IO流之对象专属流

单个对象

以下代码把一个Java对象从内存中写入到硬盘，再读回到内存：

package com.javalearn.io.ObjectIO; 
 
import java.io.*; 
 
public class TestForObjIO { 
    public static void main(String[] args) throws Exception{ 
        Student s = new Student(1111,"cxf"); 
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("file1")); 
        oos.writeObject(s);  // 序列化 
        oos.flush(); 
        oos.close(); 
 
        ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("file1")); 
        Object obj = objectInputStream.readObject();  // 反序列化 
        System.out.println(obj);  // 自动执行toString方法 
        objectInputStream.close(); 
    } 
} 
 
class Student implements Serializable {  // 实现Serializable接口，才能序列化 
    private int no;  // 若加上transient关键字，则此属性不参与序列化，反序列化时显示null 
    private String name; 
    public Student() { 
 
    } 
    public Student(int no,String name) { 
        this.no = no; 
        this.name = name; 
    } 
 
    public int getNo() { 
        return no; 
    } 
 
    public void setNo(int no) { 
        this.no = no; 
    } 
 
    public String getName() { 
        return name; 
    } 
 
    public void setName(String name) { 
        this.name = name; 
    } 
 
    @Override 
    public String toString() { 
        return "Student{" + 
                "no=" + no + 
                ", name='" + name + '\'' + 
                '}'; 
    } 
} 

输出结果：

Student{no=1111, name='cxf'} 

多个对象

以下代码进行多个对象的IO：

package com.javalearn.io.objIOset; 
 
import java.io.*; 
import java.util.ArrayList; 
import java.util.List; 
 
public class TestForMultiObj { 
    public static void main(String[] args) throws Exception{ 
        List<User> userList = new ArrayList<>();  // 用集合装载对象 
        userList.add(new User(1,"cxf")); 
        userList.add(new User(2,"smf")); 
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("file1")); 
        oos.writeObject(userList);  // 把集合序列化 
        oos.flush(); 
        oos.close(); 
        ObjectInputStream ois  =new ObjectInputStream(new FileInputStream("file1")); 
        List<User> userList1 = (List<User>) ois.readObject();  // 反序列化 
        for(User user:userList1) { 
            System.out.println(user); 
        } 
        ois.close(); 
    } 
} 
 
class User implements Serializable { 
    private int no; 
    private String name; 
 
    public User() { 
    } 
 
    public User(int no, String name) { 
        this.no = no; 
        this.name = name; 
    } 
 
    @Override 
    public String toString() { 
        return "User{" + 
                "no=" + no + 
                ", name='" + name + '\'' + 
                '}'; 
    } 
} 

输出结果：

User{no=1, name='cxf'} 
User{no=2, name='smf'}