Java输入输出处理技术1

1.保存用户输入到文件

从键盘读入一行字符，写到文件output.txt中去。

package io;

import java.io.*;

public class MyFileOutput {



    public static void main(String[] args) {

        FileInputStream fin;

        FileOutputStream fout;

        int ch;

        try {

            fin=new FileInputStream(FileDescriptor.in);

            fout=new FileOutputStream("output.txt");

            System.out.println("请输入一行字符:");

            while((ch=fin.read())!='\r')

                fout.write(ch);

            fin.close();

            fout.close();

            System.out.println("文件写入成功！");

        } catch (FileNotFoundException e) {

            System.out.println("不能创建文件!");

        }catch(IOException e){

            System.out.println("输出流有误！");

        }



    }



}

2.显示文件内容

显示文本文件的内容。

package io;

import java.io.*;

public class TypeFile {



    public static void main(String[] args) {

        FileInputStream fin;

        FileOutputStream fout;

        int ch;

        if(args.length<1){

            System.out.println("请指定文件名！");

            return;

        }

        try {

            fin=new FileInputStream(args[0]);

            fout=new FileOutputStream(FileDescriptor.out);

            while((ch=fin.read())!=-1)

                fout.write(ch);

            fin.close();

            fout.close();

        } catch (FileNotFoundException e) {

            System.out.println("文件没有找到！");

        } catch (IOException e) {

            System.out.println("输入流有误！");

        }

        

    }



}

3.文件的复制

文件复制程序。

package io;

import java.io.*;

public class CopyFile {



    public static void main(String[] args) {

        FileInputStream fin;

        FileOutputStream fout;

        int ch;

        if(args.length!=2){

            System.out.println("参数格式不对，应该为：java CopyFile 原文件名 目标文件名");

            return;

        }

        try {

            fin=new FileInputStream(args[0]);

            fout=new FileOutputStream(args[1]);

            while((ch=fin.read())!=-1)

                fout.write(ch);

            fin.close();

            fout.close();

            System.out.println("文件复制成功！");

        } catch (FileNotFoundException e) {

            System.out.println("文件没有找到！");

        } catch (IOException e) {

            System.out.println("读写文件有误！");

        }



    }



}

4.顺序输入流

顺序输入流示例。

package io;

import java.io.*;

import java.util.*;



public class FileList implements Enumeration{

    String MyFileList[];

    int current=0;

    public FileList(String filelist[]){

        MyFileList=filelist;

    }

    

    public FileList(){

        MyFileList=null;

    }

    

    public boolean hasMoreElements() {

        if(MyFileList==null)

            return false;

        if(current<MyFileList.length)

            return true;

        else

            return false;

    }

    

    public Object nextElement() {

        FileInputStream in=null;

        if(!hasMoreElements())

            return null;

        try {

            in = new FileInputStream(MyFileList[current]);

            current++;

        } catch (FileNotFoundException e) {

            System.out.println("Can't open file:"+MyFileList[current]);

        }

        return in;

    }



}

package io;

import java.io.*;

import java.util.*;

public class MySequenceIn {



    public static void main(String[] args) {

        FileList myList = new FileList(args);

        SequenceInputStream sin;

        FileOutputStream fout;

        int data;

        try {

            sin = new SequenceInputStream(myList);

            fout = new FileOutputStream(FileDescriptor.out);

            while((data=sin.read())!=-1)

                fout.write(data);

            sin.close();

            fout.close();

        } catch (FileNotFoundException e) {

            System.out.println("文件无法打开");

        } catch (IOException e) {

            System.out.println("读写文件有误");

        }



    }



}

5.管道输入输出流

管道输入输出流示例。

package io;

import java.io.*;

//本线程类用于发送数据

public class ThreadOut extends Thread {

    PipedInputStream pin;

    PipedOutputStream pout;

    byte data[]={1,2,3};

    public ThreadOut(PipedInputStream in, PipedOutputStream out){

        pin = in;

        pout = out;

    }

    

    public void run(){

        try {

            pout.write(data);

        } catch (IOException e) {

//            e.printStackTrace();

        }

    }

}

package io;

import java.io.*;

//本线程类用于接收数据

public class ThreadIn extends Thread {

    PipedInputStream pin;

    PipedOutputStream pout;

    int data;

    public ThreadIn(PipedInputStream in, PipedOutputStream out){

        pin = in;

        pout = out;

    }

    

    public void run(){

        try {

            while((data=pin.read())!=-1)

                System.out.println(data);

        } catch (IOException e) {

//            e.printStackTrace();

        }

    }

}

package io;

import java.io.*;

public class MyPipedIO {



    public static void main(String[] args) {

        PipedInputStream mypin=null;

        PipedOutputStream mypout=null;

        try {

            mypin = new PipedInputStream();

            mypout = new PipedOutputStream();

            mypin.connect(mypout);

            ThreadOut tout = new ThreadOut(mypin, mypout);

            ThreadIn tin = new ThreadIn(mypin, mypout);

            tout.start();

            tin.start();

        } catch (IOException e) {

            System.out.println("无法连接管道");

        }



    }



}

6.过滤输入输出流

数据输入输出流使用示例。

package io;

import java.io.*;

public class MyDataIO {



    public static void main(String[] args) {

        DataOutputStream dout;

        DataInputStream din;

        try {

            dout = new DataOutputStream(new FileOutputStream("testfile.dat"));

            dout.writeInt(100);

            dout.writeLong(123456789);

            dout.writeDouble(1.23456);

            dout.writeFloat(1.2f);

            dout.writeBoolean(true);

            

            din = new DataInputStream(new FileInputStream("testfile.dat"));

            System.out.println(din.readInt());

            System.out.println(din.readLong());

            System.out.println(din.readDouble());

            System.out.println(din.readFloat());

            System.out.println(din.readBoolean());

        } catch (FileNotFoundException e) {

            System.out.println("没有找到文件！");

        } catch (IOException e) {

            System.out.println("无法正常创建输入输出流数据!");

        }

        

    }



}