一、接口繼承圖
二、接口類功能概述和實現
DataBuffer是對java NIO中的ByteBuffer 和Netty的ByteBuf 的統一包裝,包含對字節緩衝區操作的各種方法,如下:
DefaultDataBuffer是DataBuffer的默認實現,基於java NIO的ByteBuffer實現, 相關ByteBuffer的操作參考:
https://blog.csdn.net/shuaiAWP/article/details/51915983
PooledDataBuffer繼承DataBuffer接口,增加了引用計數的方法,保留方法將引用計數增加1。 釋放方法將計數減1,並在計數達到0時釋放緩衝區的內存,增加的方法如下:
NettyDataBuffer是PooledDataBuffer的唯一實現,基於Netty 的ByteBuf實現。
DataBufferFactory接口提供了用於構造DataBuffer的方法,如下所示:
其中join方法用於將多個DataBuffer做合併處理。DefaultDataBufferFactory是DefaultDataBuffer的工廠類,NettyDataBufferFactory是NettyDataBuffer的工廠類。
DataBufferUtils是DataBuffer接口的工具類,它包含從InputStream或NIO通道讀取DataBuffer對象的Flux的方法,以及將數據緩衝區Flux寫入OutputStream或Channel的方法等。但是該工具類是基於反應式編程框架Reactor中的Flux元素寫的,Reactor參考如下:https://www.ibm.com/developerworks/cn/java/j-cn-with-reactor-response-encode/index.html?lnk=hmhm
參考測試用例如下:
@Test
public void writeAndRead() throws Exception{
DataBufferFactory dataBufferFactory=new DefaultDataBufferFactory();
DataBuffer buffer = dataBufferFactory.allocateBuffer(2);
buffer.write(new byte[]{'a', 'b', 'c'});
System.out.println("capacity-->"+buffer.capacity());
System.out.println("readPosition-->"+buffer.readPosition());
System.out.println("writePosition-->"+buffer.writePosition());
System.out.println("writableByteCount-->"+buffer.writableByteCount());
System.out.println("readableByteCount-->"+buffer.readableByteCount());
int index=buffer.indexOf(p -> p=='c', 1);
System.out.println("index-->"+index);
int ch = buffer.read();
assertEquals('a', ch);
buffer.readPosition(2);
ch = buffer.read();
assertEquals('c', ch);
buffer.write((byte) 'd');
buffer.write((byte) 'e');
byte[] result = new byte[2];
buffer.read(result);
assertArrayEquals(new byte[]{'d', 'e'}, result);
ByteBuffer buffer2=ByteBuffer.allocate(4);
buffer2.put((byte) '1');
buffer2.put((byte) '2');
buffer2.put((byte) '3');
buffer2.put((byte) '4');
buffer2.position(2);
System.out.println("write before writePosition-->"+buffer.writePosition());
buffer.write(buffer2);
System.out.println("write after writePosition-->"+buffer.writePosition());
ByteBuffer buffer3=buffer.asByteBuffer(4, 5);
ch = buffer3.get();
assertEquals('e', ch);
assertEquals(5,buffer3.limit());
InputStream in=buffer.asInputStream();
in.read(result);
assertArrayEquals(new byte[]{'3', '4'}, result);
DataBufferUtils.release(buffer);
}
@Test
public void retainAndRelease() {
NettyDataBufferFactory dataBufferFactory=new NettyDataBufferFactory(new PooledByteBufAllocator());
PooledDataBuffer buffer = dataBufferFactory.allocateBuffer(4);
// buffer.write((byte) 'a');
buffer.retain();
boolean result = buffer.release();
assertFalse(result);
result = buffer.release();
assertTrue(result);
}