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FetchBlock example: Enhance this example to be able to connect DNS discovered peers so that you don't need to install bitcoind locally.

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Bo-Ye 2017-07-08 21:14:09 +12:00 committed by Andreas Schildbach
parent a2bb46bcd1
commit 3e62906971
1 changed files with 42 additions and 5 deletions
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45
examples/src/main/java/org/bitcoinj/examples/FetchBlock.java
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@ -17,34 +17,71 @@
package org.bitcoinj.examples; package org.bitcoinj.examples;
import joptsimple.OptionException;
import joptsimple.OptionParser;
import joptsimple.OptionSet;
import org.bitcoinj.core.*; import org.bitcoinj.core.*;
import org.bitcoinj.net.discovery.DnsDiscovery;
import org.bitcoinj.params.TestNet3Params; import org.bitcoinj.params.TestNet3Params;
import org.bitcoinj.store.BlockStore; import org.bitcoinj.store.BlockStore;
import org.bitcoinj.store.MemoryBlockStore; import org.bitcoinj.store.MemoryBlockStore;
import org.bitcoinj.utils.BriefLogFormatter; import org.bitcoinj.utils.BriefLogFormatter;
import java.net.InetAddress; import java.net.InetAddress;
import java.util.List;
import java.util.concurrent.Future; import java.util.concurrent.Future;
/** /**
* Downloads the block given a block hash from the localhost node and prints it out. * <p>Downloads the block given a block hash from the remote or localhost node and prints it out.</p>
* <p>When downloading from localhost, run bitcoind locally: bitcoind -testnet -daemon.
* After bitcoind is up and running, use command: org.bitcoinj.examples.FetchBlock --localhost &lt;blockHash&gt; </p>
* <p>Otherwise, use command: org.bitcoinj.examples.FetchBlock &lt;blockHash&gt;, this command will download blocks from a peer generated by DNS seeds.</p>
*/ */
public class FetchBlock { public class FetchBlock {
public static void main(String[] args) throws Exception { public static void main(String[] args) throws Exception {
BriefLogFormatter.init(); BriefLogFormatter.init();
// Parse command line arguments
OptionParser parser = new OptionParser();
OptionSet opts = null;
List<String> nonOpts = null;
try {
parser.accepts("localhost", "Connect to the localhost node");
parser.accepts("help", "Displays program options");
opts = parser.parse(args);
if (opts.has("help")) {
System.out.println("usage: org.bitcoinj.examples.FetchBlock [--localhost] <blockHash>");
parser.printHelpOn(System.out);
return;
}
nonOpts = opts.nonOptionArguments();
if (nonOpts.size() != 1) {
throw new IllegalArgumentException("Incorrect number of block hash, please provide only one block hash.");
}
} catch (OptionException | IllegalArgumentException e) {
System.err.println(e.getMessage());
System.err.println("usage: org.bitcoinj.examples.FetchBlock [--localhost] <blockHash>");
parser.printHelpOn(System.err);
return;
}
// Connect to testnet and find a peer
System.out.println("Connecting to node"); System.out.println("Connecting to node");
final NetworkParameters params = TestNet3Params.get(); final NetworkParameters params = TestNet3Params.get();
BlockStore blockStore = new MemoryBlockStore(params); BlockStore blockStore = new MemoryBlockStore(params);
BlockChain chain = new BlockChain(params, blockStore); BlockChain chain = new BlockChain(params, blockStore);
PeerGroup peerGroup = new PeerGroup(params, chain); PeerGroup peerGroup = new PeerGroup(params, chain);
peerGroup.start(); if (!opts.has("localhost")) {
peerGroup.addPeerDiscovery(new DnsDiscovery(params));
} else {
PeerAddress addr = new PeerAddress(params, InetAddress.getLocalHost()); PeerAddress addr = new PeerAddress(params, InetAddress.getLocalHost());
peerGroup.addAddress(addr); peerGroup.addAddress(addr);
}
peerGroup.start();
peerGroup.waitForPeers(1).get(); peerGroup.waitForPeers(1).get();
Peer peer = peerGroup.getConnectedPeers().get(0); Peer peer = peerGroup.getConnectedPeers().get(0);
Sha256Hash blockHash = Sha256Hash.wrap(args[0]); // Retrieve a block through a peer
Sha256Hash blockHash = Sha256Hash.wrap(nonOpts.get(0));
Future<Block> future = peer.getBlock(blockHash); Future<Block> future = peer.getBlock(blockHash);
System.out.println("Waiting for node to send us the requested block: " + blockHash); System.out.println("Waiting for node to send us the requested block: " + blockHash);
Block block = future.get(); Block block = future.get();