一、序列化：ObjectOutputStream

直接按照下面的方式写的话会报异常，原因是被序列化的类需要实现 **Serializable** 这个接口

类可以被序列化的条件：

  1. **实现 **`**Serializable**`** 这个接口**
  2. **属性中需要包含 **_**serialVersionUID **_
  3. **内部属性也要都是可序列化的**

补充：

  1. **不可以序列化 **`static` 或者 `transient` **修饰的成员变量**

package test20;
import jdk.nashorn.internal.objects.annotations.Getter;
import org.junit.Test;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
/**
 * Created By Intellij IDEA
 *
 * @author Xinrui Yu
 * @date 2021/12/5 17:17 星期日
 */
public class ObjectOutputStreamTest {
    @Test
    public void objectOutputStreamTest(){
        ObjectOutputStream objectOutputStream = null;
        FileOutputStream fileOutputStream = null;
        Student student = new Student(1, "yxr", "男");
        try{
            fileOutputStream = new FileOutputStream("objectOutputStreamTest.txt");
            objectOutputStream = new ObjectOutputStream(fileOutputStream);
            objectOutputStream.writeObject(student);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if(objectOutputStream != null){
                try {
                    objectOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}
class Student{
    private Integer id;
    private String name;
    private String gender;
    public Student() {
    }
    public Student(Integer id, String name, String gender) {
        this.id = id;
        this.name = name;
        this.gender = gender;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                '}';
    }
}

修改完成之后，运行：
可以得到一个看不懂的二进制文件
可以从这个二进制文件，使用反序列化方法来得到我们存进去的对象

二、反序列化：ObjectInputStream

可以通过反序列化，将上面存储的二进制文件变成一个程序中的一个对象

package test20;
import org.junit.Test;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
/**
 * Created By Intellij IDEA
 *
 * @author Xinrui Yu
 * @date 2021/12/5 17:57 星期日
 */
public class ObjectInputStreamTest {
    @Test
    public void objectInputStreamTest(){
        FileInputStream fileInputStream = null;
        ObjectInputStream objectInputStream = null;
        try{
            fileInputStream = new FileInputStream("objectOutputStreamTest.txt");
            objectInputStream = new ObjectInputStream(fileInputStream);
            Object object = objectInputStream.readObject();
            if(object instanceof Student){
                Student student = (Student) object;
                System.out.println("id:" + student.getId());
                System.out.println("name:" + student.getName());
                System.out.println("gender:" + student.getGender());
            }else{
                throw new RuntimeException("反序列化失败");
            }
        }catch (IOException | ClassNotFoundException e){
            e.printStackTrace();
        } finally {
            if (objectInputStream != null) {
                try {
                    objectInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

运行，可以看到成功反序列化出来了一个 Student 对象<br />![image.png](https://cdn.nlark.com/yuque/0/2021/png/21436600/1638698774611-a547412c-930c-49c8-b0e1-e39698ab1952.png#clientId=u1bab84b0-9cd8-4&from=paste&id=udddd1809&originHeight=321&originWidth=1167&originalType=binary&ratio=1&size=372545&status=done&style=none&taskId=u48a04bc0-9e63-4158-804c-7de4afb1db6)