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!");
        }
        
    }

}