TAG: write 1024 apples need 513 ms
10-09 16:30:52.654 23712-23712/com.example.tt.downtest D/Serializable_TAG: read 1024 apples need 94 ms 

3.结论

　　1w,10w,100w,不测试了,直接写文件.

4.示例

 package com.example.tt.downtest;

 import android.util.Log;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.RandomAccessFile;
 import java.io.Serializable;
 import java.util.ArrayList;

 public class Apple implements Serializable{

     static final String TAG = "Serializable_TAG";
     static final long serialVersionUID = 10000000000000000L;

     public int      mID;
     public String mName;
     public String   mClass;

     @Override
     public String toString() {
         return "Apple{" +
                 "mID = " + mID +
                 ", mName = '" + mName + '\'' +
                 ", mClass = '" + mClass + '\'' +
                 '}';
     }

 /*
     //自定义的简单加密，把id加密了。
    private void readObject(ObjectInputStream in) {
        try {
            //readFields是个键值对，也可以直接用in.readInt()等.写的时候用out.writeFields();才能与in.readFields()匹配，
            ObjectInputStream.GetField readFields = in.readFields();
            mID = readFields.get("mID", -1) - 11;  //自定义的简单加密，把id加密了。
            mName = (String) readFields.get("mName","default-mName");

        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    private void writeObject(ObjectOutputStream out){
        try {
            ObjectOutputStream.PutField fields = out.putFields();
            fields.put("mID",mID + 11);                 //自定义的简单加密，把id加密了。
            fields.put("mName",mName );
            out.writeFields();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }*/

     private void readObject(ObjectInputStream in) {
         try {
             mID = in.readInt();
             mName = in.readUTF();
             mClass = in.readUTF();
         } catch (IOException e) {
             Log.d(TAG, "IOException " + e.getMessage());
         }
     }
     private void writeObject(ObjectOutputStream out){
         try {
             out.writeInt(mID);
             out.writeUTF(mName);
             out.writeUTF(mClass);

         } catch (IOException e) {
             Log.d(TAG, "IOException " + e.getMessage());
         }
     }
     static void testNObject(File path){
         int len = ;
         long begin,end;
         ArrayList<Apple> writeApples = new ArrayList<>(len);
         String file = path + "/apple.n";

         for (int i =  ; i < len;++i){
             Apple apple = new Apple();
             apple.mID = i;
             apple.mName = "name" + i;
             apple.mClass = "class" + i ;
             writeApples.add(apple);
         }
         try {
             //write
             FileOutputStream fos = new FileOutputStream(file);
             ObjectOutputStream oos = new ObjectOutputStream(fos);
             begin = System.currentTimeMillis();
             for (int i = ; i < len;++i){
                 Apple app = writeApples.get(i);
                 oos.writeObject(app);
             }
             end = System.currentTimeMillis();
             Log.d(TAG, "write " +  len + " apples need " + (end - begin) + " ms");
             oos.close();
             fos.close();

             //read
             ArrayList<Apple> readApples = new ArrayList<>(len);
             FileInputStream fis = new FileInputStream(file);
             ObjectInputStream ois = new ObjectInputStream(fis);

             begin = System.currentTimeMillis();
             for (int i = ; i < len; ++i) {
                 Apple apple = (Apple) ois.readObject();
                 readApples.add(apple);
             }
             end = System.currentTimeMillis();
             Log.d(TAG, "read " +  len + " apples need " + (end - begin) + " ms");
             ois.close();
             fis.close();

             for (int i =  ; i < len; ++i){
                 Apple apple = readApples.get(i);
                 Log.d(TAG, apple.toString());
             }

         } catch (FileNotFoundException e) {
             Log.d(TAG, "FileNotFoundException " + e.getMessage());
         } catch (IOException e) {
             Log.d(TAG, "IOException " + e.getMessage());
         } catch (ClassNotFoundException e) {
             Log.d(TAG, "ClassNotFoundException " + e.getMessage());
         }
     }

     static void testNFiles(File path){
         int len = ;
         long begin,end;

         String file = path + "/apple.list";
         ArrayList<Apple> apples = new ArrayList<>(len);
         for (int i =  ; i < len; ++i){
             Apple app = new Apple();
             app.mID = i;
             app.mName = "name" + i;
             app.mClass = "class" + i;
             apples.add(app);
         }
         try {
             //write
             RandomAccessFile writer = new RandomAccessFile(file,"rw");

             begin = System.currentTimeMillis();
             writer.writeInt(len);
             for (int i = ;i < len; ++i){
                 Apple app = apples.get(i);
                 writer.writeInt(app.mID);
                 writer.writeUTF(app.mName);
                 writer.writeUTF(app.mClass);
             }
             writer.close();
             end = System.currentTimeMillis();
             Log.d(TAG, "write " +  len + " apples need " + (end - begin) + " ms");

             //read
             RandomAccessFile reader = new RandomAccessFile(file,"rw");
             len = reader.readInt();
             ArrayList<Apple> readApples = new ArrayList<>(len);

             begin = System.currentTimeMillis();
             for (int i = ; i < len; ++i) {
                 Apple app = new Apple();
                 app.mID = reader.readInt();
                 app.mName = reader.readUTF();
                 app.mClass = reader.readUTF();
                 readApples.add(app);
             }
             reader.close();
             end = System.currentTimeMillis();
             Log.d(TAG, "read " +  len + " apples need " + (end - begin) + " ms");

             for (int i = ; i < len; ++i){
                 Apple app = readApples.get(i);
                 Log.d(TAG, app.toString());
             }

         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
     }

     public static void testSerializable(File path){
 //        testNObject(path);
         testNFiles(path);
     }
 }