在java中读取文件中的内容

 1 package shi;
 2
 3 import java.io.*;
 4
 5 public class wenjianIO {
 6     public static void main(String agrs[]){
 7         FileInputStream fis=null;
 8         File f=new File("F:/test/javakc.txt");
 9
10         try {
11             fis=new FileInputStream(f);
12             byte[]arr=new byte[(int)f.length()];
13             fis.read(arr);
14             String str= new String (arr);
15             System.out.println(str);
16
17         } catch (FileNotFoundException e) {
18             // TODO Auto-generated catch block
19             e.printStackTrace();
20         } catch (IOException e) {
21             // TODO Auto-generated catch block
22             e.printStackTrace();
23         }
24         finally{
25             if(fis!=null){
26                 try{
27                     fis.close();
28                 }
29                 catch(IOException e){
30                     e.printStackTrace();
31                 }
32             }
33         }
34
35     }
36
37 }

java向文件中读写内容

package shi;

import java.io.*;

public class wenjianIO {
    public static void main(String agrs[]){
        FileInputStream fis=null;
        FileOutputStream fos=null;
        File f=new File("F:/test/javakc.txt");

        try {
//            向文件中写内容
            fos=new FileOutputStream(f);
            String s="你的小EZ,有走歪了";
            byte[]b=s.getBytes();
            fos.write(b);

//            向文件中读取内容
            fis=new FileInputStream(f);
            byte[]b2=new byte[(int) f.length()];
            fis.read(b2);
            String str=new String (b2);
            System.out.println(str);

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally{
            if(fis!=null){
                try{
                    fos.close();
                    fis.close();

                }
                catch(IOException e){
                    e.printStackTrace();
                }
            }
        }

    }
}