Java I/O简述

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

/**
 * 
 * @author fengkuirui
 * @date 2017-02-09
 * File类的主要方法测试;
 */
public class FileTest {
    public static void main(String[] args) throws IOException {
        File file = new File(".");//当前路径创建File对象;
        //输出文件名
        System.out.println(file.getName());//.
        //输出当前文件的绝对路径
        System.out.println(file.getAbsoluteFile());//D:\JAVA\SE\IO\.
        //获取相对路径得父路径
        System.out.println(file.getParent());//null
        //获取上一级目录
        System.out.println(file.getAbsoluteFile().getParent());//D:\JAVA\SE\IO
        //在当前路径下创建一个临时文件
        File temp = File.createTempFile("aaa",".txt",file);
        //指定当JVM退出时删除文件
        temp.deleteOnExit();
        //以当前时间作为新的文件名创建新文件
        File file2 = new File(System.currentTimeMillis()+"");
        //判断新建文件是否存在
        System.out.println(file2.exists());//false
        //用其创建文件
        file2.createNewFile();
        //创建目录
        file2.mkdir();
        //使用list()方法列出当前路径下的所有文件和路径
        String[] fileList = file.list();
        System.out.println("当前路路径下的所有文件和目录");
        for(String f : fileList){
            System.out.println(f);
        }
        //listRoot()静态的方法列出所有的磁盘根目录
        File[] roots = File.listRoots();
        System.out.println("==系统所有的根路径如下：");
        for(File root : roots){
            System.out.println(root);
        }
    
        System.out.println();
        
        
    }
}

import java.io.FileInputStream;

/**
 * Created by fengkuirui on 2016/10/27.
 * 演示应用FileInputStream读取文件类的基本使用，对文件进行进行读取
 *
 */
public class MyFileInputStream {
    /**
     *  显示读取文件中的内容，输出到控制台
     * @param path :文件的绝对路径加上文件名
     */
    public void ReadFile(String path){
        FileInputStream fis = null; //初始化文件流为空
        byte [] buffer = new byte[1024]; //读取缓存为1024个字节
        int n ;
        try{
            int i = 0;//记录读取的次数
            fis = new FileInputStream(path);
            while ((n = (fis.read(buffer))) != -1){//直至读取完毕后，结束此时 n = -1
                System.out.write(buffer,0,n);//将文件输出到控制台
                i++;//统计读取的次数
                System.out.println("=--------=");
                System.out.println(n);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally{
            try{
                if(fis != null){
                    fis.close();//关闭
                }
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }
    public static void main(String[] args) {
        MyFileInputStream mfis = new MyFileInputStream();
        mfis.ReadFile("E://read.txt");//送的为绝对路径
    }
}


import java.io.FileOutputStream;
import java.io.PrintStream;

/**
 * Created by fengkuirui on 2016/10/27.
 * 用FileOutputStream写入文件
 */
public class MyFileOutputStream {
    /**
     * 将内容保存到文件
     * @param path :要保存的文件的绝对路径，包含文件名和后缀;
     *
     */
    public void WriteFile(String path){
        FileOutputStream fos = null;
        //声明一个PrintStream流
        PrintStream prints;
        try{
            fos = new FileOutputStream(path,true);//默认为覆盖内容的形式，如果设为true，为追加内容的方式
            prints = new PrintStream(fos);
            prints.println("世界这么大，我想去看看");
            prints.println("可是我没有时间啊");
            prints.close();
            System.out.println("写入文件完毕！");
        }catch (Exception e){
            e.printStackTrace();
        }finally{
            try{
                if(fos != null){
                    fos.flush();
                    fos.close();
                }
            }catch (Exception e){
                e.printStackTrace();
            }

        }

    }
    public static void main(String[] args) {
        MyFileOutputStream mfos = new MyFileOutputStream();
        mfos.WriteFile("E://write.txt");
    }
}

import java.io.BufferedReader;
import java.io.FileReader;

/**
 * Created by fengkuirui on 2016/10/27.
 * 利用字符流读取文件
 */
public class MyReader {
    public void readFile(String path){
        FileReader fr = null;
        String str ;
        try{
            fr = new FileReader(path);
            BufferedReader buf = new BufferedReader(fr);//包装流
            str = new String();
            int i =0 ;
            while((str = buf.readLine()) != null){//每次只读一行
                System.out.println(str);
                System.out.println(i);
                i++;
                System.out.println("++++++++++++++");
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally{
            try{

