一、Parcelable和Serializable

对象的序列化是把Java对象转化为字节序列并存储至一个存储媒介&＃xff08;硬盘或者内存&＃xff09;的过程&＃xff0c;反序列化则是把字节序列恢复为Java对象的过程&＃xff0c;但它们仅处理Java变量而不处理方法。

序列化的原因&＃xff1a;

• 永久性保存对象&＃xff0c;保存对象的字节序列到本地文件中。Serializable
• 通过序列化对象在网络中传递对象。Serializable
• 通过序列化在进程间传递对象。Parcelable

两种序列化的区别&＃xff1a;

• Serializable只需要对某个类以及它的属性实现Serializable接口即可&＃xff0c;它的缺点是使用了反射&＃xff0c;序列化的过程比较慢&＃xff0c;这种机制会在序列化的时候创建许多的临时对象&＃xff0c;容易引发频繁的gc。
• 而Parcelable是Android平台特有的&＃xff0c;在使用内存的时候性能更好&＃xff0c;但Parcelable不能使用在要将数据存储在磁盘的情况下&＃xff0c;因为Parcelable不能很好的保证数据的持续性在外界有变化的情况。

二、序列化在Android平台上的应用

2.1 通过intent传递复杂对象

intent支持传递的数据类型包括&＃xff1a;

• 基本类型的数据、及其数组。
• String/CharSequence类型的数据、及其数组。
• Parcelable/Serializable&＃xff0c;及其数组/列表数据。

2.2 SharePreference存储复杂对象

三、Serializable和Parcelable

3.1 使用Serializable的读写操作

首先定义我们要序列化的对象。

public class SBook implements Serializable { public int id; public String name;
}


进行读写操作&＃xff1a;

private void readSerializable() {ObjectInputStream object &＃61; null;try {FileInputStream out &＃61; new FileInputStream(Environment.getExternalStorageDirectory() &＃43; "/sbook.txt");object &＃61; new ObjectInputStream(out);SBook book &＃61; (SBook) object.readObject();if (book !&＃61; null) {Log.d(TAG, "book, id&＃61;" &＃43; book.id &＃43; ",name&＃61;" &＃43; book.name);} else {Log.d(TAG, "book is null");}} catch (Exception e) {Log.d(TAG, "readSerializable:" &＃43; e);} finally {try {if (object !&＃61; null) {object.close();}} catch (Exception e) {Log.d(TAG, "readSerializable:" &＃43; e);}}}private void writeSerializable() {SBook book &＃61; new SBook();book.id &＃61; 1;book.name &＃61; "SBook";ObjectOutputStream object &＃61; null;try {FileOutputStream out &＃61; new FileOutputStream(Environment.getExternalStorageDirectory() &＃43; "/sbook.txt");object &＃61; new ObjectOutputStream(out);object.writeObject(book);object.flush();} catch (Exception e) {Log.d(TAG, "writeSerializable:" &＃43; e);} finally {try {if (object !&＃61; null) {object.close();}} catch (Exception e) {Log.d(TAG, "writeSerializable:" &＃43; e);}}}


3.2 使用Parcelable的读写操作

定义序列化对象&＃xff1a;

public class PBook implements Parcelable {public int id;public String name;public PBook(int id, String name) {this.id &＃61; id;this.name &＃61; name;}private PBook(Parcel in) {id &＃61; in.readInt();name &＃61; in.readString();}public static final Parcelable.Creator CREATOR &＃61; new Parcelable.Creator() {&＃64;Overridepublic PBook[] newArray(int size) {return new PBook[size];}&＃64;Overridepublic PBook createFromParcel(Parcel source) {return new PBook(source);}};&＃64;Overridepublic int describeContents() {return 0;}&＃64;Overridepublic void writeToParcel(Parcel dest, int flags) {dest.writeInt(id);dest.writeString(name);}
}


写入和读取&＃xff1a;

private Intent writeParcelable() {PBook tony &＃61; new PBook(1, "tony");PBook king &＃61; new PBook(2, "king");ArrayList list &＃61; new ArrayList<>();list.add(tony);list.add(king);Intent intent &＃61; new Intent();intent.putParcelableArrayListExtra("PBook", list);return intent;}private void readParcelable(Intent intent) {if (intent !&＃61; null) {ArrayList list &＃61; intent.getParcelableArrayListExtra("PBook");if (list !&＃61; null) {for (PBook book : list) {Log.d(TAG, "readParcelable, id&＃61;" &＃43; book.id &＃43; ", name&＃61;" &＃43; book.name);}}}}


四、SharePreference存储复杂对象

//obejct -> ObjectOutputStream(ByteArrayOutputStream) -> ByteArrayOutputStream() -> byte[] -> String -> spprivate void writeSP() {SBook book &＃61; new SBook();book.id &＃61; 2;book.name &＃61; "sp";SharedPreferences sp &＃61; getSharedPreferences("SBookSP", MODE_PRIVATE);ByteArrayOutputStream os &＃61; new ByteArrayOutputStream();try {ObjectOutputStream object &＃61; new ObjectOutputStream(os);object.writeObject(book);String base64 &＃61; new String(Base64.encode(os.toByteArray(), Base64.DEFAULT));SharedPreferences.Editor editor &＃61; sp.edit();editor.putString("SBook", base64);editor.apply();} catch (Exception e) {}}//sp -> string -> byte[] -> ByteArrayInputStream(byte[]) -> ObjectInputStream(ByteArrayInputStream) -> objectprivate void readSP() {SharedPreferences sp &＃61; getSharedPreferences("SBookSP", MODE_PRIVATE);String sbook &＃61; sp.getString("SBook", "");if (sbook.length() > 0) {byte[] base64 &＃61; Base64.decode(sbook.getBytes(), Base64.DEFAULT);ByteArrayInputStream is &＃61; new ByteArrayInputStream(base64);try {ObjectInputStream object &＃61; new ObjectInputStream(is);SBook book &＃61; (SBook) object.readObject();if (book !&＃61; null) {Log.d(TAG, "readSP, id&＃61;" &＃43; book.id &＃43; ", name&＃61;" &＃43; book.name);}} catch (Exception e) {}}}