A simple Java implementation of the core Bitcoin classes to handle generation of Bitcoin transactions.
The existing Bitcoinj project is a complete implementation of the Bitcoin protocol. This makes it overkill for the most common Bitcoin operation: generation of transactions.
This project is focused on allowing developers to generate Bitcoin transactions with a minimal learning curve.
The most common use case is a standard Bitcoin transaction, where ownership of some amount of bitcoins is transferred from one owner to another:
final SimpleSpendTransactionBuilder builder = new SimpleSpendTransactionBuilder();
builder.sendFromTransaction(existingTransactionId);
builder.sendToRecipient(Value.fromString("0.1BTC"), new Address("12rsrcBjfx3wKxb4VNK5Ajt1JMVVYz3SYr"));
builder.sendToRecipient(Value.fromString("5mBTC"), new Address("15hKjJscmhquUvoHT997Mehq6sYpvjNHNb"));
builder.useKeys(...);
final Transaction trans = builder.build();
Once the transaction is built there are a number of options as to what to do with it, but the most common is to obtain a dump of it which can then be broadcast by any compliant bitcoin implementation:
final Generator<Transaction> gen = new TransactionGeneratorRawImpl();
gen.startGen();
gen.generate(trans);
final String raw = Utils.bytesToHexString(gen.finishGen());
Note that because this code does not access to the blockchain directly it is not able to verify information provided. Specifically, it cannot confirm anything about the transactions from which funds are coming, up to and including their very existance, nor can it confirm that all expenditure is accounted for. As such, users need to be careful when creating transactions that they do not
Also, the design of this code is to provide safety over speed. For example, ImmutableList<Byte> is preferred over byte[]. This results in code which is significantly slower to run, however gives less oppportunities for shooting yourself in the foot. Given that this is dealing with items of real value this is considered an acceptable trade-off, however if you want to use this as the basis for a high-volume system you might want to do some benchmarking first.
License
Copyright 2012 Weald Technology Trading Limited.
Licensed 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.