java中IO流中的对象操作流（2）——解决对象输入流读取对象出现异常的问题

解决对象输入流读取对象出现异常的问题

package com.itheima_07;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;

/*
 * 解决对象输入流读取对象出现异常的问题
 * 
 */
public class ObjectOutputStreamDemo3 {
	public static void main(String[] args) throws IOException, ClassNotFoundException   {
		//method();
		
		//创建对象输入流的对象
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream("b.txt"));
		//读取数据
		Object obj = ois.readObject(); 
		//System.out.println(obj);
		
		//向下转型，获取具体的子类对象
		ArrayList list = (ArrayList) obj;
		for (Student student : list) {
			System.out.println(student);
		}
		
		//释放资源
		ois.close();
	}

	private static void method() throws IOException, FileNotFoundException {
		//创建对象输出流的对象
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("b.txt"));
		//创建集合对象
		ArrayList list = new ArrayList();
		//添加学生对象
		list.add(new Student("wangwu",30));
		list.add(new Student("zhaoliu",28));
		//写出集合对象
		oos.writeObject(list);
		
		//释放资源
		oos.close();
	}
}

解决读写对象版本不一致问题

package com.itheima_07;

import java.io.Serializable;

public class Student implements Serializable {
	

	/**
	 * 
	 */
	private static final long serialVersionUID = 6361890890437825953L;
	String name;
	int age;
	String gender;

	
	public Student(String name,int age) {
		this.name = name;
		this.age = age;
	}


	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + ", gender=" + gender + "]";
	}
 
}


package com.itheima_07;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/*
 * 解决对实现序列化接口出现的黄色警告问题
 * Exception in thread "main" java.io.InvalidClassException
 * 当 Serialization 运行时检测到某个类具有以下问题之一时，抛出此异常。 
		该类的序列版本号与从流中读取的类描述符的版本号不匹配 
		该类包含未知数据类型 
		该类没有可访问的无参数构造方法 
 * 
 */
public class ObjectOutputStreamDemo4 {
	public static void main(String[] args) throws IOException, ClassNotFoundException  {
		//method();
		
		method2();
	}
	
	//读取学生对象
	private static void method2() throws IOException, FileNotFoundException, ClassNotFoundException {
		//创建对象输入流的对象
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream("c.txt"));
		//读取对象
		Object obj = ois.readObject();
		System.out.println(obj);
		//释放资源
		ois.close();
	}
	
	//写出学生对象
	private static void method() throws IOException, FileNotFoundException {
		//创建对象输出流的对象
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("c.txt"));
		//创建的学生对象
		Student s = new Student("qianqi",28);
		//写出学生对象
		oos.writeObject(s);
		//释放资源
		oos.close();
	}

}