Netty中的Unpooled.buffer

1.介绍

　　ByteBuf是Netty的数据容器对象；

　　Unpooled是操作数据容器的工具类；

 

2.指针

　　进行readByte和writeByte方法的调用时会改变readIndex和writeIndex的值，而调用set和get方法时不会改变readIndex和writeIndex的值。上面的测试案例中打印的writeIndex和readIndex均为1,并未在调用set和get方法后被改变。

    public static void main(String[] args) {
        ByteBuf heapBuf = Unpooled.buffer(5);
        heapBuf.writeByte(1);
        System.out.println("writeIndex : " + heapBuf.writerIndex());   //writeIndex : 1
        heapBuf.readByte();
        System.out.println("readIndex : " + heapBuf.readerIndex());   //readIndex : 1
        heapBuf.setByte(2, 6);
        System.out.println("writeIndex : " + heapBuf.writerIndex());  //writeIndex : 1
        heapBuf.getByte(2);
        System.out.println("readIndex : " + heapBuf.readerIndex());   //readIndex : 1

        for (int i = 0; i < heapBuf.capacity(); i++) {
            System.out.println(heapBuf.getByte(i));
        }
    }

　　效果

writeIndex : 1
readIndex : 1
writeIndex : 1
readIndex : 1
1
0
6
0
0
Disconnected from the target VM, address: '127.0.0.1:62437', transport: 'socket'

 

3.String转为ByteBuf

    public static void main(String[] args) {
        ByteBuf buffer = Unpooled.copiedBuffer("hello,word!", Charset.forName("utf-8"));
        if (buffer.hasArray()) {
            byte[] array = buffer.array();
            System.out.println(new String(array, Charset.forName("utf-8")));
            System.out.println("byteBuf=" + buffer);
            System.out.println(buffer.arrayOffset());
            System.out.println(buffer.readerIndex());
            System.out.println(buffer.writerIndex());
            System.out.println(buffer.capacity());

            int len = buffer.readableBytes(); //可读的字节数
            System.out.println("len=" + len);
            for (int i = 0; i < len; i++) {
                System.out.println((char) buffer.getByte(i));
            }

            System.out.println(buffer.getCharSequence(0, 4, Charset.forName("utf-8")));
            System.out.println(buffer.getCharSequence(4, 1, Charset.forName("utf-8")));
        }
    }

　　效果

hello,word!                      
byteBuf=UnpooledUnsafeHeapByteBuf(ridx: 0, widx: 11, cap: 33)
0
0
11
33
len=11
h
e
l
l
o
,
w
o
r
d
!
hell
o

Process finished with exit code 0