// 一次讀多個字節(jié)
            byte[] tempbytes = new byte[100];
            int byteread = 0;
            in = new FileInputStream(fileName);//①
            ReadFromFile.showAvailableBytes(in);
            // 讀入多個字節(jié)到字節(jié)數(shù)組中，byteread為一次讀入的字節(jié)數(shù)
            while ((byteread = in.read(tempbytes)) != -1) { //②
                System.out.write(tempbytes, 0, byteread);
            }

  RandomAccessFile raf=new RandomAccessFile(new File("D:\\3\\test.txt"), "r");   
            //獲取RandomAccessFile對象文件指針的位置，初始位置是0  
            System.out.println("RandomAccessFile文件指針的初始位置:"+raf.getFilePointer());  
            raf.seek(pointe);//移動文件指針位置  
            byte[]  buff=new byte[1024];  
            //用于保存實際讀取的字節(jié)數(shù)  
            int hasRead=0;  
            //循環(huán)讀取  
            while((hasRead=raf.read(buff))>0){  
                //打印讀取的內(nèi)容,并將字節(jié)轉(zhuǎn)為字符串輸入  
                System.out.println(new String(buff,0,hasRead));       
            }  

public static void insert(String fileName, long pos, String insertContent) throws IOException{
        File file = File.createTempFile("tmp", null);
        file.deleteOnExit();
        RandomAccessFile raf = new RandomAccessFile(fileName, "rw");
        FileInputStream fileInputStream = new FileInputStream(file);
        FileOutputStream fileOutputStream = new FileOutputStream(file);
        raf.seek(pos);
        byte[] buff = new byte[64];
        int hasRead = 0;
        while((hasRead = raf.read(buff)) > 0){
            fileOutputStream.write(buff);
        }
        raf.seek(pos);
        raf.write(insertContent.getBytes());
        //追加文件插入點之后的內(nèi)容
        while((hasRead = fileInputStream.read(buff)) > 0){
            raf.write(buff, 0, hasRead);
        }
        raf.close();
        fileInputStream.close();
        fileOutputStream.close();
    }