java 文件操作

一、获取文件列表

　　方法一：DirFilter类实现了FilenameFilter接口，需要重写FilenamFilter中的accept方法。

/**
 * java文件操作  获取文件列表
 * 2016/6/15
 */
package fileStream;

import java.io.File;
import java.io.FilenameFilter;
import java.util.regex.*;
import java.util.*;

public class DirList {
    public static void main(String[] args){
        File path = new File("G:");
        String[] list;
        if(args.length == 0){
            list = path.list();
        }else{
            list = path.list(new DirFilter(args[0]));
        }
        Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
        for(String dirItem:list){
            System.out.println(dirItem);
        }
    }
}

class DirFilter implements FilenameFilter {
    private Pattern pattern;
    public DirFilter(String regex){
        pattern = Pattern.compile(regex);
    }
    @Override
    public boolean accept(File dir, String name) {
        return pattern.matcher(name).matches();
    }
}

　　方法二：使用匿名内部类

/**
 * 获取文件列表方法2  匿名内部类
 * 2016/6/15
 */
package fileStream;

import java.io.*;
import java.util.*;
import java.util.regex.*;


public class DirList2 {
    public static FilenameFilter filter(final String regex){
        return new FilenameFilter(){
            private Pattern pattern = Pattern.compile(regex);
            @Override
            public boolean accept(File dir, String name){
                return pattern.matcher(name).matches();
            }
        };
    }
    public static void main(String[] args){
        File path = new File("G:");
        String[] list;
        if(args.length == 0){
            list = path.list();
        }else{
            list = path.list(new DirFilter(args[0]));
        }
        Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
        for(String dirItem:list){
            System.out.println(dirItem);
        }
    }

}

　　方法二改进：

/**
 * Thinking in Java
 * 获取文件列表  方法二改进
 * 2016/6/15
 */
package fileStream;

import java.util.*;
import java.util.regex.*;
import java.io.*;

public class DirList3 {
    public static void main(final String[] args){
        File path = new File("G:");
        String[] list;
        if(args.length == 0){
            list = path.list();
        }else{
            list = path.list(new FilenameFilter() {
                private Pattern pattern = Pattern.compile(args[0]);
                public boolean accept(File dir, String name) {
                    return pattern.matcher(name).matches();
                }
            });
        }
            Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
            for(String dirItem : list){
                System.out.println(dirItem);
            }
    }
}

二、文本文件的读写

/**
 * 文本文件的读写
 * 2016/6/15
 */
package fileStream;

import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;


public class FileStream {
    public static void main(String[] args) throws IOException{
        //写入文件
        FileOutputStream outFile = new FileOutputStream("E:/1.txt",true);
        StringBuffer outText = new StringBuffer();
        String str = null;
        Scanner input = new Scanner(System.in);
        byte[] writeByte = null;
        while(true){
            str = input.nextLine();
            outText.append(str);
            if(str.equals("quit")) break;
        }
        
        writeByte = (outText+"").getBytes();
        outFile.write(writeByte);
        outFile.close();
        
        //读取文件
        BufferedReader  reader = new BufferedReader(new FileReader("E:/1.txt"));
        String text = null;    
        while((text = reader.readLine()) != null){
            System.out.println(text);
        }
        reader.close();
    }
}

三、二进制文件的读取

//此处只提供方法，主函数请自行书写
public static byte[] read(File bfile) throws IOException {
        BufferedInputStream bf = new BufferedInputStream(new FileInputStream(bfile));
        try {
            byte[] data = new byte[bf.available()];
            bf.read(data);
            return data;
        } catch (Exception e) {
            // TODO: handle exception
        }finally{
            bf.close();
        }
        return null;
    }

