RandomAccessFile方法使用测试

public class Test {public static void main(String[] args) throws IOException, InterruptedException {    test1();//    test2();    test3();}private static void test1() throws IOException{        String filePath = "F:/shanch/temp/a.txt";        //RandomAccessFile没有会自动创建文件    RandomAccessFile raFile = new RandomAccessFile(filePath,"rw");    System.out.println(raFile.getFilePointer());        //setLength会往文件里面写入空白串 即byte 00    raFile.setLength(36);        raFile.writeBytes("0123456789abcdefghijklmnopqrstuvwxyz1111");        System.out.println(raFile.getFilePointer());        //会将多出的1111截掉    raFile.setLength(36);    System.out.println(raFile.getFilePointer());        raFile.seek(20);    System.out.println(raFile.getFilePointer());        raFile.skipBytes(6);    System.out.println(raFile.getFilePointer());        //skipbytes不会使指针将超过文件长度    raFile.skipBytes(20);        System.out.println(raFile.getFilePointer());            //seek如果位置超过文件长度，会将文件扩大        raFile.seek(50);        System.out.println(raFile.getFilePointer());        raFile.write(100);                raFile.setLength(36);        }private static void test2() throws IOException{        String filePath = "F:/shanch/temp/a.txt";        RandomAccessFile raFile = new RandomAccessFile(filePath,"rw");                raFile.seek(10);        //read读取当前指针的byte 读取之后指针下移一个byte        System.out.println((char)raFile.read());        System.out.println(raFile.getFilePointer());                raFile.seek(10);        raFile.write(0);//替换a 而非插入        raFile.write(0);//替换b        raFile.write(0);//替换c}private static void test3() throws IOException, InterruptedException{     final String filePath = "F:/shanch/temp/a.txt";        RandomAccessFile raFile = new RandomAccessFile(filePath,"rw");        FileChannel fChannel = raFile.getChannel();        //当文件锁住时，不可修改//        fChannel.lock();        //程序退出时会自动释放锁                //position与FilePointer一致        fChannel.position(10);        System.out.println(raFile.getFilePointer());        raFile.seek(20);        System.out.println(fChannel.position());                //清空文件,从文件头开始,只保留指定字节数         fChannel.truncate(50);                fChannel.lock(10, 10, true);        //FileChannel与RandomAccessFile的写方法是不同的实现        //FileChannel锁住时,RandomAccessFile将不能写//        raFile.seek(15); //        raFile.write(97); //此处会报异常                Thread.currentThread().sleep(2000);        new Thread() {            public void run(){                try                {                    RandomAccessFile raFile = new RandomAccessFile(filePath,"rw");                    raFile.seek(15);                    System.out.println((char)raFile.read());                    raFile.write(26);//另一个程序已锁定文件的一部分，进程无法访问。//                    raFile.read();                }                catch (IOException e1)                {                    e1.printStackTrace();                }            }        }.start();        }}