java各种流的常见使用方法及示例

import java.io.*;

public class FileCopy {
    public static void main(String[] args) {
        try (InputStream in = new FileInputStream("source.jpg");
             OutputStream out = new FileOutputStream("copy.jpg")) {
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            System.out.println("文件复制完成！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class BufferedRead {
    public static void main(String[] args) {
        try (FileInputStream fis = new FileInputStream("data.bin");
             BufferedInputStream in = new BufferedInputStream(fis)) {
            int data;
            while ((data = in.read()) != -1) {
                // 处理每个字节 data
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class DataStreamDemo {
    public static void main(String[] args) {
        try (DataOutputStream dos = new DataOutputStream(new FileOutputStream("data.dat"))) {
            dos.writeInt(100);
            dos.writeDouble(3.14);
            dos.writeBoolean(true);
            dos.writeUTF("你好");
        } catch (IOException e) {
            e.printStackTrace();
        }

        try (DataInputStream dis = new DataInputStream(new FileInputStream("data.dat"))) {
            int i = dis.readInt();
            double d = dis.readDouble();
            boolean b = dis.readBoolean();
            String s = dis.readUTF();
            System.out.println(i + ", " + d + ", " + b + ", " + s);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

class Person implements Serializable {
    private String name;
    private transient int age; // transient 修饰的字段不会被序列化

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    // ... Getters, Setters, toString ...
}

public class ObjectStreamDemo {
    public static void main(String[] args) {
        Person person = new Person("张三", 30);
        try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("person.dat"))) {
            oos.writeObject(person);
        } catch (IOException e) {
            e.printStackTrace();
        }

        try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream("person.dat"))) {
            Person readPerson = (Person) ois.readObject();
            System.out.println(readPerson); // 注意 age 字段为默认值 0 (未序列化)
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class FileReadWrite {
    public static void main(String[] args) {
        try (Reader reader = new FileReader("input.txt");
             Writer writer = new FileWriter("output.txt")) {
            char[] buffer = new char[1024];
            int charsRead;
            while ((charsRead = reader.read(buffer)) != -1) {
                writer.write(buffer, 0, charsRead);
            }
            System.out.println("文本文件复制完成！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class BufferedReaderDemo {
    public static void main(String[] args) {
        try (BufferedReader br = new BufferedReader(new FileReader("input.txt"))) {
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class EncodingDemo {
    public static void main(String[] args) {
        try (InputStream fis = new FileInputStream("input_gbk.txt");
             // 将字节流 fis 转换为字符流，并指定编码为 GBK
             Reader isr = new InputStreamReader(fis, "GBK");
             BufferedReader br = new BufferedReader(isr)) {
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line); // 正确显示 GBK 编码的中文
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class PrintWriterDemo {
    public static void main(String[] args) {
        try (PrintWriter pw = new PrintWriter(new FileWriter("log.txt"))) {
            pw.println("日志开始:");
            pw.printf("时间: %tT%n", System.currentTimeMillis());
            pw.println("操作: 用户登录");
            pw.println("日志结束.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;

public class PipedStreamDemo {
    public static void main(String[] args) throws IOException {
        PipedOutputStream pos = new PipedOutputStream();
        PipedInputStream pis = new PipedInputStream(pos); // 连接管道

        Thread writerThread = new Thread(() -> {
            try (DataOutputStream dos = new DataOutputStream(pos)) {
                dos.writeUTF("Hello from writer thread!");
            } catch (IOException e) {
                e.printStackTrace();
            }
        });

        Thread readerThread = new Thread(() -> {
            try (DataInputStream dis = new DataInputStream(pis)) {
                String message = dis.readUTF();
                System.out.println("Reader thread received: " + message);
            } catch (IOException e) {
                e.printStackTrace();
            }
        });

        writerThread.start();
        readerThread.start();
    }
}