http://netty.io/netty-all/: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers and clients. (The Netty Project) 
public class io.netty.handler.codec.LengthFieldPrepender extends io.netty.handler.codec.MessageToMessageEncoder<io.netty.buffer.ByteBuf>
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: io.netty.handler.codec.LengthFieldPrepender
  super_class: io.netty.handler.codec.MessageToMessageEncoder
{
  private final java.nio.ByteOrder byteOrder;
    descriptor: Ljava/nio/ByteOrder;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final int lengthFieldLength;
    descriptor: I
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final boolean lengthIncludesLengthFieldLength;
    descriptor: Z
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final int lengthAdjustment;
    descriptor: I
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  public void <init>(int);
    descriptor: (I)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // io.netty.handler.codec.LengthFieldPrepender this
        start local 1 // int lengthFieldLength
         0: .line 71
            aload 0 /* this */
            iload 1 /* lengthFieldLength */
            iconst_0
            invokespecial io.netty.handler.codec.LengthFieldPrepender.<init>:(IZ)V
         1: .line 72
            return
        end local 1 // int lengthFieldLength
        end local 0 // io.netty.handler.codec.LengthFieldPrepender this
      LocalVariableTable:
        Start  End  Slot               Name  Signature
            0    2     0               this  Lio/netty/handler/codec/LengthFieldPrepender;
            0    2     1  lengthFieldLength  I
    MethodParameters:
                   Name  Flags
      lengthFieldLength  

  public void <init>(int, boolean);
    descriptor: (IZ)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=3, args_size=3
        start local 0 // io.netty.handler.codec.LengthFieldPrepender this
        start local 1 // int lengthFieldLength
        start local 2 // boolean lengthIncludesLengthFieldLength
         0: .line 88
            aload 0 /* this */
            iload 1 /* lengthFieldLength */
            iconst_0
            iload 2 /* lengthIncludesLengthFieldLength */
            invokespecial io.netty.handler.codec.LengthFieldPrepender.<init>:(IIZ)V
         1: .line 89
            return
        end local 2 // boolean lengthIncludesLengthFieldLength
        end local 1 // int lengthFieldLength
        end local 0 // io.netty.handler.codec.LengthFieldPrepender this
      LocalVariableTable:
        Start  End  Slot                             Name  Signature
            0    2     0                             this  Lio/netty/handler/codec/LengthFieldPrepender;
            0    2     1                lengthFieldLength  I
            0    2     2  lengthIncludesLengthFieldLength  Z
    MethodParameters:
                                 Name  Flags
      lengthFieldLength                
      lengthIncludesLengthFieldLength  

  public void <init>(int, int);
    descriptor: (II)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=3, args_size=3
        start local 0 // io.netty.handler.codec.LengthFieldPrepender this
        start local 1 // int lengthFieldLength
        start local 2 // int lengthAdjustment
         0: .line 103
            aload 0 /* this */
            iload 1 /* lengthFieldLength */
            iload 2 /* lengthAdjustment */
            iconst_0
            invokespecial io.netty.handler.codec.LengthFieldPrepender.<init>:(IIZ)V
         1: .line 104
            return
        end local 2 // int lengthAdjustment
        end local 1 // int lengthFieldLength
        end local 0 // io.netty.handler.codec.LengthFieldPrepender this
      LocalVariableTable:
        Start  End  Slot               Name  Signature
            0    2     0               this  Lio/netty/handler/codec/LengthFieldPrepender;
            0    2     1  lengthFieldLength  I
            0    2     2   lengthAdjustment  I
    MethodParameters:
                   Name  Flags
      lengthFieldLength  
      lengthAdjustment   

  public void <init>(int, int, boolean);
    descriptor: (IIZ)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=4, args_size=4
        start local 0 // io.netty.handler.codec.LengthFieldPrepender this
        start local 1 // int lengthFieldLength
        start local 2 // int lengthAdjustment
        start local 3 // boolean lengthIncludesLengthFieldLength
         0: .line 122
            aload 0 /* this */
            getstatic java.nio.ByteOrder.BIG_ENDIAN:Ljava/nio/ByteOrder;
            iload 1 /* lengthFieldLength */
            iload 2 /* lengthAdjustment */
            iload 3 /* lengthIncludesLengthFieldLength */
            invokespecial io.netty.handler.codec.LengthFieldPrepender.<init>:(Ljava/nio/ByteOrder;IIZ)V
         1: .line 123
            return
        end local 3 // boolean lengthIncludesLengthFieldLength
