RandomAccessFile步骤使用测试

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();        	}}