在java中读取文件中的内容

 package shi;

 import java.io.*;

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

         try {
             fis=new FileInputStream(f);
             byte[]arr=new byte[(int)f.length()];
             fis.read(arr);
             String str= new String (arr);
             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{
                     fis.close();
                 }
                 catch(IOException e){
                     e.printStackTrace();
                 }
             }
         }

     }

 }

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();
                }
            }
        }

    }
}