java對象執行個體化的方式

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java對象執行個體化的方式有以下幾種：
1、使用new
2、原廠模式
3、反射
4、clone()方法
5、還原序列化方式

/**

• 實現Cloneable和Serializable介面

• */
  public class Book implements Cloneable, Serializable {
  private static final long serialVersionUID = 1L;

  private Integer serialNum; // 序號
  private String name; // 圖書名稱

  public Book() {
  System.out.println("預設建構函式");
  }

  public Book(Integer serialNum, String name) {
  System.out.println("帶參數建構函式");
  this.serialNum = serialNum;
  this.name = name;
  }

  public int getSerialNum() {
  return serialNum;
  }
  public void setSerialNum(int serialNum) {
  this.serialNum = serialNum;
  }
  public String getName() {
  return name;
  }
  public void setName(String name) {
  this.name = name;
  }

  @Override
  public String toString() {
  if (name == null) {
  return "書籍屬性還未填寫";
  }

  return serialNum + " : " + name;

  }

  @Override
  protected Object clone() throws CloneNotSupportedException {
  return super.clone();
  }
  }

class BookFactory {
public static Book getInstance(Integer serialNum, String name) {
return new Book(serialNum, name);
}
}

public class Instantiation {

// 1.通過new執行個體化對象public static Book newMode() {    System.out.println("============================================================");    System.out.println("通過new執行個體化對象");    Book book = new Book(1, "大道揚帆");    return book;}// 2.通過工廠方式執行個體化對象，其本質還是new，但將執行個體化的細節交給了工廠來處理，屏蔽了和業務代碼無關的功能，一定程度上實現了和業務代碼的解耦public static Book factoryMode() {    System.out.println("============================================================");    System.out.println("通過工廠方式執行個體化對象");    return BookFactory.getInstance(2, "大道揚帆");}// 3.通過反射方式執行個體化對象@SuppressWarnings("rawtypes")public static Book reflectMode() throws Exception {    System.out.println("============================================================");    System.out.println("通過反射方式執行個體化對象");    Class[] parameterTypes = new Class[] {Integer.class, String.class};    Constructor constructor = Book.class.getConstructor(parameterTypes);    Book book = (Book) constructor.newInstance(3, "大道揚帆");    return book;}// 3-1.通過反射方式執行個體化對象還有一種方式，但本質上其實和上面的一樣,但需要類本身有無參建構函式public static Book reflectAnotherMode() throws Exception {    System.out.println("============================================================");    System.out.println("通過反射方式執行個體化對象的另外一種方式");    Book book = (Book) Class.forName("instantiation.Book").newInstance();    return book;}// 4.調用已存在對象的clone()方法執行個體化對象public static Book cloneMode(Book book) throws Exception {    System.out.println("============================================================");    System.out.println("調用已存在對象的clone()方法執行個體化對象");    Book newBook = (Book) book.clone();    System.out.println("原對象和複製對象是同一個對象嗎？" + (book == newBook));    return newBook;}// 5.對象序列化後可以通過還原序列化建立對象public static Book unSerializedMode() throws Exception {    System.out.println("============================================================");    System.out.println("對象序列化後可以通過還原序列化建立對象");    Book book = new Book(5, "大道揚帆");    ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(new File("D:/book.obj")));    objectOutputStream.writeObject(book);    ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(new File("D:/book.obj")));    Book newBook = (Book) objectInputStream.readObject();    System.out.println("原對象和還原序列化的對象是同一個嗎？" + (book == newBook));    return newBook;}public static void main(String[] args) throws Exception {    System.out.println(Instantiation.newMode());    System.out.println(Instantiation.factoryMode());    System.out.println(Instantiation.reflectMode());    System.out.println(Instantiation.reflectAnotherMode());    Book book = new Book(4, "大道揚帆");    System.out.println(Instantiation.cloneMode(book));    System.out.println(Instantiation.unSerializedMode());}

}

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java對象執行個體化的方式