public BufferedReader(Reader in) {
 // private static int defaultCharBufferSize = 8192;
 // 内部维护了一个字符数组
    // private char cb[];
    this(in, defaultCharBufferSize);
}
public BufferedWriter(Writer out) {
        this(out, defaultCharBufferSize);
}

// 创建流对象
BufferedReader br = new BufferedReader(new FileReader("D:/三国/赵云.txt"));
BufferedWriter bw = new BufferedWriter(new FileWriter("D:/三国/赵子龙.txt"));
String line = null;
while ((line = br.readLine())!=null) {
  System.out.println(line);
  bw.write(line);
  bw.newLine();
}
// 结果
我乃常山赵子龙
于万军从中，取上将首级

BufferedInputStream bis = null;
BufferedOutputStream bos = null;
try {
    bis = new BufferedInputStream(new FileInputStream(new File("D:/三国/视频.mp4")));
    bos = new BufferedOutputStream(new FileOutputStream(new File("D:/三国/拷贝.mp4")));
    int len;
    // 一次传输8M的文件,实际测试这里传输的大小并不影响传输的速度
    byte[] data = new byte[8 * 1024];
    while ((len = bis.read(data)) != -1) {
        bos.write(data, 0, len);
    }
} catch (IOException e) {
    log.error("error", e);
} finally {
   // finally块中关闭流，确保资源一定被关闭
    if (bis != null) {
        try {
            bis.close();
        } catch (IOException e) {
            log.error("error", e);
        }
    }
    if (bos != null) {
        try {
            bos.close();
        } catch (IOException e) {
            log.error("error", e);
        }
    }
}

FileReader fileReader = new FileReader("D:/sanguo/utf8.txt");
int read;
while ((read = fileReader.read()) != -1) {
    System.out.print((char)read);
}
// 浣犲ソ

// 使用平台默认字符集
public InputStreamReader(InputStream in) {}
// 指定字符集
public InputStreamReader(InputStream in, String charsetName)
        throws UnsupportedEncodingException{}

// 创建流对象,默认UTF8编码
InputStreamReader isr = new InputStreamReader(new FileInputStream("D:/三国/utf8.txt"));
// 创建流对象,指定GBK编码
InputStreamReader isr2 = new InputStreamReader(new FileInputStream("D:/三国/utf8.txt"), "GBK");
int read;
while ((read = isr.read()) != -1) {
    System.out.println((char) read);
}
while ((read = isr2.read()) != -1) {
    System.out.println((char) read);
}
// 输出结果
你好
浣犲ソ

// 使用平台默认字符集
public OutputStreamWriter(OutputStream out) {}
// 使用平台默认字符集
public OutputStreamWriter(OutputStream out, String charsetName)
throws UnsupportedEncodingException{}

// 创建流对象,默认UTF8编码
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("D:/三国/黄忠.txt"));
osw.write("你好"); // 保存为6个字节
// 创建流对象,指定GBK编码
OutputStreamWriter osw2 = new OutputStreamWriter(new FileOutputStream("D:/三国/马超.txt"),"GBK");
osw2.write("你好");// 保存为4个字节

public ObjectOutputStream(OutputStream out) throws IOException{}

public class User implements Serializable {
    private static final long serialVersionUID = 8289102797441171947L;
    private String name;
    private Integer age;
}
// 下面是将对象输出到文件的核心代码
User user = new User("马超",20);
// 创建序列化流对象
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("D:/三国/马超.txt"));
// 写出对象
out.writeObject(user);

public ObjectInputStream(InputStream in) throws IOException

ObjectInputStream in = new ObjectInputStream(new FileInputStream("D:/三国/马超.txt"));
// 强转为user
User user = (User) in.readObject();
System.out.println(user);
// 输出内容
User(name=马超, age=20)

// 将对象转为byte[]
public static <T> byte[] t1(T t) {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bos);
    oos.writeObject(t);
    return bos.toByteArray();
}
// 将byte[]转为对象
public static <T> T t2(byte[] data) throws IOException, ClassNotFoundException {
    ByteArrayInputStream bos = new ByteArrayInputStream(data);
    ObjectInputStream oos = new ObjectInputStream(bos);
    return (T) oos.readObject();
}

class Sender implements Runnable {
    private PipedOutputStream pos;
    private String msg;
    public Sender(String msg) {
        this.pos = new PipedOutputStream();
        this.msg = msg;
    }
    @Override
    public void run() {
       pos.write(msg.getBytes())；
    }
    public PipedOutputStream getPos() {
        return pos;
    }
}
class Receiver implements Runnable {
    private PipedInputStream pis;
    public Receiver() {
        this.pis = new PipedInputStream();
    }
    @Override
    public void run() {
         byte[] data = new byte[1024];
            int len;
            while ((len = pis.read(data)) != -1) {
                System.out.println(new String(data, 0, len));
            }
    }
}
Sender sender = new Sender("hello");
Receiver receiver = new Receiver();
receiver.getPis().connect(sender.getPos());
new Thread(sender).start();
new Thread(receiver).start();
// 控制台输出  hello

System.out.println("a");
System.out.print("b");
class System{
    public final static InputStream in = null;
    public final static PrintStream out = null;
}
public PrintStream(String fileName) throws FileNotFoundException{}

DataOutputStream dos = new DataOutputStream(new FileOutputStream("D:/三国/周瑜.txt"));
dos.writeUTF("周瑜");
dos.writeBoolean(false);
dos.writeLong(1234567890L);
DataInputStream dis = new DataInputStream(new FileInputStream("D:/三国/周瑜.txt"));
String s = dis.readUTF();
System.out.println(s);
boolean b = dis.readBoolean();
System.out.println(b);
// 输出
周瑜
false