總結一下Java中transient關鍵字的作用:
首先從transient單詞本身的意思來理解,它的英文原意爲:短暫的,暫時的
它的作用體現在將數據序列化的時候,你不想把其中的某個屬性序列化到文件中,就需要用transient修飾,指明該屬性是一個臨時的屬性,舉個例子:
這是一個學生類:
public class Student implements Serializable {//注意:要想序列化,必須實現Serializable接口
private String name;
private Integer age;
private transient String address; //使用transient修飾
public Student() {
}
public Student(String name, Integer age, String address) {
this.name = name;
this.age = age;
this.address = address;
}
//Getter/Setter
}
我序列化的時候不打算將學生的地址這個屬性保存,只想保存name和age屬性,我將adress屬性用transient關鍵字修飾,下面進行序列化:
public class TestStudent {
public static void main(String[] args) throws IOException {
List<Student> list = new ArrayList<>();
Student s1 = new Student("Jack", 20, "北京");
Student s2 = new Student("Rose", 21, "上海");
Student s3 = new Student("Hoke", 22, "深圳");
Student s4 = new Student("Mark", 23, "天津");
Student s5 = new Student("Json", 24, "成都");
list.add(s1);
list.add(s2);
list.add(s3);
list.add(s4);
list.add(s5);
//將學生信息序列化到student.txt文件中
File file = new File("student.txt");
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(list);
}
}
下面進行反序列化,進行驗證transient的作用:
@Test
public void test() throws IOException, ClassNotFoundException {
ObjectInputStream ois = new ObjectInputStream(new FileInputStream(new File("student.txt")));
Object object = ois.readObject();
if (object instanceof List) {
List<Student> list = (List<Student>) object;
list.forEach(System.out::println);
}
}
結果:
可以看到輸出結果中的address屬性值爲null,沒有將值序列化進去;