io流的学习4

news2024/9/25 11:17:45

字符缓冲流

原理：底层自带了长度为8192的缓冲区提高性能。

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class BufferedStringdemo01 {
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new FileReader("F:\\javaEE\\src\\MyCharset\\a.txt"));
        /*String s = br.readLine();
        System.out.println(s);*/
        String line;
        while((line=br.readLine())!=null){
            System.out.println(line);
        }
        br.close();
    }
}

package MyCharset;

import java.io.*;

public class BufferedStringdemo02 {
    public static void main(String[] args) throws IOException {
        BufferedWriter bw=new BufferedWriter(new FileWriter("F:\\javaEE\\src\\MyCharset\\a.txt"));
        bw.write("hhhhhhhh");
        bw.newLine();
        bw.write("aaaaaaa");
        bw.newLine();
        bw.close();
    }
}

转换流

是字符流和字节流之间的桥梁。

package myConvertstream;

import java.io.*;

public class mydemo01 {
    public static void main(String[] args) throws IOException {
        InputStreamReader isr=new InputStreamReader(new FileInputStream("myio\\gbkfile.txt"),"GBK") ;
   int ch;
   while((ch=isr.read())!=-1){
       System.out.println((char)ch);
   }
   isr.close();
    }
}

package myConvertstream;

import java.io.*;
import java.nio.charset.Charset;

public class mydemo01 {
    public static void main(String[] args) throws IOException {
/*   int ch;
   while((ch=isr.read())!=-1){
       System.out.println((char)ch);
   }
   isr.close();*/
        FileReader fr=new FileReader("myio\\gbkfile.txt", Charset.forName("GBK"));
        int ch;
        while((ch=fr.read())!=-1){
            System.out.println((char)ch);
        }
        fr.close();
    }
}

package myConvertstream;

import java.io.*;

public class mcdemo01 {
    public static void main(String[] args) throws IOException {
        OutputStreamWriter osw=new OutputStreamWriter(new FileOutputStream("myio\\b.txt"),"GBK");
    osw.write("hellohello");
    osw.close();
    }
}

package myConvertstream;

import java.io.*;

public class mcdemo02 {
    public static void main(String[] args) throws IOException {
        /*将本地GBK文件转换成UTF-8*/
        //jdk11以前的方案
        InputStreamReader isr=new InputStreamReader(new FileInputStream("myio\\b.txt"),"GBK");
        OutputStreamWriter osw=new OutputStreamWriter(new FileOutputStream("myio\\d.txt"),"UTF-8");
        int b;
        while((b=isr.read())!=-1){
            osw.write(b);
        }
        osw.close();
        isr.close();
    }
}

package myConvertstream;

import java.io.*;

public class mcdemo03 {
    public static void main(String[] args) throws IOException {
        /*利用字节流读取文件中的数据，每次读一整行，而且不能出现乱码*/
        FileInputStream fis=new FileInputStream("myio\\a.txt");
        InputStreamReader isr=new InputStreamReader(fis);
        BufferedReader br=new BufferedReader(isr);
        String s = br.readLine();
        System.out.println(s);
        br.close();
    }
}

序列化流

可以把JAVA中的对象写到本地文件中。

import java.io.Serializable;

public class Student implements Serializable {
    private int age;
    private String name;

    public Student() {
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Student{" +
                "age=" + age +
                ", name='" + name + '\'' +
                '}';
    }
}

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

public class odemo01 {
    public static void main(String[] args) throws IOException {
Student stu=new Student(24,"karry");
        ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("myio\\a.txt"));
        oos.writeObject(stu);
        oos.close();

    }
}

反序列化流

可以把序列化到本地文件中的对象，读取到程序中来。

package myConvertstream;

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

public class odemo02 {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        ObjectInputStream ois=new ObjectInputStream(new FileInputStream("myio\\a.txt"));
        Object o = ois.readObject();
        System.out.println(o);
        ois.close();
    }
}