java_io_对象流,能够保存基本数据类型和对象

  • ObjectInputStream(字节流) 和ObjectOutputStream(字节流)
  • 除了保存基本数据类型,还包括自定义的对象,自定义的对象读取后类型是Object,使用需要强制转换
  • 序列化:输出流,
  • 反序列化:输入流
  • 和数据流一致,必须先写出后读取,读取和写出顺序保持一致
  • 序列化的对象必须实现java.io.Serializable接口
  • transient:该数据不需要序列化,数据透明(输出显示null),private transient String name;

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    //写出后读取,读取的数徐与写出保持一致

    public class n {
    
    public static void main(String[]args) throws IOException, ClassNotFoundException
    {

    写入字节数组
    //写出 序列化
    ByteArrayOutputStream os=new ByteArrayOutputStream();
    ObjectOutputStream oos=new ObjectOutputStream(new BufferedOutputStream(os));
    ha ff=new ha("hh",222);

    oos.writeUTF("哈哈");
    oos.writeChar('q');
    oos.writeBoolean(false);
    
    oos.writeObject(ff);
    oos.flush();
    byte[] datas=os.toByteArray();
    oos.close();
    //读取 反序列化
    ObjectInputStream ois =new ObjectInputStream(new BufferedInputStream(new ByteArrayInputStream(datas)));
    String s=ois.readUTF();
    char ch=ois.readChar();
    boolean flag=ois.readBoolean(); 
    Object str=ois.readObject();  //Object需要强制转换
    
    //还原(判断是哪个类,然后强制转换):
    if (str instanceof String ) //是String类就直接转换成字符串
    {
        String s1=(String)str;
        System.out.println(s1);
    }
    if(str instanceof Data)
    {
        Date d=(Date)str;
        System.out.println(d);
    }
    if(str instanceof ha)
    {
        ha fr=(ha)str;
        System.out.println(fr.getName()+fr.getSalary());
    }
    ois.close();
    }
    
    //javabean,用于封装数据   
    class ha implements java.io.Serializable  {
    
    private transient String name;  //该数据不需要序列化,数据透明
    private double salary;
    
    public ha()
        {
    
    }
    
    public ha(String name,double salary)
    {
    this.name=name;
    this.salary=salary;
    }
    
    public String getName() {
    return name;
    }
    
    public void setName(String name) {
    this.name = name;
    }
    
    public double getSalary() {
    return salary;
    }
    
    public void setSalary(double salary) {
    this.salary = salary;
    }
    
    }

写入文件:

      ObjectOutputStream oos=new ObjectOutputStream(new  BufferedOutputStream(new FileOutputStream("D:/d/s")));
        ha ff=new ha("hh",222);
        oos.writeUTF("what");
        oos.writeObject(ff);
        oos.flush();
        oos.close();

    //使用时,反序列化对象

    ObjectInputStream  ois=new ObjectInputStream(new BufferedInputStream(new FileInputStream("D:/d/s")));
    String s=ois.readUTF();
    Object it=ois.readObject();

    if(it instanceof ha)
    {
        ha q=(ha)it;
        System.out.println(q.getName()+q.getSalary());
    }
    ois.close();

    //javabean 用于封装数据
class ha implements java.io.Serializable  {

private transient String name;  //该数据不需要序列化,数据透明
private double salary;

public ha()
{

}

public ha(String name,double salary)
{
    this.name=name;
    this.salary=salary;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public double getSalary() {
    return salary;
}

public void setSalary(double salary) {
    this.salary = salary;
}

}

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