IO之数据流、对象流、打印流！

数据流

    package com.yishan.io3;

    import java.io.*;

    /**
    * 数据流
    * 1.写出后读取
    * 2.读取的顺序与写出保持一致
    *
    * DataOutputStream
    * DataInputStream
    * @author : yishan
    * @date : 2020-09-08 11:27
    */
    public class DataTest {

        public static void main(String[] args) throws IOException {
            //写出
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(baos));
            //操作数据类型+数据
            dos.writeUTF("编程");
            dos.writeInt(56);
            dos.writeChar('a');
            dos.flush();
            byte[] datas = baos.toByteArray();

            //读取
            DataInputStream dis = new DataInputStream(new BufferedInputStream(new ByteArrayInputStream(datas)));
            String msg = dis.readUTF();
            int aa = dis.readInt();
            char bb = dis.readChar();
            System.out.println(aa);
        }

    }

对象流（序列化和反序列化）

• 1.先写出后读取

• 2.读取的顺序和写出的顺序保持一致

• 3.不是所有的对象都可以实现序列化，必须实现Serialization接口

    package com.yishan.io3;
  

    import javax.xml.crypto.Data;
    import java.io.*;
    import java.util.Date;

    /**
    * 对象流
    * 1.写出后读取
    * 2.读取的顺序与写出保持一致
    * 3.不是所有的对象都可以序列化Serializable
    *
    * ObjectOutputStream
    * ObjectInputStream
    * @author : yishan
    * @date : 2020-09-08 11:27
    */
    public class ObjectTest {

        public static void main(String[] args) throws IOException, ClassNotFoundException {
            //写出 -- 序列化
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(new BufferedOutputStream(baos));
            //操作数据类型+数据
            oos.writeUTF("编程");
            oos.writeInt(56);
            oos.writeChar('a');
            //加入对象
            oos.writeObject("编程思想！");
            oos.writeObject(new Date());
            Employee emp = new Employee("马云",400);
            oos.writeObject(emp);
            oos.flush();
            byte[] datas = baos.toByteArray();

            //读取--反序列化
            ObjectInputStream ois = new ObjectInputStream(new BufferedInputStream(new ByteArrayInputStream(datas)));
            String msg = ois.readUTF();
            int aa = ois.readInt();
            char bb = ois.readChar();
            System.out.println(aa);
            Object str = ois.readObject();
            Object data = ois.readObject();
            Object employee = ois.readObject();

            if (str instanceof String){
                String strObj = (String)str;
                System.out.println(strObj);
            }
            if (data instanceof Data){
                Data dataObj = (Data)data;
                System.out.println(dataObj);
            }
            if (employee instanceof Employee){
                Employee empObj = (Employee)employee;
                System.out.println(empObj.getName()+"--"+((Employee) employee).getSalary());
            }
        }

    }

    //javaBean   封装数据
    class Employee implements java.io.Serializable{
        private transient String name;//该数据不需要序列化
        private double salary;

        public Employee(){
        }

        public Employee(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;
        }
    }

打印流 PrintStream

    package com.yishan.io3;

    import java.io.*;

    /**
    * 打印流  PrintStream
    * @author : yishan
    * @date : 2020-09-15 13:44
    */
    public class PrintTest01 {
        public static void main(String[] args) throws FileNotFoundException {
            //打印流 System.out
            PrintStream ps = System.out;
            ps.println("打印流");
            ps.println(true);

            ps = new PrintStream(new BufferedOutputStream(new FileOutputStream("print.txt")),true);
            ps.println("打印流");
            ps.println(true);
            ps.close();
            //重定向输出端
            System.setOut(ps);
            System.out.println("change!");
            //重定向回控制台
            System.setOut(new PrintStream(new BufferedOutputStream(new FileOutputStream(FileDescriptor.out)),true));
            System.out.println("back!");
        }
    }

打印流 PrintWriter

    package com.yishan.io3;

    import java.io.*;

    /**
    * 打印流  PrintWriter
    * @author : yishan
    * @date : 2020-09-15 13:44
    */
    public class PrintTest02 {
        public static void main(String[] args) throws FileNotFoundException {

            PrintWriter pw = new PrintWriter(new BufferedOutputStream(new FileOutputStream("print.txt")), true);
            pw.println("打印流");
            pw.println(true);
            pw.close();
        }
    }

赏

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