处理流：BufferedInputStream/Reader BufferesOutputStream/Writer
注意：当使用处理流输出时，需要使用flush来刷新流
1.使用节点流从磁盘将数据读取到内存的缓存区
2.将内存缓冲区的数据读取到处理流对应的缓冲区
3.处理流从处理流的缓冲区将数据读取

输入输出重定向 System.out -> 终端（重定向到自己的文件里面）

如果需要将自己定义的类的某个对象使用文件保存，那么这个类必须是实现了Seria;izable接口

MyClass.java

public class MyClass {
    public static void main(String[] agrs) {
        
    } 
}

//字符操作
public static void buffered_io(String src, String des){
    try {
        //创建输入流
        FileInputStream fis = new FileInputStream(src);
        InputStreamReader isr = new InputStreamReader(fis);
        BufferedReader br = new BufferedReader(isr);
        //创建输出流
        FileOutputStream fos = new FileOutputStream(des);
        OutputStreamWriter osw = new OutputStreamWriter(fos);
        BufferedWriter bw = new BufferedWriter(osw);

        int ch = 0;
        //初级写法
//      while (true) {
//          ch = br.read();
//          if (ch == -1){
//              break;
//          }
//          bw.writer(ch);
//      }

        //进阶写法
        while((ch = br. read()) != -1){
            bw.writer(ch);
        }
        
        bf.flush();

    } catch (Exception e) {
        e.printStackTrace();
    }
}

//字节操作
public static void buffered_io_by(String src2, String des2){
    try {
        //字节缓冲输入流
        FileInputStream fis2 = new FileInputStream(src2);
        BufferedInputStream bis2 = new FileInputStream(fis2);

        //字节缓冲输出流
        FileOutputStream fos = new FileOutputStream(des2);
        BufferedOutputStream bos = new BufferedOutputStream(fos);

        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = bis2.read(buffer)) != -1){
            bos.write(buffer);
        }
        
        bf.flush();

    } catch (Exception e) {
        e.printStackTrace();
    }
}   

//输入重定向
public static void redirect_in(String src3){
    try {
        FileInputStream fis3 = new FileInputStream(src3);
        Scanner scanner = new Scanner(fis3);
        System.out.println(scanner.next());
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
}

//输入输出重定向
public static void redirect_out(String des3){
    try {
        PrintStream ps = new PrintStream(new FileOutputStream(des3));
        System.setOut(ps);
        
    } catch (Exception e) {
        e.printStackTrace();
    }
}


//保存对象
public static void saveObject(String des4){
    try {
        FileOutputStream fos = new FileOutputStream(des4);
        ObjectOutputStream oos = new ObjectOutputStream(fos4);

        Person p = new Person(name: "jack", age: 23);
        oos.writeObject(p);

    } catch (Exception e) {
        e.printStackTrace();
    }
}

//读取对象
public static void readObject(String src4){
    try {
        FileInputStream fis = new FileInputStream(src4);
        ObjectInputStream ois = new ObjectInputStream(fis4);

         Person p = (Person) ois.readObject();
 
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Person.java

public class Person implements Serializable {
    String name;
    int age;

    pubilc Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString90 {
        return "Person{" +
            "name='" + name + '\'' +
            ", age=" + age +
            '}';
    }
}