Created
August 28, 2018 18:45
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ReplayingDecoder to read a sequence of uploaded files
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/** | |
* | |
*/ | |
package net.example; | |
import java.nio.charset.Charset; | |
import java.util.List; | |
import io.netty.buffer.ByteBuf; | |
import io.netty.channel.ChannelHandlerContext; | |
import io.netty.handler.codec.ReplayingDecoder; | |
public class FileUploadReplayingDecoder extends ReplayingDecoder<FileUploadReplayingDecoder.FileUploadField> { | |
public static final Charset UTF8 = Charset.forName("UTF8"); | |
protected int fileNumber = -1; | |
protected int filesRead = 0; | |
protected int nextSize = -1; | |
protected int nameSize = -1; | |
protected byte[] nameBytes = null; | |
protected String fileName = null; | |
public FileUploadReplayingDecoder() { | |
super(FileUploadField.NUMBER); | |
} | |
public static class Upload { | |
public String fileName = null; | |
public ByteBuf content = null; | |
Upload(String fileName, ByteBuf content) { | |
super(); | |
this.fileName = fileName; | |
this.content = content; | |
} | |
} | |
public static enum FileUploadField { | |
NUMBER, | |
SIZE, | |
NAME_SIZE, | |
NAME, | |
CONTENT; | |
} | |
@Override | |
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception { | |
switch(state()) { | |
case NUMBER: | |
fileNumber = in.readInt(); | |
checkpoint(FileUploadField.SIZE); | |
case SIZE: | |
nextSize = in.readInt(); | |
checkpoint(FileUploadField.NAME_SIZE); | |
case NAME_SIZE: | |
nameSize = in.readInt(); | |
nameBytes = new byte[nameSize]; | |
checkpoint(FileUploadField.NAME); | |
case NAME: | |
in.readBytes(nameBytes); | |
fileName = new String(nameBytes, UTF8); | |
checkpoint(FileUploadField.CONTENT); | |
case CONTENT: | |
// Need to ReferenceCountUtil.release(fileContent) after use. | |
ByteBuf fileContent = in.readBytes(nextSize); | |
out.add(new Upload(fileName, fileContent)); | |
filesRead++; | |
if(filesRead == fileNumber) { | |
ctx.pipeline().remove(this); | |
} else { | |
checkpoint(FileUploadField.SIZE); | |
} | |
break; | |
default: | |
throw new Error("Shouldn't reach here."); | |
} | |
} | |
} |
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