java 调用bt下载

Java调用BT下载

介绍

BT（BitTorrent）是一种常用的文件传输协议，它通过将大文件分割成小块并使用种子文件来进行下载。在Java中，我们可以通过各种开源库来实现BT下载功能。本文将介绍如何使用Java调用BT下载，并提供代码示例和详细说明。

准备工作

在开始之前，我们需要准备以下工作：

1. 安装Java Development Kit（JDK）：确保您已安装JDK，并将其配置为环境变量。
2. 引入BT下载库：我们将使用开源库bt-library来实现BT下载功能。您可以在项目的构建工具（如Maven或Gradle）中添加以下依赖项：

<dependencies>
    <dependency>
        <groupId>com.github.bsmali4</groupId>
        <artifactId>bt-library</artifactId>
        <version>1.0.2</version>
    </dependency>
</dependencies>

BT下载实现步骤

下面是使用Java实现BT下载的基本步骤：

1. 解析种子文件：使用TorrentParser类解析种子文件，并获取下载文件的相关信息。

import bt.bencoding.BEParser;
import bt.bencoding.model.BElement;
import bt.bencoding.model.BList;
import bt.bencoding.model.BMap;
import bt.bencoding.model.BString;

import java.io.FileInputStream;
import java.io.InputStream;

public class TorrentParser {

    public static void main(String[] args) throws Exception {
        String torrentFile = "example.torrent";
        InputStream inputStream = new FileInputStream(torrentFile);
        BElement element = new BEParser(inputStream).parse();
        BMap map = (BMap) element;

        BList announceList = (BList) map.get(new BString("announce-list"));
        BString announce = (BString) announceList.get(0);

        BList info = (BList) map.get(new BString("info"));
        BString name = (BString) info.get(0);
        BString length = (BString) info.get(1);

        System.out.println("Torrent Name: " + name.getString());
        System.out.println("Torrent Length: " + length.getString());
        System.out.println("Torrent Announce: " + announce.getString());
    }
}

2. 创建下载任务：使用TorrentProcessor类创建BT下载任务，并配置下载目录、种子文件和监听端口。

import bt.data.Storage;

import java.io.File;

public class TorrentProcessor {

    public static void main(String[] args) throws Exception {
        String downloadDir = "/path/to/download/dir";
        String torrentFile = "example.torrent";
        int listenPort = 6881;

        File storageDir = new File(downloadDir);
        Storage storage = Storage.builder().destination(storageDir).build();

        Torrent torrent = Torrent.load(new FileInputStream(torrentFile), storage);
        TorrentSession torrentSession = TorrentSession.newInstance(torrent, storage);
        PeerIdGenerator peerIdGenerator = new PeerIdGenerator();

        torrentSession.setPeerId(peerIdGenerator.generatePeerId());
        torrentSession.setListenPort(listenPort);

        torrentSession.start();
    }
}

3. 监听下载进度：使用TorrentSession类监听并处理下载进度、完成事件。

import bt.data.Bitfield;
import bt.data.Block;
import bt.data.Chunk;
import bt.metainfo.Torrent;
import bt.runtime.BtClient;
import bt.runtime.Config;
import bt.runtime.PieceStatistics;
import bt.runtime.TorrentSessionState;
import bt.runtime.eval.EvaluatorBuilder;
import bt.service.IRuntimeLifecycleBinder;
import bt.service.IRuntimeLifecycleBinder.RuntimeLifecycle;
import bt.service.ServiceException;

import java.util.BitSet;

public class TorrentSession implements IRuntimeLifecycleBinder {

    private final BtClient client;
    private final TorrentSessionState state;

    private TorrentSession(BtClient client, TorrentSessionState state) {
        this.client = client;
        this.state = state;
    }

    public static TorrentSession newInstance(Torrent torrent, Storage storage) {
        Config config = new Config();
        EvaluatorBuilder evaluatorBuilder = new EvaluatorBuilder();
        BtClient client = new BtClient(
                torrent,
                storage,
                evaluatorBuilder,
                config
        );
        TorrentSessionState state = new TorrentSessionState();

        return new TorrentSession(client, state);
    }

    public void start() throws ServiceException {
        this.client.start(this);
    }

    public void pause() throws ServiceException {
        this.client.pause(this);
    }

    @RuntimeLifecycle
    public void onPieceCompleted(PieceStatistics pieceStatistics) {
        int pieceIndex = pieceStatistics.getPieceIndex();
        BitSet availablePieces = pieceStatistics.getAvailablePieces();
        Bitfield bitfield = pieceStatistics.getBitfield();
        System.out.println("Piece " + pieceIndex + " completed!");
    }

    @RuntimeLifecycle
    public void on