transient

transient是型別修飾符，只能用來修飾字段。在物件序列化的過程中，標記為transient的變數不會被序列化。

序列化和反序列化

一個物件的表示轉化為位元組流的過程稱為序列化(serialization)，從位元組流中把物件重建出來稱為反序列化反序列化(deserialization）。

測試程式碼

public class TestTransient {

  /**
   * @param args
   * @throws IOException
   * @throws FileNotFoundException
   * @throws ClassNotFoundException
   */
 

  public static void main(String[] args) throws IOException, ClassNotFoundException {
    A a = new A(25, "測試");
    System.out.println(a);
    ObjectOutputStream oos =
        new ObjectOutputStream(new FileOutputStream("/Users/dev/Desktop/tmp/a.txt"));
    oos.writeObject(a);
    oos.close();
    ObjectInputStream ois =
        new
 
 ObjectInputStream(new FileInputStream("/Users/dev/Desktop/tmp/a.txt"));
    a = (A) ois.readObject();
    System.out.println(a);

  }

  static class A implements Serializable {
    int a;
    transient String b;

    public A(int a, String b) {
      this.a = a;
      this.b = b;
    }

    public String toString
 
() {
      return "a = " + a + ",b = " + b;
    }
  }

}

輸出結構

a = 25,b = 測試
a = 25,b = null