iodemo.java

java 使用FileStream 复制文件

package day7;

import java.io.*;

public class IODemo {
    public static void main(String[] args) {
        //writeFile();
        //readFile();
        copyFile();
    }

    public static void readFile() {
        File f = new File("abc.txt");
        if (!f.exists()) {
            System.out.println("file not found!");
            return;
        }
        FileReader fr = null;
        BufferedReader br = null;
        try {
            fr = new FileReader(f);
            br = new BufferedReader(fr);
            String str = "";
            while ((str = br.readLine()) != null) {
                System.out.println(str);
            }
            br.close();
            fr.close();
        } catch (Exception ex) {
            System.out.println("ex: " + ex.getMessage());
        }
    }

    public static void writeFile() {
        File f = new File("abc.txt");
        System.out.println(
                "path:" + f.getAbsolutePath());
        FileWriter fw = null;
        BufferedWriter bw = null;
        try {
            fw = new FileWriter(f);
            bw = new BufferedWriter(fw);
            bw.write("Welcome");
            bw.newLine();
            bw.write("Hello World");
            bw.flush();
            bw.close();
            fw.close();
        } catch (Exception ex) {
            System.out.println("ex :" + ex.getMessage());
        }
    }

    public static void copyFile() {
        String fSrc = "";
        String fDest = "";
        FileInputStream fis = null;
        FileOutputStream fos = null;
        InputStreamReader bis =
                new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(bis);
        try {
            System.out.println("pls input source file:");
            fSrc = br.readLine();
            System.out.println("pls input dest file:");
            fDest = br.readLine();
            File f1 = new File(fSrc);
            if (!f1.exists()) {
                System.out.println("file " + fSrc +
                                   " not found!");
                return;
            }
            File f2 = new File(fDest);
            if (f2.exists()) {
                System.out.println(
                        "overwrite?(y/n)");
                String echo = br.readLine();
                if (echo.equalsIgnoreCase("n")) {
                    return;
                }
            }
            fis=new FileInputStream(f1);
            fos=new FileOutputStream(f2);
            int b;
            while((b=fis.read())!=-1)
            {
                fos.write(b);
            }
            fos.close();
            fis.close();
            System.out.println("copy file success!");

        } catch (Exception ex) {

        } finally {

        }

    }
}