RandomAccessFile

    // 文本文件的复制（实现读写）
	@Test
	public void test1() {
		RandomAccessFile rafin = null;
		RandomAccessFile rafout = null;
		try {
			rafin = new RandomAccessFile("C:/Users/59929/Desktop/test1.txt", "r");
			rafout = new RandomAccessFile("C:/Users/59929/Documents/test.txt", "rw");
			int len;
			byte[] b = new byte[1024];
			while ((len = rafin.read(b)) != -1) {
				rafout.write(b, 0, len);
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (rafout != null) {
				try {
					rafout.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if (rafin != null) {
				try {
					rafin.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
	// 实现文本文件的插入操作
	@Test
	public void test2() {
		RandomAccessFile raf = null;
		try {
			raf = new RandomAccessFile("C:/Users/59929/Desktop/test2.txt", "rw");
			System.out.println("现在指针位置为：" + raf.getFilePointer());
			raf.seek(16);
			System.out.println("移到要修改的位置，现在指针位置为：" + raf.getFilePointer());
			int len;
			byte[] b = new byte[10];
			StringBuffer sb = new StringBuffer();
			while ((len = raf.read(b)) != -1) {
				sb.append(new String(b, 0, len));
			}
			System.out.println("读完后现在指针位置为：" + raf.getFilePointer());
			raf.seek(16);
			System.out.println("再次移到要修改的位置，现在指针位置为：" + raf.getFilePointer());
			raf.write("c".getBytes());
			raf.write(sb.toString().getBytes());
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (raf != null) {
				try {
					raf.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}