Java中关键字transient的大白话简介说明

transient关键字的功能

被修饰的成员属性变量不被序列化
 即不被序列化

transient关键字的使用场景:
  1.类中的字段值可以根据其它字段推导出来
     如:
	  一个数的和由两个字段组成,那么数字的和，则无需序列化
  2.指定无需序列化的字段

transient关键字的示例

package com.java265;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
class Rectangle implements Serializable{
 
    private static final long serialVersionUID = 1710022455003682613L;
    private Integer width;
    private Integer height;
    private transient Integer area;



    public Rectangle (Integer width, Integer height){
        this.width = width;
        this.height = height;
        this.area = width * height;
    }

    public void setArea(){
        this.area = this.width * this.height;
    }

    @Override
    public String toString(){
        StringBuffer sb = new StringBuffer(40);
        sb.append("width : ");
        sb.append(this.width);
        sb.append("\nheight : ");
        sb.append(this.height);
        sb.append("\narea : ");
        sb.append(this.area);
        return sb.toString();
    }
}

public class TransientExample{
    public static void main(String args[]) throws Exception {
        Rectangle rectangle = new Rectangle(3,4);
        System.out.println("1.原始对象\n"+rectangle);
        ObjectOutputStream o = new ObjectOutputStream(new FileOutputStream("rectangle"));
        // 往流写入对象
        o.writeObject(rectangle);
        o.close();

        // 从流读取对象
        ObjectInputStream in = new ObjectInputStream(new FileInputStream("rectangle"));
        Rectangle rectangle1 = (Rectangle)in.readObject();
        System.out.println("2.反序列化后的对象\n"+rectangle1);
        rectangle1.setArea();
        System.out.println("3.恢复成原始对象\n"+rectangle1);
        in.close();
    }
}