        end local 2 // int lengthAdjustment
        end local 1 // int lengthFieldLength
        end local 0 // io.netty.handler.codec.LengthFieldPrepender this
      LocalVariableTable:
        Start  End  Slot                             Name  Signature
            0    2     0                             this  Lio/netty/handler/codec/LengthFieldPrepender;
            0    2     1                lengthFieldLength  I
            0    2     2                 lengthAdjustment  I
            0    2     3  lengthIncludesLengthFieldLength  Z
    MethodParameters:
                                 Name  Flags
      lengthFieldLength                
      lengthAdjustment                 
      lengthIncludesLengthFieldLength  

  public void <init>(java.nio.ByteOrder, int, int, boolean);
    descriptor: (Ljava/nio/ByteOrder;IIZ)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=5, args_size=5
        start local 0 // io.netty.handler.codec.LengthFieldPrepender this
        start local 1 // java.nio.ByteOrder byteOrder
        start local 2 // int lengthFieldLength
        start local 3 // int lengthAdjustment
        start local 4 // boolean lengthIncludesLengthFieldLength
         0: .line 141
            aload 0 /* this */
            invokespecial io.netty.handler.codec.MessageToMessageEncoder.<init>:()V
         1: .line 144
            iload 2 /* lengthFieldLength */
            iconst_1
            if_icmpeq 9
            iload 2 /* lengthFieldLength */
            iconst_2
            if_icmpeq 9
         2: .line 145
            iload 2 /* lengthFieldLength */
            iconst_3
            if_icmpeq 9
            iload 2 /* lengthFieldLength */
            iconst_4
            if_icmpeq 9
         3: .line 146
            iload 2 /* lengthFieldLength */
            bipush 8
            if_icmpeq 9
         4: .line 147
            new java.lang.IllegalArgumentException
            dup
         5: .line 148
            new java.lang.StringBuilder
            dup
            ldc "lengthFieldLength must be either 1, 2, 3, 4, or 8: "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
         6: .line 149
            iload 2 /* lengthFieldLength */
            invokevirtual java.lang.StringBuilder.append:(I)Ljava/lang/StringBuilder;
         7: .line 148
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
         8: .line 147
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
         9: .line 151
      StackMap locals: io.netty.handler.codec.LengthFieldPrepender java.nio.ByteOrder int int int
      StackMap stack:
            aload 1 /* byteOrder */
            ldc "byteOrder"
            invokestatic io.netty.util.internal.ObjectUtil.checkNotNull:(Ljava/lang/Object;Ljava/lang/String;)Ljava/lang/Object;
            pop
        10: .line 153
            aload 0 /* this */
            aload 1 /* byteOrder */
            putfield io.netty.handler.codec.LengthFieldPrepender.byteOrder:Ljava/nio/ByteOrder;
        11: .line 154
            aload 0 /* this */
            iload 2 /* lengthFieldLength */
            putfield io.netty.handler.codec.LengthFieldPrepender.lengthFieldLength:I
        12: .line 155
            aload 0 /* this */
            iload 4 /* lengthIncludesLengthFieldLength */
            putfield io.netty.handler.codec.LengthFieldPrepender.lengthIncludesLengthFieldLength:Z
        13: .line 156
            aload 0 /* this */
            iload 3 /* lengthAdjustment */
            putfield io.netty.handler.codec.LengthFieldPrepender.lengthAdjustment:I
        14: .line 157
            return
        end local 4 // boolean lengthIncludesLengthFieldLength
        end local 3 // int lengthAdjustment
        end local 2 // int lengthFieldLength
        end local 1 // java.nio.ByteOrder byteOrder
        end local 0 // io.netty.handler.codec.LengthFieldPrepender this
      LocalVariableTable:
        Start  End  Slot                             Name  Signature
            0   15     0                             this  Lio/netty/handler/codec/LengthFieldPrepender;
            0   15     1                        byteOrder  Ljava/nio/ByteOrder;
            0   15     2                lengthFieldLength  I
            0   15     3                 lengthAdjustment  I
            0   15     4  lengthIncludesLengthFieldLength  Z
    MethodParameters:
                                 Name  Flags
      byteOrder                        
      lengthFieldLength                
      lengthAdjustment                 
      lengthIncludesLengthFieldLength  

  protected void encode(io.netty.channel.ChannelHandlerContext, io.netty.buffer.ByteBuf, java.util.List<java.lang.Object>);
    descriptor: (Lio/netty/channel/ChannelHandlerContext;Lio/netty/buffer/ByteBuf;Ljava/util/List;)V
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=5, locals=5, args_size=4
        start local 0 // io.netty.handler.codec.LengthFieldPrepender this
