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();	} }