IO开篇！

五个类

• File 文件类
• InputStream 字节输入流
• OutputStream 字节输出流
• Reader 字符输入流
• Writer 字符输出流

  三个接口

• Closeable 关闭流接口
• Flushable 刷新流接口
• Serializable 序列化接口

测试路径

package com.yishan.io;

import java.io.File;

/**
* 测试路径
* @author yishan
*/
public class TestIoDemo01 {
    public static void main(String[] args) {
        String path = "F:\\My direction\\java SE\\IO\\src\\111.png";
        System.out.println(File.separatorChar);
        //建议
        path = "F:/My direction/java SE/IO/src/111.png";
        System.out.println(path);
        //常量拼接
        path = "F:"+File.separatorChar+"My direction"+File.separatorChar+"java SE"+File.separatorChar+"IO"+File.separatorChar+"src"+File.separatorChar+"111. png ";
        System.out.println(path);
    }
}

测试构造器

package com.yishan.io;

import sun.net.www.content.image.png;

import java.io.File;

/**
* 测试构造器
* @author yishan
*/
public class FileDemo01 {
    public static void main(String[] args) {
        /**
        * 构建File对象
        */
    String path = "F:/My direction/java SE/IO/src/111.png";

    //1.构建File对象
        File src = new File(path);
        System.out.println(src.length());

        //2.构建File对象
        src = new File("F:/My direction/java SE/IO/src", "111.png ");
        System.out.println(src.length());
        src = new File("F:/My direction","java SE/IO/src/111.png ");
        System.out.println(src.length());

        //3.构建File对象
        src = new File(new File("F:/My direction/java SE/IO/src"),"111.png");
        System.out.println(src.length());
    }
}

测试相对路径和绝对路径

package com.yishan.io;

import java.io.File;

/**
* 测试相对路径和绝对路径
* @author yishan
*/
public class FileDemo02 {
    public static void main(String[] args) {
        /**
        * 构建File对象
        * 相对路径和绝对路径
        * 1.存在盘符：绝对路径
        * 2.不存在盘符：相对路径  当前目录：user.dir
        */
    String path = "F:/My direction/java SE/IO/src/111.png";
        //绝对路径
        File src = new File(path);
        System.out.println(src.getAbsolutePath());

        //相对路径
        System.out.println(System.getProperty("user.dir"));
        src = new File("111.png");
        System.out.println(src.getAbsolutePath());

        //构建一个不存在的文件
        src = new File("aaa.png");
        System.out.println(src.getAbsolutePath());
    }
}

赏

谢谢你请我吃糖果