你好！在今天的课程中，我们将讨论 Java 中的序列化和反序列化。我们将从一个简单的例子开始。假设您是一名电脑游戏开发人员。如果你在 90 年代长大并记得那个时代的游戏机，你可能知道他们缺少我们今天认为理所当然的东西——保存和加载游戏的能力 :) 如果没有，想象一下！![Java 中的序列化和反序列化 - 1]()
恐怕今天没有这些能力的游戏就完蛋了！无论如何，“保存”和“加载”游戏是什么意思？好吧，我们理解日常含义：我们想从我们离开的地方继续游戏。为此，我们创建了一个稍后用于加载游戏的特定“检查点”。但这对程序员而不是休闲游戏玩家意味着什么？答案很简单：我们保存程序的状态。假设您在一款战略游戏中玩西班牙。您的游戏具有状态：每个人拥有哪些领土，每个人拥有多少资源，存在哪些联盟以及与谁结盟，谁处于战争状态，等等。这些信息，即我们程序的状态，必须以某种方式保存，以便恢复数据并继续游戏。当它发生的时候， Java 中的序列化是将对象的状态保存为字节序列的过程。 Java 中的反序列化是从这些字节中恢复对象的过程。任何 Java 对象都可以转换为字节序列。我们为什么需要这个？我们一再说过，程序本身并不存在。大多数情况下，它们会相互交互、交换数据等。字节格式对此既方便又高效。例如，我们可以转换SavedGame的一个对象class 转换成字节序列，通过网络将这些字节传输到另一台计算机，然后在另一台计算机上将这些字节转换回 Java 对象！听起来很难吧？似乎很难让这一切发生：/幸运的是，事实并非如此！:) 在Java中，Serializable接口负责序列化过程。这个接口非常简单：您不必实现一个方法就可以使用它！看看我们保存游戏的类是多么简单：
![Java university]()
![Java 中的序列化和反序列化 - 2]()
在 Java 中，这类问题是通过transient关键字解决的。如果将此关键字添加到类的某个字段，则该字段不会被序列化。让我们尝试使我们的SavedGame类的字段之一成为瞬态，然后我们将序列化并恢复单个对象。
![Java webinar]()
恐怕今天没有这些能力的游戏就完蛋了！无论如何，“保存”和“加载”游戏是什么意思？好吧，我们理解日常含义：我们想从我们离开的地方继续游戏。为此，我们创建了一个稍后用于加载游戏的特定“检查点”。但这对程序员而不是休闲游戏玩家意味着什么？答案很简单：我们保存程序的状态。假设您在一款战略游戏中玩西班牙。您的游戏具有状态：每个人拥有哪些领土，每个人拥有多少资源，存在哪些联盟以及与谁结盟，谁处于战争状态，等等。这些信息，即我们程序的状态，必须以某种方式保存，以便恢复数据并继续游戏。当它发生的时候， Java 中的序列化是将对象的状态保存为字节序列的过程。 Java 中的反序列化是从这些字节中恢复对象的过程。任何 Java 对象都可以转换为字节序列。我们为什么需要这个？我们一再说过，程序本身并不存在。大多数情况下，它们会相互交互、交换数据等。字节格式对此既方便又高效。例如，我们可以转换SavedGame的一个对象class 转换成字节序列，通过网络将这些字节传输到另一台计算机，然后在另一台计算机上将这些字节转换回 Java 对象！听起来很难吧？似乎很难让这一切发生：/幸运的是，事实并非如此！:) 在Java中，Serializable接口负责序列化过程。这个接口非常简单：您不必实现一个方法就可以使用它！看看我们保存游戏的类是多么简单：
import java.io.Serializable;
import java.util.Arrays;
public class SavedGame implements Serializable {
private static final long serialVersionUID = 1L;
private String[] territoryInfo;
private String[] resourceInfo;
private String[] diplomacyInfo;
public SavedGame(String[] territoryInfo, String[] resourceInfo, String[] diplomacyInfo){
this.territoryInfo = territoryInfo;
this.resourceInfo = resourceInfo;
this.diplomacyInfo = diplomacyInfo;
}
public String[] getTerritoryInfo() {
return territoryInfo;
}
public void setTerritoryInfo(String[] territoryInfo) {
this.territoryInfo = territoryInfo;
}
public String[] getResourceInfo() {
return resourceInfo;
}
public void setResourceInfo(String[] resourceInfo) {
this.resourceInfo = resourceInfo;
}
public String[] getDiplomacyInfo() {
return diplomacyInfo;
}
public void setDiplomacyInfo(String[] diplomacyInfo) {
this.diplomacyInfo = diplomacyInfo;
}
@Override
public String toString() {
return "SavedGame{" +
"territoryInfo=" + Arrays.toString(territoryInfo) +
", resourceInfo=" + Arrays.toString(resourceInfo) +
", diplomacyInfo=" + Arrays.toString(diplomacyInfo) +
'}';
}
}
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
public class Main {
public static void main(String[] args) throws IOException {
// Create our object
String[] territoryInfo = {"Spain has 6 provinces", "Russia has 10 provinces", "France has 8 provinces"};
String[] resourceInfo = {"Spain has 100 gold", "Russia has 80 gold", "France has 90 gold"};
String[] diplomacyInfo = {"France is at war with Russia, Spain has taken a neutral position"};
SavedGame savedGame = new SavedGame(territoryInfo, resourceInfo, diplomacyInfo);
// Create 2 streams to serialize the object and save it to a file
FileOutputStream outputStream = new FileOutputStream("C:\\Users\\Username\\Desktop\\save.ser");
ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
// Save the game to a file
objectOutputStream.writeObject(savedGame);
// Close the stream and release resources
objectOutputStream.close();
}
}
import java.io.*;
public class Main {
public static void main(String[] args) throws IOException, ClassNotFoundException {
FileInputStream fileInputStream = new FileInputStream("C:\\Users\\Username\\Desktop\\save.ser");
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
SavedGame savedGame = (SavedGame) objectInputStream.readObject();
System.out.println(savedGame);
}
}
public class TerritoryInfo {
private String info;
public TerritoryInfo(String info) {
this.info = info;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
@Override
public String toString() {
return "TerritoryInfo{" +
"info='" + info + '\'' +
'}';
}
}
public class ResourceInfo {
private String info;
