java IO流的其他一些流

1、SequenceInputStream(序列流)

/**
 * 序列流整合多个	
 * @param args
 * @throws Exception 
 */
	public static void main(String[] args) throws Exception {
		FileInputStream s1 = new FileInputStream("a.txt");
		FileInputStream s2 = new FileInputStream("b.txt");
		FileInputStream s3 = new FileInputStream("c.txt");
		
		FileOutputStream fos = new FileOutputStream("d.txt");
		
		Vector<FileInputStream> v = new Vector<>();
		v.add(s1);
		v.add(s2);
		v.add(s3);
		
		Enumeration<FileInputStream> en = v.elements();
		
		SequenceInputStream sis = new SequenceInputStream(en);
		
		int b;
		while((b = sis.read()) != -1) {
			fos.write(b);
		}
		fos.close();
		sis.close();
		
	}

2、ByteArrayOutputStream:内存输出流

FileInputStream fis = new FileInputStream("a.txt");
		/**
		 * 在内存中创建了可以增长的字节数组
		 */
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		int b;
		while((b = fis.read()) != -1) {
			baos.write(b);
		}
		/**
		 * 将缓冲区的数据全部获取 赋值给arr
		 */
		//1,new String()可以指定编码表
		byte[] arr = baos.toByteArray();
		System.out.println(new String(arr));
		//2,不能制定编码表
		System.out.println(baos.toString());
		
		fis.close();

3、ByteArrayOutputStream：内存输出流

FileInputStream fis = new FileInputStream("d:\\iotest\\2.txt");
		byte[] arr = new byte[5];
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		
		int len;
		while((len = fis.read(arr)) != -1) {
			baos.write(arr, 0, len);
		}
		System.out.println(baos);
		fis.close();

4、序列化和反序列化

（public class Person implements Serializable）

public static void main(String[] args) throws Exception, IOException {
		Person p1 = new Person("p1",1);
		Person p2 = new Person("p1",2);
		Person p3 = new Person("p1",3);
		Person p4 = new Person("p1",4);
		Person p5 = new Person("p1",5);
		
		ArrayList<Person> list = new ArrayList<>();
		list.add(p1);
		list.add(p2);
		list.add(p3);
		list.add(p4);
		list.add(p5);
		
		/**
		 * 序列化(存储数据到文件)
		 */
		ObjectOutputStream oos = 
				new ObjectOutputStream(new FileOutputStream("1.txt"));
		oos.writeObject(list);
		oos.close();
		/**
		 * 反序列化(读取文件)
		 */
		ObjectInputStream ois = 
				new ObjectInputStream(new FileInputStream("1.txt"));
		
		ArrayList<Person> al = (ArrayList<Person>) ois.readObject();
		
		for(Person p : al) {
			System.out.println(p);
		}
		
		
	}
	/**
	 * 反序列化：读取数据
	 * @throws Exception
	 */
	@SuppressWarnings({ "resource", "unused" })
	private static void demo()  throws Exception{
		ObjectInputStream ois = 
				new ObjectInputStream(new FileInputStream("e.txt"));
		
		Person p1 = (Person) ois.readObject();
		Person p2 = (Person) ois.readObject();
		//若出现第三个对象  EOFException!
		
		System.out.println(p1+","+p2);
	}

5、小程序：遍历某个文件夹上所有的.mp3文件，然后拼接

	@SuppressWarnings("resource")
	public static void main(String[] args) throws Exception {
		String path = "d:\\f";
		ArrayList<String> list = new ArrayList<>();
		getDir(new File(path),list);
		/**
		 * 文件拼接
		 */
		
		FileInputStream[] fArr = new FileInputStream[list.size()];
		Vector<FileInputStream> v = new Vector<>();
		
		for (int i = 0; i < list.size(); i++) {
			fArr[i] = new FileInputStream(path + "\\" + list.get(i));
			v.add(fArr[i]);
		}
		
		
		Enumeration<FileInputStream> en = v.elements();
		SequenceInputStream sis = new SequenceInputStream(en);
		
		FileOutputStream fos = new FileOutputStream("d:\\succ.mp3");
		
		int b;
		while((b = sis.read()) != -1) {
			fos.write(b);
		}
		
		fos.close();
		for (int i = 0; i < list.size(); i++) {
			fArr[i].close();
		}
		
	}
/**
 * 获取mp3文件
 * @param file
 * @param list
 */
	private static void getDir(File file,ArrayList<String> list) {
		File[] arr = file.listFiles();//获取文件数组
		for(File f : arr) {
			if(f.isFile() && f.getName().endsWith(".mp3")) {
				list.add(f.getName());
			} else if (f.isDirectory()){
				getDir(f,list);
			}
		}
	}