        start local 1 // io.netty.channel.ChannelHandlerContext ctx
        start local 2 // io.netty.buffer.ByteBuf msg
        start local 3 // java.util.List out
         0: .line 161
            aload 2 /* msg */
            invokevirtual io.netty.buffer.ByteBuf.readableBytes:()I
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.lengthAdjustment:I
            iadd
            istore 4 /* length */
        start local 4 // int length
         1: .line 162
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.lengthIncludesLengthFieldLength:Z
            ifeq 3
         2: .line 163
            iload 4 /* length */
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.lengthFieldLength:I
            iadd
            istore 4 /* length */
         3: .line 166
      StackMap locals: int
      StackMap stack:
            iload 4 /* length */
            ifge 7
         4: .line 167
            new java.lang.IllegalArgumentException
            dup
         5: .line 168
            new java.lang.StringBuilder
            dup
            ldc "Adjusted frame length ("
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 4 /* length */
            invokevirtual java.lang.StringBuilder.append:(I)Ljava/lang/StringBuilder;
            ldc ") is less than zero"
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
         6: .line 167
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
         7: .line 171
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.lengthFieldLength:I
            tableswitch { // 1 - 8
                    1: 8
                    2: 14
                    3: 20
                    4: 26
                    5: 30
                    6: 30
                    7: 30
                    8: 28
              default: 30
          }
         8: .line 173
      StackMap locals:
      StackMap stack:
            iload 4 /* length */
            sipush 256
            if_icmplt 12
         9: .line 174
            new java.lang.IllegalArgumentException
            dup
        10: .line 175
            new java.lang.StringBuilder
            dup
            ldc "length does not fit into a byte: "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 4 /* length */
            invokevirtual java.lang.StringBuilder.append:(I)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
        11: .line 174
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
        12: .line 177
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 1 /* ctx */
            invokeinterface io.netty.channel.ChannelHandlerContext.alloc:()Lio/netty/buffer/ByteBufAllocator;
            iconst_1
            invokeinterface io.netty.buffer.ByteBufAllocator.buffer:(I)Lio/netty/buffer/ByteBuf;
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.byteOrder:Ljava/nio/ByteOrder;
            invokevirtual io.netty.buffer.ByteBuf.order:(Ljava/nio/ByteOrder;)Lio/netty/buffer/ByteBuf;
            iload 4 /* length */
            i2b
            invokevirtual io.netty.buffer.ByteBuf.writeByte:(I)Lio/netty/buffer/ByteBuf;
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        13: .line 178
            goto 31
        14: .line 180
      StackMap locals:
      StackMap stack:
            iload 4 /* length */
            ldc 65536
            if_icmplt 18
        15: .line 181
            new java.lang.IllegalArgumentException
            dup
        16: .line 182
            new java.lang.StringBuilder
            dup
            ldc "length does not fit into a short integer: "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 4 /* length */
            invokevirtual java.lang.StringBuilder.append:(I)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
        17: .line 181
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
        18: .line 184
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 1 /* ctx */
            invokeinterface io.netty.channel.ChannelHandlerContext.alloc:()Lio/netty/buffer/ByteBufAllocator;
            iconst_2
            invokeinterface io.netty.buffer.ByteBufAllocator.buffer:(I)Lio/netty/buffer/ByteBuf;
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.byteOrder:Ljava/nio/ByteOrder;
            invokevirtual io.netty.buffer.ByteBuf.order:(Ljava/nio/ByteOrder;)Lio/netty/buffer/ByteBuf;
            iload 4 /* length */
            i2s
            invokevirtual io.netty.buffer.ByteBuf.writeShort:(I)Lio/netty/buffer/ByteBuf;
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        19: .line 185
            goto 31
        20: .line 187
      StackMap locals:
      StackMap stack:
            iload 4 /* length */
            ldc 16777216
            if_icmplt 24
        21: .line 188
            new java.lang.IllegalArgumentException
            dup
        22: .line 189
            new java.lang.StringBuilder
            dup
