Rhythmk 一步一步学 JAVA (19) JAVA IO 文件常用操作

package com.rhythmk.filedemo;



import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.Reader;

import java.text.DateFormat;

import java.text.FieldPosition;

import java.text.ParsePosition;

import java.text.SimpleDateFormat;

import java.util.Properties;

import java.util.UUID;



import org.junit.Test;



public class file_demo1 {



    public String getPath() {

        return System.getProperty("user.dir");

    }



    @Test

    public void 获取系统路径() {

        String path = System.getProperty("user.dir");

        System.out.println(path);

    }



    @Test

    public void 写入文件() throws IOException {

        String filePath = getPath() + "\\a.txt";

        File file = new File(filePath);



        if (file.canWrite()) {

            System.out.println("可写");

        }

        FileWriter writer = new FileWriter(file, true);



        // 写入时间

        SimpleDateFormat time = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        writer.write("-------" + time.format(new java.util.Date()) + "\r\n");

        // 写入随机GUID

        writer.write(UUID.randomUUID().toString() + "\r\n");

        writer.flush();

        writer.close();



        System.out.println("写入文件成功路径：" + filePath);



    }



    @Test

    public void 读取文件() throws IOException {



        String filePath = getPath() + "\\a.txt";

        BufferedReader reader = new BufferedReader(new InputStreamReader(

                new FileInputStream(filePath), "UTF-8"));

        String txt = null;

        while ((txt = reader.readLine()) != null) {

            System.out.println(txt);



        }



    }



    @Test

    public void 遍历文件夹() throws IOException {

        String filePath = getPath() + "\\src";

        ReadFile(filePath);



    }



    private void ReadFile(String path) throws IOException {

        File file = new File(path);



        if (file.isDirectory()) {

            System.out.println("当前目录地址为:" + path + "\r\n");

            File[] filelist = file.listFiles();

            for (File f : filelist) {

                ReadFile(f.getAbsolutePath());



            }

        } else {

            System.out.println("------当前文件地址为:" + path + "\r\n");

            BufferedReader reader = new BufferedReader(new InputStreamReader(

                    new FileInputStream(path), "UTF-8"));

            String txt = null;

            while ((txt = reader.readLine()) != null) {

                System.out.println(txt);



            }

        }

    }



    @Test

    public void 删除文件() {

        String filePath = getPath() + "\\12.txt";

        File file = new File(filePath);

        file.deleteOnExit();

    }



    

    @Test

    public void 获取文件信息() {

        String filePath = getPath() + "\\a.txt";

        File file = new File(filePath);

        System.out.println("是否可读(canRead):" + file.canRead());

        System.out.println("当前文件路径(getAbsolutePath):" + file.getAbsolutePath());

        System.out.println("文件名称:" + file.getName());

        System.out.println("文件大小:" + file.length());

        System.out.println("文件是否存在:" + file.exists());

        String fileNAME = file.getName();

        System.out.println("后缀名:"

                + fileNAME.substring(fileNAME.lastIndexOf(".") + 1));

    }



    @Test

    public void 重命名() {

        String filePath = getPath() + "\\a.txt";

        File file = new File(filePath);

        File file2 = new File(getPath() + "\\aaa.txt");

        file.renameTo(file2);



        System.out.println("文件是否存在:" + file2.exists());



    }



    @Test

    public void 读取属性文件() {

        String filePath = getPath() + "\\src\\app.properties";

        Properties pro = new Properties();

        try {

            InputStream input = new FileInputStream(new File(filePath));

            pro.load(input);

            input.close();

        } catch (Exception e) {

            // TODO: handle exception

        }

        System.out.println(pro.getProperty("rhythmk"));

    }



}

 

如果迷茫，脚下的路不知道怎么走是好的时候，不要浪费时间在路口徘徊，凭感觉选择一条路走下去，。