1 package FileDemo; 2  3 import java.io.IOException; 4 import java.io.RandomAccessFile; 5  6 public class RandomAccessFileDemo { 7  8     /** 9      * @param args10      * @throws IOException11      */12     public static void main(String[] args) throws IOException {13 14         writeAccess();15         readAccess();16         randomWrite();17     }18 19     // 随机写入数据，可以实现对已有数据的修改,因为可以使用seek()方法改变文件指针的位置20     private static void randomWrite() throws IOException {21         RandomAccessFile raf = new RandomAccessFile("random.txt", "rw");22         raf.seek(8 * 4);//将文件指针移动到指定位置23         System.out.println(raf.getFilePointer());24         raf.write("Ruby".getBytes());25         raf.writeInt(99);26     }27 28     private static void readAccess() throws IOException {29         RandomAccessFile raf = new RandomAccessFile("random.txt", "r");30         System.out.println(raf.getFilePointer());31         raf.seek(8);// 用于实现随机读取文件中的数据，数据最号有规律32         System.out.println(raf.getFilePointer());33         byte buf[] = new byte[4];34         raf.read(buf);35         String name = new String(buf);36         int age = raf.readInt();37         System.out.println("name=" + name);38         System.out.println("age=" + age);39         System.out.println(raf.getFilePointer());40 41     }42 43     private static void writeAccess() throws IOException {44         // rw:当这个文件不存在，会创建文件，当文件已经存在，不会创建，所以不会出现和输出流一样的覆盖45         RandomAccessFile raf = new RandomAccessFile("random.txt", "rw");46         raf.write("Java".getBytes());47         raf.writeInt(97);48         raf.write("python".getBytes());49         raf.write(98);50         raf.close();51     }52 53 }