netty5/example/src/main/java/io/netty/example/factorial/BigIntegerDecoder.java
Trustin Lee 223efc5f99 Clean up the examples
Motivation:

The examples have not been updated since long time ago, showing various
issues fixed in this commit.

Modifications:

- Overall simplification to reduce LoC
  - Use system properties to get options instead of parsing args.
  - Minimize option validation
  - Just use System.out/err instead of Logger
  - Do not pass config as parameters - just access it directly
  - Move the main logic to main(String[]) instead of creating a new
    instance meaninglessly
    - Update netty-build-21 to make checkstyle not complain
  - Remove 'throws Exception' clause if possible
- Line wrap at 120 (previously at 80)
- Add an option to enable SSL for most examples
- Use ChannelFuture.sync() instead of await()
- Use System.out for the actual result. Use System.err otherwise.
- Delete examples that are not very useful:
  - applet
  - websocket/html5
  - websocketx/sslserver
  - localecho/multithreaded
- Add run-example.sh which simplifies launching an example from command
  line
- Rewrite FileServer example

Result:

Shorter and simpler examples.  A user can focus more on what it actually
does than miscellaneous stuff.  A user can launch an example very
easily.
2014-05-23 17:13:09 +09:00

64 lines
2.1 KiB
Java

/*
* Copyright 2012 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.example.factorial;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.CorruptedFrameException;
import java.math.BigInteger;
import java.util.List;
/**
* Decodes the binary representation of a {@link BigInteger} prepended
* with a magic number ('F' or 0x46) and a 32-bit integer length prefix into a
* {@link BigInteger} instance. For example, { 'F', 0, 0, 0, 1, 42 } will be
* decoded into new BigInteger("42").
*/
public class BigIntegerDecoder extends ByteToMessageDecoder {
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
// Wait until the length prefix is available.
if (in.readableBytes() < 5) {
return;
}
in.markReaderIndex();
// Check the magic number.
int magicNumber = in.readUnsignedByte();
if (magicNumber != 'F') {
in.resetReaderIndex();
throw new CorruptedFrameException("Invalid magic number: " + magicNumber);
}
// Wait until the whole data is available.
int dataLength = in.readInt();
if (in.readableBytes() < dataLength) {
in.resetReaderIndex();
return;
}
// Convert the received data into a new BigInteger.
byte[] decoded = new byte[dataLength];
in.readBytes(decoded);
out.add(new BigInteger(decoded));
}
}