四、进程控制

　　传入操作系统的命令，后台运行后获取输出，并打印出来。

/**
 * Thinking in Java
 * 进程控制  运行操作系统命令，发送输出到控制台
 * 2016/6/16
 */
package fileStream;
import java.io.*;

public class OSExecute {
    public static void command(String command) {
        boolean err = false;
        try {
            //创建一个新的Process实例
            Process process = new ProcessBuilder(command.split(" ")).start();
            BufferedReader results = new BufferedReader(new InputStreamReader(process.getInputStream()));
            String s;
            while((s = results.readLine()) != null){
                System.out.println(s);
            }
            //获取错误信息
            BufferedReader errors = new BufferedReader(
                    new InputStreamReader(process.getErrorStream()));
            while ((s = errors.readLine()) != null) {
                System.err.println(s);
                err = true;
            }
        }catch(Exception e) {
            if(!command.startsWith("CMD /C")){
                command("CMD /C" + command);
            }else{
                throw new RuntimeException(e);
            }
            if(err){
//                throw new OSExecuteException("Errors executing " + command);
            }
        }
    }
    public static void main(String[] args){
        String path="F:\java\work_1\Stream\bin\fileStream/";  
        String commandw="javap "+path+"OSExecute.class";  
        OSExecute.command(commandw);    //传入CMD命令
    }
}

五、新I/O

JDK1.4中的java.nio.*包引入了行动JavaI/O类库，可以提高读取速度。

/**
 * Thinking in Java P552
 * java 新I/O
 * 2016/6/16
 */
package fileStream;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class GetChannel {
    private static final int BSIZE = 1024;
    public static void main(String[] args){
        try {
            //写入文件
            FileChannel  fc = new FileOutputStream("1.txt").getChannel();
            fc.write(ByteBuffer.wrap("hello world".getBytes()));
            fc.close();
            //在文件尾添加内容
            fc = new RandomAccessFile("1.txt", "rw").getChannel();
            fc.position(fc.size());        //移动到文件末尾
            fc.write(ByteBuffer.wrap("More Hello World".getBytes()));
            fc.close();
            //读取文件
            fc = new FileInputStream("1.txt").getChannel();
            ByteBuffer buff = ByteBuffer.allocate(BSIZE);
            fc.read(buff);
            buff.flip();
            while(buff.hasRemaining()){
                System.out.print((char)buff.get());
            }
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    

}

 六、文件复制

/**
 * Thinking in Java
 * 文件复制
 * 2016/6/16
 */
package fileStream;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class ChannelCopy {
    private static final int BSIZE = 1024;
    public static void main(String[] args) throws Exception {
        File sourceFile = new File("1.txt");    //源文件
        File DestFile = new File("1_copy.txt");    //要复制的目标文件

        FileChannel in = new FileInputStream(sourceFile).getChannel();
        FileChannel out = new FileOutputStream(DestFile).getChannel();
        ByteBuffer buffer = ByteBuffer.allocate(BSIZE);
        while (in.read(buffer) != -1) {
            buffer.flip();
            out.write(buffer);
            buffer.clear();
        }
        in.close();
        out.close();
    }

}

七、文件内容替换

/**
 * 替换某文件夹下所有以.txt 结尾的文件中的"java"字符串，替换为"****"
 */
package com;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

public class ReadAllFile {

    // 读取一个文件夹下所有文件及子文件夹下的所有文件
    public static void readAllFile(String filePath) {
        File f = new File(filePath);
        File[] files = f.listFiles(); // 得到f文件夹下面的所有文件。
        List<File> list = new ArrayList<File>();
        for (File file : files) {
            if (file.isDirectory()) {
                // 如何当前路劲是文件夹，则循环读取这个文件夹下的所有文件
                readAllFile(file.getAbsolutePath());
            } else {
                list.add(file);
            }
        }
        for (File file : files) {
            String fileName = file.getName();
            if (fileName.endsWith("txt")) {
                // 替换所有的java字符串
                replace(file);
            }
        }
    }

    //替换
    private static void replace(File file) {
        InputStreamReader isr;
        OutputStreamWriter osw;
        try {
            isr = new InputStreamReader(new FileInputStream(file), "UTF-8");
            BufferedReader br = new BufferedReader(isr);
            String str = "";
            StringBuffer index = new StringBuffer();
            while ((str = br.readLine()) != null) {
                System.out.println(str);
                index.append(str.replaceAll("java", "****") + '
');
            }
            osw = new OutputStreamWriter(new FileOutputStream(file), "UTF-8");
            osw.write(index.toString());
            osw.flush();
            br.close();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static void main(String[] args) {
        String filePath = "F:\Test";
        readAllFile(filePath);
    }
}