java-ioStream

/** ioStream
 * 从传输方式上分为：字节流(InputStream、OutputStream)、字符流(Reader、Writer)
 * 从数据操作上分为：文件、数组、管道操作、基本数据类型、缓冲操作、打印、对象序列化反序列化、转换
 *
 * 字节流读取单个字节、字符流读取单个字符
 * 字节流用来处理二进制文件（图片、mp3..），字符流用来处理文本文件
 * 编码就是把字符转换为字节，解码则相反
 */

public class ioStreamExample {

    // 装饰者模式，BufferedInputStreamz装饰fileInputStream
    public void decorator_method() throws FileNotFoundException {
        FileInputStream fileInputStream = new FileInputStream("");
        FileOutputStream fileOutputStream  =new FileOutputStream("");
        BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream);
    }

    // IO-磁盘操作：File
    public void listAllFiles(File dir){
        if (dir == null || !dir.exists()){
            return;
        }if (dir.isFile()){
            System.out.println(dir.getName());
            return;
        }
        // 递归地列出一个目录下所有文件
        for (File file: Objects.requireNonNull(dir.listFiles())){
            listAllFiles(file);
        }
    }

    // IO-字节操作：(InputStream和OutputStream)拷贝文件内容
    public void copyFile(String src,String dst) throws IOException {
        FileInputStream fi = new FileInputStream(src);
        FileOutputStream fo = new FileOutputStream(dst);
        byte[] buf = new byte[20 * 1024];
        while (fi.read(buf,0,buf.length) != -1){
            fo.write(buf);
        }

        fi.close();
        fo.close();
    }

    // IO-字符操作：(Reader和Writer)输出文件内容
    public void readFileContent(String filePath) throws IOException {
        FileReader fileReader = new FileReader(filePath);
        BufferedReader bufferedReader = new BufferedReader(fileReader);
        String line = "";
        while ((line = bufferedReader.readLine()) != null){
            System.out.println(line);
        }

        bufferedReader.close();
    }

    // IO-对象操作：序列化。序列化的类需要实现Serializable接口
    /**序列化：将一个对象转换成字节序列，方便存储和传输
     * 序列化：ObjectOutputStream.writeObject()
     * 反序列化：ObjectInputStream.readObject()
     */
    public void serializableExample(String filePath) throws IOException, ClassNotFoundException {
        A a = new A(100,"y");
        ObjectOutputStream oo = new ObjectOutputStream(new FileOutputStream(filePath));
        oo.writeObject(a);
        oo.close();

        ObjectInputStream oi = new ObjectInputStream(new FileInputStream(filePath));
        A a1 = (A) oi.readObject();
        oi.close();
        System.out.println(a1);

    }

    // IO-网络操作：(socket)
    /** Sockets:使用tcp协议实现网络通信
     *      ServerSocket:服务端类，Socket：客户端类。服务端和客户端通过InputStream和OutputStream进行输入输出
     *  Datagram：使用udp协议实现网络通信
     *      DatagramSocket：通信类，DatagramPacket：数据包类
     */
    public void socketExample() throws IOException {
        URL url = new URL("http://www.baidu.com");
        InputStream is = url.openStream();      // 字节流
        InputStreamReader isr = new InputStreamReader(is,"utf-8");      // 字符流
        BufferedReader br = new BufferedReader(isr);        // 提供缓存功能
        String line;
        while ((line = br.readLine()) != null){
            System.out.println(line);
        }
        br.close();
    }

    public static void main(String[] args) throws IOException, ClassNotFoundException {
        String file = "D:\\oldfile.txt";
        ioStreamExample ioStreamExample = new ioStreamExample();

//        ioStreamExample.serializableExample(file);
//        ioStreamExample.readFileContent(file);

        ioStreamExample.socketExample();

    }

}

@Data
@AllArgsConstructor
@NoArgsConstructor
class A implements Serializable{
    private int x;
    private String y;
}