让星星⭐月亮告诉你，Java NIO之Buffer详解 属性capacity/position/limit/mark 方法put(X)/get()/flip()/compact()/clear()

package nio;

import java.nio.ByteBuffer;

public class BufferTest {
    public static void main(String[] args) throws InterruptedException {
        ByteBuffer buf = ByteBuffer.allocate(9);
        System.out.println("初始capacity = " +buf.capacity());
        System.out.println("初始position = " + buf.position());
        System.out.println("初始limit = " + buf.limit());
        System.out.println("初始mark = " + buf.mark());
        buf.put("123456789".getBytes());
        System.out.println("put写之后的position = " + buf.position());
        System.out.println("put写之后的limit = " + buf.limit());
        System.out.println("put写之后的mark = " + buf.mark());

        buf.flip();//put写之后要flip,将position置为0,将limit置为写入的最后一个元素(待操作的下一个元素)所在的索引位置
        System.out.println("flip之后的position = " + buf.position());
        System.out.println("flip之后的limit = " + buf.limit());
        System.out.println("flip之后的mark = " + buf.mark());

        /*
        while(buf.hasRemaining()){
            System.out.println("#" + (char)buf.get());
        }
        System.out.println("get之后的position = " + buf.position());
        System.out.println("get之后的limit = " + buf.limit());
        System.out.println("get之后的mark = " + buf.mark());
        */

        for(int i = 0 ; i <= 3; i++ ){
            System.out.println("#" + (char)buf.get());
        }
        System.out.println("部分get读之后的position = " + buf.position());

        buf.compact();
        System.out.println("compact之后的position = " + buf.position());
        System.out.println("compact之后的limit = " + buf.limit());
        System.out.println("compact之后的mark = " + buf.mark());

        buf.put("abcd".getBytes());
        buf.flip();
        while(buf.hasRemaining()){
            System.out.println("#" + (char)buf.get());
        }

        buf.clear();
        System.out.println("clear之后的position = " + buf.position());
        System.out.println("clear之后的limit = " + buf.limit());
        System.out.println("clear之后的mark = " + buf.mark());
    }
}