java使用IO对象流进行数据读写

对象的读写
  使用ObjectInputStream和ObjectOutputStream读写对象(序列化与反序列化)。

只有字节流没有字符流

1）.类必须实现Serializable接口
2).给类加个序列化编号，给类定义一个标记，新的修改后的类还可以操作曾经序列化的对象
3).静态是不能被序列化的，序列化只能对堆中的进行序列化 ，不能对“方法区”中的进行序列化
4).不需要序列化的字段前加 transient

小例子：

先创建一个Dog对象并序列化:

package com.uwo9.test03;

import java.io.Serializable;

public class Dog implements Serializable {
	private static final long serialVersionUID = 2809685095868158625L;
	String name;
	String color;
}

再创建一个Student对象并序列化：

package com.uwo9.test03;

import java.io.Serializable;

public class Student implements Serializable {
	private static final long serialVersionUID = 9078616504949971001L;
	static public  String schoolName;
	private transient String name;
	private transient int age;
	private double score;
	private Dog dog;
	public Student() {
		super();
	}
	public Student(String name, int age, double score, Dog dog) {
		super();
		this.name = name;
		this.age = age;
		this.score = score;
		this.dog = dog;
	}
	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;
	}
	public double getScore() {
		return score;
	}
	public void setScore(double score) {
		this.score = score;
	}
	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + ", score=" + score + "]";
	}

}

将数据写入对象流并存入文件

package com.uwo9.test03;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Collections;

public class Test01 {

	public static void main(String[] args) {
		Dog dog = new Dog();
		dog.name = "大黄";
		dog.color = "Yellow";
		Student student1 = new Student("学生1", 18, 99,dog);
		Student student2 = new Student("学生2", 19, 99,dog);
		Student student3 = new Student("学生3", 20, 99,dog);
		Student.schoolName = "某某大学";
		File file = new File("E:/Temp/Test1.txt");
		ObjectOutputStream oos = null;
		try {
			oos = new ObjectOutputStream(new FileOutputStream(file));
			//oos.writeObject(student);
			ArrayList arrayList = new ArrayList<>();
			Collections.addAll(arrayList, student1,student2,student3);
			oos.writeObject(arrayList);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			try {
				oos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		
	}

}

从指定文件中读取对象

package com.uwo9.test03;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.ArrayList;

public class Test02 {

	public static void main(String[] args) {
		// 从指定的文件中读取对象
		File file = new File("E:/Temp/Test1.txt");
		ObjectInputStream ois=null;
		try {
			ois = new ObjectInputStream(new FileInputStream(file));
			// 读取对象
			// Student stu = (Student)ois.readObject();
			// System.out.println("读取到的数据为:"+stu);
			@SuppressWarnings("unchecked")
			ArrayList arrayList = (ArrayList) ois.readObject();
			for (Student student : arrayList) {
				System.out.println(student);
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}finally {
			try {
				ois.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

	}

}