发送文件时，你可以这样做ctx.writeAndFlush(new ChunkedFile(new File("file.png")));.
怎么样List<Object>?
该列表包含String and bytes of image.
从文档中有ChunkedInput()但我无法使用它。
UPDATE
让我们说在我的处理程序里面channelRead0(ChannelHandlerContext ctx, Object o)我想发送的方法List<Object>我已经做了以下操作
@Override
protected void channelRead0(ChannelHandlerContext ctx, Object o) throws Exception {
List<Object> msg = new ArrayList<>();
/**getting the bytes of image**/
byte[] imageInByte;
BufferedImage originalImage = ImageIO.read(new File(fileName));
// convert BufferedImage to byte array
ByteArrayOutputStream bAoS = new ByteArrayOutputStream();
ImageIO.write(originalImage, "png", bAoS);
bAoS.flush();
imageInByte = baos.toByteArray();
baos.close();
msg.clear();
msg.add(0, "String"); //add the String into List
msg.add(1, imageInByte); //add the bytes of images into list
/**Chunk the List<Object> and Send it just like the chunked file**/
ctx.writeAndFlush(new ChunkedInput(DONT_KNOW_WHAT_TO_DO_HERE)); //
}
只需实现您自己的ChunkedInput<ByteBuf>。按照 Netty 附带的实现，您可以按如下方式实现它：
public class ChunkedList implements ChunkedInput<ByteBuf> {
private static final byte[] EMPTY = new byte[0];
private byte[] previousPart = EMPTY;
private final int chunkSize;
private final Iterator<Object> iterator;
public ChunkedList(int chunkSize, List<Object> objs) {
//chunk size in bytes
this.chunkSize = chunkSize;
this.iterator = objs.iterator();
}
public ByteBuf readChunk(ChannelHandlerContext ctx) {
return readChunk(ctx.alloc());
}
public ByteBuf readChunk(ByteBufAllocator allocator) {
if (isEndOfInput())
return null;
else {
ByteBuf buf = allocator.buffer(chunkSize);
boolean release = true;
try {
int bytesRead = 0;
if (previousPart.length > 0) {
if (previousPart.length > chunkSize) {
throw new IllegalStateException();
}
bytesRead += previousPart.length;
buf.writeBytes(previousPart);
}
boolean done = false;
while (!done) {
if (!iterator.hasNext()) {
done = true;
previousPart = EMPTY;
} else {
Object o = iterator.next();
//depending on the encoding
byte[] bytes = o instanceof String ? ((String) o).getBytes() : (byte[]) o;
bytesRead += bytes.length;
if (bytesRead > chunkSize) {
done = true;
previousPart = bytes;
} else {
buf.writeBytes(bytes);
}
}
}
release = false;
} finally {
if (release)
buf.release();
}
return buf;
}
}
public long length() {
return -1;
}
public boolean isEndOfInput() {
return !iterator.hasNext() && previousPart.length == 0;
}
public long progress() {
return 0;
}
public void close(){
//close
}
}
为了写ChunkedContent附带有一个特殊的处理程序Netty. See io.netty.handler.stream.ChunkedWriteHandler。所以只需添加到您的下游即可。这是文档中的引用：
A ChannelHandler增加了对写入大数据流的支持
异步既不消耗大量内存也不获取OutOfMemoryError。文件传输等大数据流需要
复杂的状态管理ChannelHandler执行。ChunkedWriteHandler管理如此复杂的状态，以便您可以
毫无困难地发送大数据流。
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