Java IO强记

应付面试吧：

package colin;

import java.io.File;
import java.io.IOException;

public class IOTest {
    public static void main(String[] args) {
        //创建一个文件路径
        File file = new File("/log/testData.txt");
        if (file.exists()) {
//得到文件路径
            System.out.println(file.getAbsolutePath());
//得到文件大小
            System.out.println("文件大小：" + file.length());
        } else {
            try {
                file.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
//创建文件和创建文件夹
        File file1 = new File("/log/iotest.txt");
        if (!file1.exists()) {
            try {
                file1.createNewFile();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } else {
            System.out.println("文件已存在");
        }
//创建文件夹
        File file2 = new File("/log/testIO");
        if (file2.isDirectory()) {
            System.out.println("文件夹存在");
        } else {
            file2.mkdir();
        }

//列出一个文件夹下的所有文件
        File f = new File("/log/testIO");
        if (f.isDirectory()) {
            File lists[] = f.listFiles();
            for (int i = 0; i < lists.length; i++) {
                System.out.println(lists[i].getName());
            }
        }
    }
}

对文本类的处理：

package colin;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;

public class WriteText {
    public static void main(String[] args) {
        writeText();
    }

    private static void writeText() {

        try {
            FileReader fr=new FileReader("/log/1.txt");
            FileWriter fw = new FileWriter("/log/2.txt");
            BufferedReader br=new BufferedReader(fr);
            BufferedWriter bw=new BufferedWriter(fw);
            String len;
            while ((len=br.readLine())!=null){
                bw.write(len);
            }
            bw.close();
            br.close();

//            fw.write("我很好，你呢？");
//            fw.flush();
//            fw.write("如果有一天你要走，请告诉我");

            fw.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

对于图片的处理：

package colin;

import java.io.FileInputStream;
import java.io.FileOutputStream;

public class CopyPic {
    public static void main(String[] args) {
        copyPic();
    }

    public static void copyPic(){
        try {
            FileInputStream fis=new FileInputStream("/log/p1/p1.png");
            FileOutputStream fos=new FileOutputStream("/log/p2/p2.png");
            byte[] bytes=new byte[1024];
            int len=0;
            while((len=fis.read(bytes))!=-1){
                fos.write(bytes,0,len);
            }


        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}