transient关键字详解

作用

1,一旦变量被transient修饰,变量将不再是对象持久化的一部分,该变量内容在序列化后无法获得访问。 
2,transient关键字只能修饰变量,而不能修饰方法和类。注意,本地变量是不能被transient关键字修饰的。变量如果是用户自定义类变量,则该类需要实现Serializable接口。 
3,一个静态变量不管是否被transient修饰,均不能被序列化。

请看代码

//实体类(必须实现Serializable接口,才能被序列化)
public class Resume implements Cloneable,Serializable{
private static final long serialVersionUID = 1L; private String name;
private static String sex;
transient private String age;
private WorkExperience workExperience; public WorkExperience getWorkExperience() {
return workExperience;
} public void setWorkExperience(WorkExperience workExperience) {
this.workExperience = workExperience;
} public String getName() {
return name;
} public void setName(String name) {
this.name = name;
} public String getSex() {
return sex;
} public void setSex(String sex) {
this.sex = sex;
} public String getAge() {
return age;
} public void setAge(String age) {
this.age = age;
} public void dispaly(){
System.out.println("姓名:"+name+"\t年龄:"+age+"\t性别:"+sex);
// System.out.println("工作经历:"+workExperience.getWorkDate()+"\t"+workExperience.getCompany());
} public Object clone(){
try {
Resume resume = (Resume)super.clone();
return resume;
}catch (Exception e){
return null;
} } } public class MainTest2 {
public static void main(String[] args){ try {
// 序列化Resume
Resume resume = new Resume();
resume.setName("哈哈");
resume.setSex("男");
resume.setAge("20");
resume.dispaly();
ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("D:\\resume.txt"));
outputStream.writeObject(resume);
outputStream.close();
}catch (Exception e){
e.printStackTrace();
} }
}
//输出结果
姓名:哈哈 年龄:20 性别:男

反序列化

public class MainTest2 {
public static void main(String[] args){ try {
// 序列化Resume
Resume resume = new Resume();
// resume.setName("哈哈");
// resume.setSex("男");
// resume.setAge("20");
// resume.dispaly();
// ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("D:\\resume.txt"));
// outputStream.writeObject(resume);
// outputStream.close(); //改变sex(根据结果可见sex未被序列化,而是直接从内存中读取)
resume.setSex("女"); //反序列化
ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("D:\\resume.txt"));
Resume resume1 = (Resume) inputStream.readObject();
resume1.dispaly();
}catch (Exception e){
e.printStackTrace();
} }
}
//结果
姓名:哈哈 年龄:null 性别:女

 根据结果可知age字段被transient修饰未能序列化成功,而sex反序列化之前改变了值,所以标明也未被序列化。

  

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