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

    }
    public static void main(String[] args) {
        MyReader reader = new MyReader();
        reader.readFile("E://read.txt");
    }
}


import java.io.FileWriter;
import java.io.PrintWriter;

/**
 * Created by fengkuirui on 2016/10/27.
 * 字符流写入文件
 */
public class MyWriter {
    /**
     *
     * @param path ：要保存的文件的路径和名称加后缀
     */
    public void writeFile(String path){
        FileWriter fw = null;
        PrintWriter prints = null;
        try{
            fw = new FileWriter(path);
            prints = new PrintWriter(fw);//包装流;
            prints.println("我要学习Java，决不放弃！");
            prints.println("Never give up");
        }catch (Exception e){
            e.printStackTrace();
        }finally{

            if(prints != null){
                prints.flush();
                prints.close();
            }
        }
    }

    public static void main(String[] args) {
        MyWriter myw = new MyWriter();
        myw.writeFile("E://write.txt");
        MyReader myr = new MyReader();
        myr.readFile("E://write.txt");
    }
}

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;

/**
 * Created by fengkuirui on 2016/10/27.
 * 包装流到缓冲流
 * 提高读取速度
 */
public class MyBufferStream {
    /**
     *
     * @param path :读取文件的路径
     */
    public void read(String path){
        File file = null;
        FileInputStream fis = null;
        BufferedInputStream bis = null;
        try{
            file = new File(path);//声明文件
            fis = new FileInputStream(file);//文件输入流
            bis = new BufferedInputStream(fis,1024);//设置缓存大小为1024字节
            byte[] data = new byte[(int)file.length()];
            while(bis.read(data) != -1){
                String str=new String(data);
                System.out.print(str);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally{
            try{
                if(bis != null){
                    bis.close();
                }

                if(fis != null){
                    fis.close();
                }

            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }
    public static void main(String[] args) {
        MyBufferStream mbs = new MyBufferStream();
        mbs.read("E://read.txt");
    }
}

import java.io.File;
import java.io.RandomAccessFile;

/**
 * Created by fengkuirui on 2016/10/27.
 * 利用RandomAccessFile 进行文件的合并
 */
public class MyRandomAccessFile {

    public void insert(String path1, String path2){
        File file1 = null;
        File file2 = null;
        RandomAccessFile raf1 = null;
        RandomAccessFile raf2 = null;
        try{
            file1 = new File(path1);
            file2 = new File(path2);
            raf1 = new RandomAccessFile(file1,"rw");
            raf2 = new RandomAccessFile(file2,"rw");
            byte[] buffer = new byte[1024];
            raf1.seek(raf1.length());//定位到最后，在最后添加；
            int n ;
            while((n=(raf2.read(buffer))) != -1){
                raf1.write(buffer,0,n);
            }
            raf1.close();
            raf2.close();
        } catch(Exception e){
            e.printStackTrace();
        }finally{
            try{

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

    }
    public static void main(String[] args) {
        MyRandomAccessFile mraf = new MyRandomAccessFile();
        mraf.insert("E://read.txt","E://write.txt");
        MyFileInputStream mfis = new MyFileInputStream();
        mfis.ReadFile("E://read.txt");
    }
}

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

/**
 * Created by fengkuirui on 2016/10/27.
 * ByteArrayInputStream and ByteArrayOutputStream ,
 * 直接将多个数据转化成字节数组
 */
public class MyByteArrayStream {
   public void get(){
       int a = 1;
       int b = 12;
       int c = 123;
       ByteArrayOutputStream baos = new ByteArrayOutputStream();
       baos.write(a);
       baos.write(b);
       baos.write(c);
       byte[] buffer = baos.toByteArray();
       System.out.println("将字节流转换为字节数组为：");
       for(byte i : buffer){
           System.out.println(i);
       }
       //将字节数组转换为字节流
       ByteArrayInputStream bais = new ByteArrayInputStream(buffer);
        int bb;
       while((bb = bais.read()) != -1){
           System.out.println(bb);
       }
   }


    public static void main(String[] args) {
        MyByteArrayStream mbaos = new MyByteArrayStream();
        mbaos.get();
    }
}