Netty：NIO buffer 原理（附 示例代码）

public class BufferTest {
    public static void main(String[] args) {
        CharBuffer charBuffer = CharBuffer.allocate(8);
        System.out.println("=========初始化");
        System.out.println("capacity:" + charBuffer.capacity());
        System.out.println("position:" + charBuffer.position());
        System.out.println("limit:" + charBuffer.limit());
 
        System.out.println("=========存储");
        charBuffer.put('h');
        charBuffer.put('y');
        charBuffer.put('c');
        System.out.println("position:" + charBuffer.position());
        System.out.println("limit:" + charBuffer.limit());
 
        charBuffer.flip();
        System.out.println("=========调用flip");
        System.out.println("position:" + charBuffer.position());
        System.out.println("limit:" + charBuffer.limit());
 
        System.out.println("=========读取数据");
        //没有参数就是读取第一个，且会用 position 记录
        //有参数 不会使用position记录
        //System.out.println(charBuffer.get());
        //System.out.println(charBuffer.get(1));
        //遍历方法
        //while (charBuffer.hasRemaining()) {
        //    System.out.println(charBuffer.get());
        //}
        //标记
        charBuffer.mark();
        System.out.println(charBuffer.get());
        System.out.println("position:" + charBuffer.position());
 
        System.out.println(charBuffer.get());
        System.out.println("position:" + charBuffer.position());
 
        //回退到标记的 position
        charBuffer.reset();
        System.out.println("========调用reset方法");
        System.out.println(charBuffer.get());
        System.out.println("position:" + charBuffer.position());
        System.out.println("limit:" + charBuffer.limit());
 
        charBuffer.clear();
        System.out.println("=========调用clear");
        System.out.println("position:" + charBuffer.position());
        System.out.println("limit:" + charBuffer.limit());
    }
}