Java_基础—对象操作流ObjecOutputStream/ObjectInputStream

不念不忘少年蓝@ 2022-06-11 02:54 150阅读 0赞

**创建Person类，属性为name, age. 该类继承接口Serializable**

package com.soar.bean;
    
    import java.io.Serializable;
    
    public class Person implements Serializable{
        
        /**
         * * 注意
         * 要写出的对象必须实现Serializable接口才能被序列化
         * 不用必须加id号
         * 
         * Exception in thread "main" java.io.InvalidClassException: 
         * com.soar.bean.Person; local class incompatible: 
         * stream classdesc serialVersionUID = 1, 
         * local class serialVersionUID = 2
         */
        private static final long serialVersionUID = 2L;
        private String name;
        private int age;
        private String gender;
    
        public Person() {
            super();
    
        }
        public Person(String name, int age) {
            super();
            this.name = name;
            this.age = age;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
        @Override
        public String toString() {
            return "Person [name=" + name + ", age=" + age + "]";
        }
    
    }

**创建ObjectOutputStream类，在e.txt中写出对象**

package com.soar.otherio;
    
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.ObjectOutputStream;
    import java.util.ArrayList;
    
    import com.soar.bean.Person;
    
    public class Demo3_ObjectOutputStream {
        
        /*
    ****** 1.什么是对象操作流
        * 该流可以将一个对象写出, 或者读取一个对象到程序中. 
        * 也就是执行了序列化和反序列化的操作.
    ****** 2.使用方式
        * 写出: new ObjectOutputStream(OutputStream), writeObject()
        * 
        * 序列化：将对象写到文件上
        * 
         */
        public static void main(String[] args) throws IOException {
            //writeObject();
            //对象操作流优化（将对象存储在集合中写出）
            Person p1 = new Person("张三",23);
            Person p2 = new Person("李四",24);
            Person p3 = new Person("王五",25);
            Person p4 = new Person("赵六",26);
    
            ArrayList<Person> list = new ArrayList<>();
            list.add(p1);
            list.add(p2);
            list.add(p3);
            list.add(p4);
    
            ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("e.txt"));
            oos.writeObject(list);          //把整个集合对象一次写出
            oos.close();
    
        }
    
        private static void writeObject() throws IOException, FileNotFoundException {
            Person p1 = new Person("张三",23);
            Person p2 = new Person("李四",24);
    
            ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("e.txt"));
            oos.writeObject(p1);
            oos.writeObject(p2);
    
            oos.close();
        }
    
    }

**创建ObjectInputStream类，将存储在e.txt中的对象，写入**

package com.soar.otherio;
    
    import java.io.FileInputStream;
    import java.io.FileNotFoundException;
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.util.ArrayList;
    
    import com.soar.bean.Person;
    
    public class Demo4_ObjectInputStream {
        
        /*
         * 读取: new ObjectInputStream(InputStream), readObject()
         * ObjectInputStream 
         * 对象输入流，反序列化
         */
        public static void main(String[] args) throws IOException, IOException, ClassNotFoundException {
            //writeObject();
            ObjectInputStream ois = new ObjectInputStream(new FileInputStream("e.txt"));
            ArrayList<Person> list = (ArrayList<Person>) ois.readObject();  //将集合对象一次读取
    
            for (Person person : list) {
                System.out.println(person);
            }
            ois.close();
            /*
             *  Person [name=张三, age=23]
                Person [name=李四, age=24]
                Person [name=王五, age=25]
                Person [name=赵六, age=26]
             */
    
        }
    
        private static void writeObject() throws IOException,
                FileNotFoundException, ClassNotFoundException {
            ObjectInputStream ois = new ObjectInputStream(new FileInputStream("e.txt"));
    
            Person p1 = (Person) ois.readObject();
            Person p2 = (Person) ois.readObject();
            //Person p3 = (Person) ois.readObject();    //EOFException 当文件读取到了末尾时出现EOFException
    
    
            System.out.println(p1);     //Person [name=张三, age=23]
            System.out.println(p2);     //Person [name=李四, age=24]
        }
    
    }