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。

 1 /**
 2  * java文件操作  获取文件列表
 3  * 2016/6/15
 4  */
 5 package fileStream;
 6
 7 import java.io.File;
 8 import java.io.FilenameFilter;
 9 import java.util.regex.*;
10 import java.util.*;
11
12 public class DirList {
13     public static void main(String[] args){
14         File path = new File("G:");
15         String[] list;
16         if(args.length == 0){
17             list = path.list();
18         }else{
19             list = path.list(new DirFilter(args[0]));
20         }
21         Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
22         for(String dirItem:list){
23             System.out.println(dirItem);
24         }
25     }
26 }
27
28 class DirFilter implements FilenameFilter {
29     private Pattern pattern;
30     public DirFilter(String regex){
31         pattern = Pattern.compile(regex);
32     }
33     @Override
34     public boolean accept(File dir, String name) {
35         return pattern.matcher(name).matches();
36     }
37 }

　　方法二：使用匿名内部类

 1 /**
 2  * 获取文件列表方法2  匿名内部类
 3  * 2016/6/15
 4  */
 5 package fileStream;
 6
 7 import java.io.*;
 8 import java.util.*;
 9 import java.util.regex.*;
10
11
12 public class DirList2 {
13     public static FilenameFilter filter(final String regex){
14         return new FilenameFilter(){
15             private Pattern pattern = Pattern.compile(regex);
16             @Override
17             public boolean accept(File dir, String name){
18                 return pattern.matcher(name).matches();
19             }
20         };
21     }
22     public static void main(String[] args){
23         File path = new File("G:");
24         String[] list;
25         if(args.length == 0){
26             list = path.list();
27         }else{
28             list = path.list(new DirFilter(args[0]));
29         }
30         Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
31         for(String dirItem:list){
32             System.out.println(dirItem);
33         }
34     }
35
36 }

　　方法二改进：

 1 /**
 2  * Thinking in Java
 3  * 获取文件列表  方法二改进
 4  * 2016/6/15
 5  */
 6 package fileStream;
 7
 8 import java.util.*;
 9 import java.util.regex.*;
10 import java.io.*;
11
12 public class DirList3 {
13     public static void main(final String[] args){
14         File path = new File("G:");
15         String[] list;
16         if(args.length == 0){
17             list = path.list();
18         }else{
19             list = path.list(new FilenameFilter() {
20                 private Pattern pattern = Pattern.compile(args[0]);
21                 public boolean accept(File dir, String name) {
22                     return pattern.matcher(name).matches();
23                 }
24             });
25         }
26             Arrays.sort(list, String.CASE_INSENSITIVE_ORDER);
27             for(String dirItem : list){
28                 System.out.println(dirItem);
29             }
30     }
31 }

二、文本文件的读写

 1 /**
 2  * 文本文件的读写
 3  * 2016/6/15
 4  */
 5 package fileStream;
 6
 7 import java.io.BufferedReader;
 8 import java.io.FileOutputStream;
 9 import java.io.FileReader;
10 import java.io.IOException;
11 import java.util.Scanner;
12
13
14 public class FileStream {
15     public static void main(String[] args) throws IOException{
16         //写入文件
17         FileOutputStream outFile = new FileOutputStream("E:/1.txt",true);
18         StringBuffer outText = new StringBuffer();
19         String str = null;
20         Scanner input = new Scanner(System.in);
21         byte[] writeByte = null;
22         while(true){
23             str = input.nextLine();
24             outText.append(str);
25             if(str.equals("quit")) break;
26         }
27
28         writeByte = (outText+"").getBytes();
29         outFile.write(writeByte);
30         outFile.close();
31
32         //读取文件
33         BufferedReader  reader = new BufferedReader(new FileReader("E:/1.txt"));
34         String text = null;
35         while((text = reader.readLine()) != null){
36             System.out.println(text);
37         }
38         reader.close();
39     }
40 }