文件IO常用操作

package com.gu.file;

import java.io.File;
//相对路径与绝对路径构建file对象
public class Demo1 {
public static void main(String[] args) {
    
    //String path="E:"+File.pathSeparator+"";
    String parentPath="E";
    String name="2.txt";
    //相对
    File f=new File(parentPath, name);
    System.out.println(f.getName());
    //在当前路径下构建文件
    f=new File("test.txt");
    System.out.println(f.getName());
    System.out.println(f.getAbsolutePath());
    //绝对路径
    f=new File("E:/test2");
    System.out.println(f.getAbsolutePath());
    
    
}
}



package com.gu.file;

import java.io.File;
import java.io.FilenameFilter;
import java.util.Arrays;


/**
 * 输出目录下文件
 * @author 谷
 *
 */
public class Demo2 {
    public static void main(String[] args) {
        String path="E:/test";
        File parent =new File(path);
        //printName(parent);
        //printFiles(parent);
        
        
        
        File []roots=File.listRoots();
        System.out.println(Arrays.toString(roots));
    }
    
    //递归显示所有子文件和文件夹
public static void printFiles(File src){
    if(src==null||!src.exists()){
        return  ;
    }
    
    System.out.println(src.getAbsolutePath());
        
    if(src.isDirectory()){
        for(File f:src.listFiles()){
            printFiles(f);
            
            
        }
    }
    }
    //递归显示所有子文件
    public static void printName(File src){
        
        
        getdric(src);
        File []files=src.listFiles(new FilenameFilter() {
            
            @Override
            public boolean accept(File dir, String name) {
                
                return new File(dir, name).isDirectory();
            }
        });
        for(File ff:files){
            //System.out.println(ff.getAbsolutePath());
            printName(ff);
        }
    }
    //获取当前目录下的子文件夹
    public static void getdric(File src){
        if(src==null||!src.exists()){
            return  ;
        }
        
        if(src.isDirectory()){
            for(File f:src.listFiles(new FilenameFilter() {
                
                @Override
                public boolean accept(File dir, String name) {
                    
                    return new File(dir, name).isFile();
                }
            })){
                System.out.println(f.getAbsolutePath());
                src=f;
                
            }
        }

package com.gu.stream;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * 字节缓冲流无新增方法,但提高性能
 * 字符缓冲流有reader.readLine(),write.newLine（）；
 * 例如：String line=null;
 * while(null!=(line=bufferedreader.readline))
 * 替换：char[]in=new char[1024];
 * int len=0;
 * while(-1!=(len=reader.read(in))) 
 * @author 谷
 *
 */

public class filecopyUtil {
    public static void main(String[] args) {
        File src=new File ("E:/test/dd/Demo1.txt");
        File dest=new File ("E:/test/");
        try {
            copyFile(src, dest);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static void copyFile(String srcPath,String destpath) throws IOException {
        
        copyFile(new File (srcPath),new File(destpath));
    }
    
    
    public static void copyFile(File src,File dest) throws IOException ,FileNotFoundException{
        
        if(!src.isFile()){
            System.out.print("不是文件");
            throw new IOException("只能拷贝文件");
        }
        if(src==null||!src.exists()){
            return  ;
        }
        BufferedInputStream in=new BufferedInputStream(new FileInputStream(src));
        //OutputStream out=new FileOutputStream(dest);
        BufferedOutputStream out=new BufferedOutputStream(new FileOutputStream(dest));
        //BufferedOutputStream ，BufferedInputStream 无新增方法
        byte[]car=new byte[10];
        int len;
        while(-1!=(len=in.read(car))){
            out.write(car, 0, len);
            
        }
        out.flush();
        
        in.close();
        out.close();
        
    }
}

    }
    
    

}