How to use java to realize simple Bitcoin function
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I. Block definition
/ * *
* Block structure
* @ author
, /
Public class Block {
/ * *
* Block index number
, /
Private int index
/ * *
* the hash value of the current block, which is uniquely identified.
, /
Private String hash
/ * *
* generate the timestamp of the block
, /
Private long timestamp
/ * *
* Collection of transactions for the current block
, /
Private List transactions
/ * *
* proof of workload, the number of times the correct hash value is calculated
, /
Private int nonce
/ * *
* hash value of the previous block
, /
Private String previousHash
Public Block () {
Super ()
}
Public Block (int index, long timestamp, List transactions, int nonce, String previousHash, String hash) {
Super ()
This.index = index
This.timestamp = timestamp
This.transactions = transactions
This.nonce = nonce
This.previousHash = previousHash
This.hash = hash
}
}
II. Definition of transaction
/ * *
* transaction
* @ author
, /
Public class Transaction {
/ * *
* unique identification of the deal
, /
Private String id
/ * *
* the wallet address of the sender of the transaction
, /
Private String sender
/ * *
* wallet address of the recipient of the transaction
, /
Private String recipient
/ * *
* transaction amount
, /
Private int amount
Public Transaction () {
Super ()
}
Public Transaction (String id, String sender, String recipient, int amount) {
Super ()
This.id = id
This.sender = sender
This.recipient = recipient
This.amount = amount
}
}
III. Mining methods
/ * *
* Mining
* @ param blockchain entire block chain
* @ param txs requires bookkeeping and transaction records
* @ param address miner's wallet address
* @ return
, /
Private static void mineBlock (List blockchain, List txs, String address) {
/ / join the transaction rewarded by the system. Mining rewards 10 bitcoins by default.
Transaction sysTx = new Transaction (CryptoUtil.UUID (), ", address, 10)
Txs.add (sysTx)
/ / get the last block in the current block chain
Block latestBlock = blockchain.get (blockchain.size ()-1)
/ / Random number
Int nonce = 1
String hash = ""
While (true) {
Hash = CryptoUtil.SHA256 (latestBlock.getHash () + JSON.toJSONString (txs) + nonce)
If (hash.startsWith ("0000000000")) {
System.out.println ("= calculation result is correct, the number of calculations is:" + nonce+ ", hash:" + hash)
Break
}
Nonce++
System.out.println ("calculation error, hash:" + hash)
}
/ / solve the problem, you can construct a new block and add it to the block chain
Block newBlock = newBlock (latestBlock.getIndex () + 1, System.currentTimeMillis (), txs, nonce, latestBlock.getHash (), hash)
Blockchain.add (newBlock)
System.out.println ("Block chain after mining:" + JSON.toJSONString (blockchain))
}
IV. Balance calculation
/ * *
* query the balance
* @ param blockchain
* @ param address
* @ return
, /
Public static int getWalletBalance (List blockchain, String address) {
Int balance = 0
For (Block block: blockchain) {
List transactions = block.getTransactions ()
For (Transaction transaction: transactions) {
If (address.equals (transaction.getRecipient () {
Balance + = transaction.getAmount ()
}
If (address.equals (transaction.getSender () {
Balance-= transaction.getAmount ()
}
}
}
Return balance
Fifth, operating examples
Public static void main (String [] args) {
/ / create an empty blockchain
List blockchain = new ArrayList ()
/ / generate the Genesis Block
Block block = new Block (1, System.currentTimeMillis (), new ArrayList (), 1, "1", "1")
/ / add the Genesis block to the block chain
Blockchain.add (block)
System.out.println (JSON.toJSONString (blockchain))
/ / sender wallet address
String sender = "sender_wallet"
/ / recipient wallet address
String recipient = "recipient_wallet"
/ / create an empty transaction collection
List txs = new ArrayList ()
/ / Mining
MineBlock (blockchain, txs, sender)
The balance of System.out.println (sender + "wallet is:" + getWalletBalance (blockchain, sender))
/ / create an empty transaction collection
List txs1 = new ArrayList ()
/ / for transactions that have occurred but have not been recorded, the sender transfers 3 bitcoins to the receiver
Transaction tx1 = new Transaction (CryptoUtil.UUID (), sender, recipient, 3)
/ / for transactions that have occurred but not accounted for, the sender transfers 1 bitcoin to the receiver
Transaction tx2 = new Transaction (CryptoUtil.UUID (), sender, recipient, 1)
Txs1.add (tx1)
Txs1.add (tx2)
/ / Mining
MineBlock (blockchain, txs1, sender)
The balance of System.out.println (sender + "wallet is:" + getWalletBalance (blockchain, sender))
The balance of System.out.println (recipient + "wallet is:" + getWalletBalance (blockchain, recipient))
}
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