用java簡單分析下比特幣區塊鏈

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.LinkedList;
import java.util.List;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
 
import org.bitcoinj.core.Block;
import org.bitcoinj.core.Context;
import org.bitcoinj.core.NetworkParameters;
import org.bitcoinj.core.Transaction;
import org.bitcoinj.params.MainNetParams;
import org.bitcoinj.utils.BlockFileLoader;
 
 
public class SimpleDailyTxCount {
 
// Location of block files. This is where your blocks are located.
// Check the documentation of Bitcoin Core if you are using
// it, or use any other directory with blk*dat files. 
static String PREFIX = "/path/to/your/bitcoin/blocks/";
 
// A simple method with everything in it
public void doSomething() {
 
// Just some initial setup
NetworkParameters np = new MainNetParams();
Context.getOrCreate(MainNetParams.get());
 
// We create a BlockFileLoader object by passing a list of files.
// The list of files is built with the method buildList(), see
// below for its definition.
BlockFileLoader loader = new BlockFileLoader(np,buildList());
 
// We are going to store the results in a map of the form 
// day -> n. of transactions
Map<String, Integer> dailyTotTxs = new HashMap<>();
 
// A simple counter to have an idea of the progress
int blockCounter = 0;
 
// bitcoinj does all the magic: from the list of files in the loader
// it builds a list of blocks. We iterate over it using the following
// for loop
for (Block block : loader) {
 
blockCounter++;
// This gives you an idea of the progress
System.out.println("Analysing block "+blockCounter);
 
// Extract the day from the block: we are only interested 
// in the day, not in the time. Block.getTime() returns 
// a Date, which is here converted to a string.
String day = new SimpleDateFormat("yyyy-MM-dd").format(block.getTime());
 
// Now we start populating the map day -> number of transactions.
// Is this the first time we see the date? If yes, create an entry
if (!dailyTotTxs.containsKey(day)) {
dailyTotTxs.put(day, 0);
}
 
// The following is highly inefficient: we could simply do
// block.getTransactions().size(), but is shows you
// how to iterate over transactions in a block
// So, we simply iterate over all transactions in the
// block and for each of them we add 1 to the corresponding
// entry in the map
for ( Transaction tx: block.getTransactions() ) {
dailyTotTxs.put(day,dailyTotTxs.get(day)+1);
}
} // End of iteration over blocks
 
// Finally, let's print the results
for ( String d: dailyTotTxs.keySet()) {
System.out.println(d+","+dailyTotTxs.get(d));
}
}// end of doSomething() method.
 
 
// The method returns a list of files in a directory according to a certain
// pattern (block files have name blkNNNNN.dat)
private List<File> buildList() {
List<File> list = new LinkedList<File>();
for (int i = 0; true; i++) {
File file = new File(PREFIX + String.format(Locale.US, "blk%05d.dat", i));
if (!file.exists())
break;
list.add(file);
}
return list;
}
 
 
// Main method: simply invoke everything
public static void main(String[] args) {
SimpleDailyTxCount tb = new SimpleDailyTxCount();
tb.doSomething();
}
 
}