public ResourceInfo(String info) {
this.info = info;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
@Override
public String toString() {
return "ResourceInfo{" +
"info='" + info + '\'' +
'}';
}
}
public class DiplomacyInfo {
private String info;
public DiplomacyInfo(String info) {
this.info = info;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
@Override
public String toString() {
return "DiplomacyInfo{" +
"info='" + info + '\'' +
'}';
}
}
import java.io.Serializable;
import java.util.Arrays;
public class SavedGame implements Serializable {
private TerritoryInfo territoryInfo;
private ResourceInfo resourceInfo;
private DiplomacyInfo diplomacyInfo;
public SavedGame(TerritoryInfo territoryInfo, ResourceInfo resourceInfo, DiplomacyInfo diplomacyInfo) {
this.territoryInfo = territoryInfo;
this.resourceInfo = resourceInfo;
this.diplomacyInfo = diplomacyInfo;
}
public TerritoryInfo getTerritoryInfo() {
return territoryInfo;
}
public void setTerritoryInfo(TerritoryInfo territoryInfo) {
this.territoryInfo = territoryInfo;
}
public ResourceInfo getResourceInfo() {
return resourceInfo;
}
public void setResourceInfo(ResourceInfo resourceInfo) {
this.resourceInfo = resourceInfo;
}
public DiplomacyInfo getDiplomacyInfo() {
return diplomacyInfo;
}
public void setDiplomacyInfo(DiplomacyInfo diplomacyInfo) {
this.diplomacyInfo = diplomacyInfo;
}
@Override
public String toString() {
return "SavedGame{" +
"territoryInfo=" + territoryInfo +
", resourceInfo=" + resourceInfo +
", diplomacyInfo=" + diplomacyInfo +
'}';
}
}
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
public class Main {
public static void main(String[] args) throws IOException {
// Create our object
TerritoryInfo territoryInfo = new TerritoryInfo("Spain has 6 provinces, Russia has 10 provinces, France has 8 provinces");
ResourceInfo resourceInfo = new ResourceInfo("Spain has 100 gold, Russia has 80 gold, France has 90 gold");
DiplomacyInfo diplomacyInfo = new DiplomacyInfo("France is at war with Russia, Spain has taken a neutral position");
SavedGame savedGame = new SavedGame(territoryInfo, resourceInfo, diplomacyInfo);
FileOutputStream fileOutputStream = new FileOutputStream("C:\\Users\\Username\\Desktop\\save.ser");
ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
objectOutputStream.writeObject(savedGame);
objectOutputStream.close();
}
}
在 Java 中，这类问题是通过transient关键字解决的。如果将此关键字添加到类的某个字段，则该字段不会被序列化。让我们尝试使我们的SavedGame类的字段之一成为瞬态，然后我们将序列化并恢复单个对象。
import java.io.Serializable;
public class SavedGame implements Serializable {
private transient TerritoryInfo territoryInfo;
private ResourceInfo resourceInfo;
private DiplomacyInfo diplomacyInfo;
public SavedGame(TerritoryInfo territoryInfo, ResourceInfo resourceInfo, DiplomacyInfo diplomacyInfo) {
this.territoryInfo = territoryInfo;
this.resourceInfo = resourceInfo;
this.diplomacyInfo = diplomacyInfo;
}
// ...getters, setters, toString()...
}
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
public class Main {
public static void main(String[] args) throws IOException {
// Create our object
TerritoryInfo territoryInfo = new TerritoryInfo("Spain has 6 provinces, Russia has 10 provinces, France has 8 provinces");
ResourceInfo resourceInfo = new ResourceInfo("Spain has 100 gold, Russia has 80 gold, France has 90 gold");
DiplomacyInfo diplomacyInfo = new DiplomacyInfo("France is at war with Russia, Spain has taken a neutral position");
SavedGame savedGame = new SavedGame(territoryInfo, resourceInfo, diplomacyInfo);
FileOutputStream fileOutputStream = new FileOutputStream("C:\\Users\\Username\\Desktop\\save.ser");
ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
objectOutputStream.writeObject(savedGame);
objectOutputStream.close();
}
}
import java.io.*;
public class Main {
public static void main(String[] args) throws IOException, ClassNotFoundException {
FileInputStream fileInputStream = new FileInputStream("C:\\Users\\Username\\Desktop\\save.ser");
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
SavedGame savedGame = (SavedGame) objectInputStream.readObject();
System.out.println(savedGame);
objectInputStream.close();
}
}
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