Shulou(Shulou.com)06/02 Report--

This article focuses on "how to use object flow and serialization in Java". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor learn how to use object flow and serialization in Java.

It looks pretty simple, so take a look at the following example:

Public class Student {

Private int id

Private String name

Private String sex

Private String tel

/ / getter,setter is omitted here

Public Student (int id, String name, String sex, String tel) {

Super ()

This.id = id

This.name = name

This.sex = sex

This.tel = tel

}

}

Public class TestObjectStream {

Public static void main (String [] args) {

WriteObject ()

ReadObject ()

}

Public static void writeObject () {

Try {

FileOutputStream fos = newFileOutputStream ("C:/Users/wangliang/Desktop/1")

ObjectOutputStream oos = new ObjectOutputStream (fos)

Student student1 = new Student (1, "Mary", "female", "11111")

Student student2 = new Student (2, "Jack", "male", "2222")

Student student3 = new Student (3, "Andy", "male", "3333")

List list = Arrays.asList (student1, student2, student3)

Oos.writeObject (list); / / write object

Oos.flush ()

Fos.close ()

Oos.close ()

} catch (Exception e) {

E.printStackTrace ()

}

}

Public static void readObject () {

Try {

FileInputStream fis = new FileInputStream ("C:/Users/wangliang/Desktop/1")

ObjectInputStream ois = new ObjectInputStream (fis)

List list = (List) ois.readObject (); / / read the object

List.forEach (System.out::println)

Fis.close ()

Ois.close ()

} catch (Exception e) {

E.printStackTrace ()

}

}

}

Then the following exception is found during the running process:

Java.io.NotSerializableException: com.qianfeng.day33.entity.Student

At java.io.ObjectOutputStream.writeObject0 (ObjectOutputStream.java:1184)

At java.io.ObjectOutputStream.writeArray (ObjectOutputStream.java:1378)

At java.io.ObjectOutputStream.writeObject0 (ObjectOutputStream.java:1174)

At java.io.ObjectOutputStream.defaultWriteFields (ObjectOutputStream.java:1548)

At java.io.ObjectOutputStream.writeSerialData (ObjectOutputStream.java:1509)

At java.io.ObjectOutputStream.writeOrdinaryObject (ObjectOutputStream.java:1432)

At java.io.ObjectOutputStream.writeObject0 (ObjectOutputStream.java:1178)

At java.io.ObjectOutputStream.writeObject (ObjectOutputStream.java:348)

At com.qianfeng.day33.test.TestObjectStream.writeObject (TestObjectStream.java:28)

At com.qianfeng.day33.test.TestObjectStream.main (TestObjectStream.java:16)

According to the description of this exception, the entity class is not serialized, plus the serialized code to try, as follows:

Public class Student implements java.io.Serializable {

Private static final long serialVersionUID = 4500674287188895027L

Private int id

Private String name

Private String sex

Private String tel

/ / getter,setter is omitted here

Public Student (int id, String name, String sex, String tel) {

Super ()

This.id = id

This.name = name

This.sex = sex

This.tel = tel

}

}

Just implement a java.io.Serializable interface, but take a look at the description of the interface source code:

*

* @ author unascribed

* @ see java.io.ObjectOutputStream

* @ see java.io.ObjectInputStream

* @ see java.io.ObjectOutput

* @ see java.io.ObjectInput

* @ see java.io.Externalizable

* @ since JDK1.1

, /

Public interface Serializable {

}

It is found that there is nothing in the interface. @ see in the above description is almost followed by some operations on the object stream, indicating that the role of serialization is related to the object flow, so what does serialization do?

We can look at the serialization requirements in other languages by analogy, such as the requirements in OC as follows:

/ / data of the stream (JSON data)-> OC object

+ (id) JSONObjectWithData: (NSData *) data options: (NSJSONReadingOptions) opt error: (NSError * *) error

/ / OC object-> data of the stream (Json data)

+ (NSData *) dataWithJSONObject: (id) obj options: (NSJSONWritingOptions) opt error: (NSError * *) error

In OC, if an entity class needs to be serialized, you must implement these two methods. The purpose of these two methods is to tell the system how to convert the entity class to a JSON data (specify key and value) when you need to stream or save the entity class to a file, and then convert it to binary (byte array) using strings.

So why not need it in Java? Because there is a reflection mechanism in Java, this can be done easily.

So what is the role of serial numbers in serialization? Is to ensure that serialization and deserialization can be done correctly, and the conversion can be successful only if the sequence numbers are the same.

At this point, I believe you have a deeper understanding of "object flow and serialization in Java". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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