用java简单分析下比特币区块链

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();
	}
 
}