你好！在今天的課程中，我們將討論 Java 中的序列化和反序列化。我們將從一個簡單的例子開始。假設您是一名電腦遊戲開發人員。如果你在 90 年代長大並記得那個時代的遊戲機，你可能知道他們缺少我們今天認為理所當然的東西——保存和加載遊戲的能力 :) 如果沒有，想像一下！![Java 中的序列化和反序列化 - 1]()
恐怕今天沒有這些能力的遊戲就完蛋了！無論如何，“保存”和“加載”遊戲是什麼意思？好吧，我們理解日常含義：我們想從我們離開的地方繼續遊戲。為此，我們創建了一個稍後用於加載遊戲的特定“檢查點”。但這對程序員而不是休閒遊戲玩家意味著什麼？答案很簡單：我們保存程序的狀態。假設您在一款戰略遊戲中玩西班牙。您的遊戲具有狀態：每個人擁有哪些領土，每個人擁有多少資源，存在哪些聯盟以及與誰結盟，誰處於戰爭狀態，等等。這些信息，即我們程序的狀態，必須以某種方式保存，以便恢復數據並繼續遊戲。當它發生的時候， Java 中的序列化是將對象的狀態保存為字節序列的過程。 Java 中的反序列化是從這些字節中恢復對象的過程。任何 Java 對像都可以轉換為字節序列。我們為什麼需要這個？我們一再說過，程序本身並不存在。大多數情況下，它們會相互交互、交換數據等。字節格式對此既方便又高效。例如，我們可以轉換SavedGame的一個對象class 轉換成字節序列，通過網絡將這些字節傳輸到另一台計算機，然後在另一台計算機上將這些字節轉換回 Java 對象！聽起來很難吧？似乎很難讓這一切發生：/幸運的是，事實並非如此！:) 在Java中，Serializable接口負責序列化過程。這個接口非常簡單：您不必實現一個方法就可以使用它！看看我們保存遊戲的類是多麼簡單：
![Java university]()
![Java 中的序列化和反序列化 - 2]()
在 Java 中，這類問題是通過transient關鍵字解決的。如果將此關鍵字添加到類的某個字段，則該字段不會被序列化。讓我們嘗試使我們的SavedGame類的字段之一成為瞬態，然後我們將序列化並恢復單個對象。
![Java webinar]()
恐怕今天沒有這些能力的遊戲就完蛋了！無論如何，“保存”和“加載”遊戲是什麼意思？好吧，我們理解日常含義：我們想從我們離開的地方繼續遊戲。為此，我們創建了一個稍後用於加載遊戲的特定“檢查點”。但這對程序員而不是休閒遊戲玩家意味著什麼？答案很簡單：我們保存程序的狀態。假設您在一款戰略遊戲中玩西班牙。您的遊戲具有狀態：每個人擁有哪些領土，每個人擁有多少資源，存在哪些聯盟以及與誰結盟，誰處於戰爭狀態，等等。這些信息，即我們程序的狀態，必須以某種方式保存，以便恢復數據並繼續遊戲。當它發生的時候， Java 中的序列化是將對象的狀態保存為字節序列的過程。 Java 中的反序列化是從這些字節中恢復對象的過程。任何 Java 對像都可以轉換為字節序列。我們為什麼需要這個？我們一再說過，程序本身並不存在。大多數情況下，它們會相互交互、交換數據等。字節格式對此既方便又高效。例如，我們可以轉換SavedGame的一個對象class 轉換成字節序列，通過網絡將這些字節傳輸到另一台計算機，然後在另一台計算機上將這些字節轉換回 Java 對象！聽起來很難吧？似乎很難讓這一切發生：/幸運的是，事實並非如此！:) 在Java中，Serializable接口負責序列化過程。這個接口非常簡單：您不必實現一個方法就可以使用它！看看我們保存遊戲的類是多麼簡單：
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，這類問題是通過transient關鍵字解決的。如果將此關鍵字添加到類的某個字段，則該字段不會被序列化。讓我們嘗試使我們的SavedGame類的字段之一成為瞬態，然後我們將序列化並恢復單個對象。
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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