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，。