            ldc "length does not fit into a medium integer: "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 4 /* length */
            invokevirtual java.lang.StringBuilder.append:(I)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
        23: .line 188
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
        24: .line 191
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 1 /* ctx */
            invokeinterface io.netty.channel.ChannelHandlerContext.alloc:()Lio/netty/buffer/ByteBufAllocator;
            iconst_3
            invokeinterface io.netty.buffer.ByteBufAllocator.buffer:(I)Lio/netty/buffer/ByteBuf;
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.byteOrder:Ljava/nio/ByteOrder;
            invokevirtual io.netty.buffer.ByteBuf.order:(Ljava/nio/ByteOrder;)Lio/netty/buffer/ByteBuf;
            iload 4 /* length */
            invokevirtual io.netty.buffer.ByteBuf.writeMedium:(I)Lio/netty/buffer/ByteBuf;
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        25: .line 192
            goto 31
        26: .line 194
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 1 /* ctx */
            invokeinterface io.netty.channel.ChannelHandlerContext.alloc:()Lio/netty/buffer/ByteBufAllocator;
            iconst_4
            invokeinterface io.netty.buffer.ByteBufAllocator.buffer:(I)Lio/netty/buffer/ByteBuf;
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.byteOrder:Ljava/nio/ByteOrder;
            invokevirtual io.netty.buffer.ByteBuf.order:(Ljava/nio/ByteOrder;)Lio/netty/buffer/ByteBuf;
            iload 4 /* length */
            invokevirtual io.netty.buffer.ByteBuf.writeInt:(I)Lio/netty/buffer/ByteBuf;
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        27: .line 195
            goto 31
        28: .line 197
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 1 /* ctx */
            invokeinterface io.netty.channel.ChannelHandlerContext.alloc:()Lio/netty/buffer/ByteBufAllocator;
            bipush 8
            invokeinterface io.netty.buffer.ByteBufAllocator.buffer:(I)Lio/netty/buffer/ByteBuf;
            aload 0 /* this */
            getfield io.netty.handler.codec.LengthFieldPrepender.byteOrder:Ljava/nio/ByteOrder;
            invokevirtual io.netty.buffer.ByteBuf.order:(Ljava/nio/ByteOrder;)Lio/netty/buffer/ByteBuf;
            iload 4 /* length */
            i2l
            invokevirtual io.netty.buffer.ByteBuf.writeLong:(J)Lio/netty/buffer/ByteBuf;
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        29: .line 198
            goto 31
        30: .line 200
      StackMap locals:
      StackMap stack:
            new java.lang.Error
            dup
            ldc "should not reach here"
            invokespecial java.lang.Error.<init>:(Ljava/lang/String;)V
            athrow
        31: .line 202
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 2 /* msg */
            invokevirtual io.netty.buffer.ByteBuf.retain:()Lio/netty/buffer/ByteBuf;
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        32: .line 203
            return
        end local 4 // int length
        end local 3 // java.util.List out
        end local 2 // io.netty.buffer.ByteBuf msg
        end local 1 // io.netty.channel.ChannelHandlerContext ctx
        end local 0 // io.netty.handler.codec.LengthFieldPrepender this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0   33     0    this  Lio/netty/handler/codec/LengthFieldPrepender;
            0   33     1     ctx  Lio/netty/channel/ChannelHandlerContext;
            0   33     2     msg  Lio/netty/buffer/ByteBuf;
            0   33     3     out  Ljava/util/List<Ljava/lang/Object;>;
            1   33     4  length  I
    Exceptions:
      throws java.lang.Exception
    Signature: (Lio/netty/channel/ChannelHandlerContext;Lio/netty/buffer/ByteBuf;Ljava/util/List<Ljava/lang/Object;>;)V
    MethodParameters:
      Name  Flags
      ctx   
      msg   
      out   

  protected void encode(io.netty.channel.ChannelHandlerContext, java.lang.Object, java.util.List);
    descriptor: (Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;Ljava/util/List;)V
    flags: (0x1044) ACC_PROTECTED, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=4, locals=4, args_size=4
         0: .line 1
            aload 0
            aload 1
            aload 2
            checkcast io.netty.buffer.ByteBuf
            aload 3
            invokevirtual io.netty.handler.codec.LengthFieldPrepender.encode:(Lio/netty/channel/ChannelHandlerContext;Lio/netty/buffer/ByteBuf;Ljava/util/List;)V
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature
    Exceptions:
      throws java.lang.Exception
}
Signature: Lio/netty/handler/codec/MessageToMessageEncoder<Lio/netty/buffer/ByteBuf;>;
SourceFile: "LengthFieldPrepender.java"
InnerClasses:
  public abstract Sharable = io.netty.channel.ChannelHandler$Sharable of io.netty.channel.ChannelHandler
    RuntimeVisibleAnnotations: 
      io.netty.channel.ChannelHandler$Sharable()