Java--IO流

最新推荐文章于 2021-07-16 22:20:26 发布

原创最新推荐文章于 2021-07-16 22:20:26 发布 · 237 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#java #IO流

JAVA基础专栏收录该内容

11 篇文章

订阅专栏

本文深入讲解Java中的IO流概念，包括其分类、字节流与字符流的区别，以及如何使用不同类型的流进行文件操作。通过具体示例展示了字节流和字符流的复制过程，并解释了如何将字节流转换为字符流。

文章目录

IO流概述

IO流用来处理设备之间的数据传输
Java对数据的操作是通过流的方式

IO流的分类

按数据流向
输入流：读入数据
输出流：写出数据
按数据类型
字节流：可传输任意类型的文件
字符流：适合传输文本类型的文件

常用IO流关系图

IO流

字节流的复制文件操作

FileInputStream & FileOutputStream

    @Test
    public void test1() throws IOException {
        InputStream in = new FileInputStream("D:/QQWhatsnew.txt");

        OutputStream out = new FileOutputStream("out.txt");

        byte[] bytes = new byte[1024];
        int len;
        while ((len=in.read(bytes))!=-1){
            out.write(bytes,0,len);
        }
        
        out.close();
        in.close();
    }

BufferedInputStream & BufferedOutputStream

注：BufferedInputStream ，BufferedOutputStream对字节流进行了包装，实现了缓冲区功能

    @Test
    public void test2() throws IOException {
        BufferedInputStream in = new BufferedInputStream(
                new FileInputStream("D:/QQWhatsnew.txt"));

        BufferedOutputStream out = new BufferedOutputStream(
                new FileOutputStream("out2.txt"));

        byte[] bytes = new byte[1024];
        int len;
        while ((len=in.read(bytes))!=-1){
            out.write(bytes,0,len);
        }

        out.close();
        in.close();
    }

字符流复制文件操作

注：D:/QQWhatsnew.txt的编码为UTF-8

FileReader & FileWriter

    @Test
    public void test3() throws IOException {
        Reader reader = new FileReader("D:/QQWhatsnew.txt");

        Writer writer = new FileWriter("out3.txt");

        char[] chars = new char[1024];
        int len;
        while ((len=reader.read(chars))!=-1){
            writer.write(chars,0,len);
        }

        writer.close();
        reader.close();
    }

BufferedReader & BufferedWriter
注：BufferedReader ，BufferedWriter对字符流进行了包装，实现了缓冲区功能

    @Test
    public void test4() throws IOException{
        BufferedReader reader = new BufferedReader(
                new FileReader("D:/QQWhatsnew.txt"));

        BufferedWriter writer = new BufferedWriter(
                new FileWriter("out4.txt"));

        char[] chars = new char[1024];
        int len;
        while ((len=reader.read(chars))!=-1){
            writer.write(chars,0,len);
        }

        writer.close();
        reader.close();
    }

将字节流转换为字符流

不指定编码

    @Test
    public void test5() throws IOException {
        Reader reader = new InputStreamReader(
                new FileInputStream("D:/QQWhatsnew.txt"));

        Writer writer = new OutputStreamWriter(
                new FileOutputStream("out5.txt"));

        char[] chars = new char[1024];
        int len;
        while ((len=reader.read(chars))!=-1){
            writer.write(chars,0,len);
        }

        writer.close();
        reader.close();
    }

指定编码

这样 out6.txt 就以GBK的编码方式查看

    @Test
    public void test6() throws IOException {
        Reader reader = new InputStreamReader(
                new FileInputStream("D:/QQWhatsnew.txt"),"Utf-8");
		
        Writer writer = new OutputStreamWriter(
                new FileOutputStream("out6.txt"),"GBK");

        char[] chars = new char[1024];
        int len;
        while ((len=reader.read(chars))!=-1){
            writer.write(chars,0,len);
        }

        writer.close();
        reader.close();
    }