RandomAccessFile類的使用(隨機讀取java中的檔案)

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package coreJava;import java.io.File;import java.io.IOException;import java.io.RandomAccessFile;import java.util.Arrays;public class RandomAccessFileWriteandRead {    public static void main(String[] args)throws IOException {        // TODO Auto-generated method stub        File demo = new File("demo");        if(!demo.exists())            demo.mkdir();        File file = new File(demo,"raf.dat");        if(!file.exists())            file.createNewFile();        RandomAccessFile raf = new RandomAccessFile(file,"rw");        //擷取指標的位置：        System.out.println(raf.getFilePointer());                raf.write(‘A‘);//唯寫了一個位元組        System.out.println(raf.getFilePointer());        raf.write(‘B‘);                int i = 0x7fffffff;                //用write方法一次只能寫一個位元組。如果要把i寫進去的就得寫四次        raf.write(i>>>24);//高8位        raf.write(i>>>16);        raf.write(i>>>8);        raf.write(i);        System.out.println(raf.getFilePointer());        //可以直接寫一個int        raf.writeInt(i);        String s = "中";        byte[] gbk = s.getBytes("gbk");        raf.write(gbk);        System.out.println(raf.length());            //讀檔案必須把指標移動到頭部        raf.seek(0);                //一次性讀取        byte[] buf = new byte[(int)raf.length()];        raf.read(buf);        System.out.println(Arrays.toString(buf));        for(byte b:buf){            System.out.print(Integer.toHexString(b & 0xff)+"  ");        }        String s1 = new String(buf);        System.out.println(s1);                //關閉檔案        raf.close();        }}

 

RandomAccessFile類的使用(隨機讀取java中的檔案)