Java通过magnet 连接下载torrent 文件代码示例

Java通过magnet连接下载torrent文件需要用到第三方库，比如BT种子下载器Transmission的Java API。

以下是一个简单的示例代码：

import java.net.URL;
import java.util.concurrent.TimeUnit;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.util.EntityUtils;
import org.json.JSONObject;
import org.json.JSONTokener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import com.github.axet.wget.WGet;
import com.github.axet.wget.info.URLInfo;
import com.github.axet.wget.info.ex.DownloadError;
import com.github.axet.wget.info.ex.DownloadInterruptedError;
import com.github.axet.wget.info.ex.DownloadMultipartError;
import com.github.axet.wget.info.ex.DownloadRetry;
import com.github.axet.wget.info.ex.DownloadSSLException;
import com.github.axet.wget.info.ex.DownloadTimeoutException;
import com.github.axet.wget.info.ex.DownloadVerificationException;

@RestController
public class TorrentDownloadController {

    private static final Logger LOGGER = LoggerFactory.getLogger(TorrentDownloadController.class);

    private static final String TRANSMISSION_API_VERSION = "v2.94";
    private static final String TRANSMISSION_RPC_URI = "/transmission/rpc";
    private static final String TRANSMISSION_RPC_URL = "http://localhost:9091" + TRANSMISSION_RPC_URI;

    private static final String MAGNET_URI_PREFIX = "magnet:?xt=urn:btih:";

    private static final int CONNECT_TIMEOUT = 10000;
    private static final int SOCKET_TIMEOUT = 30000;

    private static final PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();

    static {
        connectionManager.setMaxTotal(100);
        connectionManager.setDefaultMaxPerRoute(20);
    }

    @GetMapping(value = "/download/{magnetUri}", produces = MediaType.APPLICATION_JSON_VALUE)
    public JSONObject download(@PathVariable String magnetUri) throws Exception {
        LOGGER.info("Downloading torrent from magnet URI: {}", magnetUri);

        String torrentUrl = getTorrentUrlFromMagnetUri(magnetUri);
        LOGGER.info("Torrent URL: {}", torrentUrl);

        // Download torrent file
        String torrentFilePath = downloadTorrentFile(torrentUrl);
        LOGGER.info("Torrent file downloaded to: {}", torrentFilePath);

        // Add torrent to Transmission
        JSONObject addTorrentResponse = addTorrentToTransmission(torrentFilePath);
        LOGGER.info("Add torrent response: {}", addTorrentResponse);

        return addTorrentResponse;
    }

    private String getTorrentUrlFromMagnetUri(String magnetUri) throws Exception {
        if (!magnetUri.startsWith(MAGNET_URI_PREFIX)) {
            throw new IllegalArgumentException("Invalid magnet URI: " + magnetUri);
        }

        String hash = magnetUri.substring(MAGNET_URI_PREFIX.length());
        String infoHash = hash.split("&")[0];

        String infoUrl = "https://itorrents.org/torrent/" + infoHash + ".torrent";

        HttpClient httpClient = HttpClientBuilder.create()
                .setConnectionManager(connectionManager)
                .setConnectionManagerShared(true)
                .build();

        HttpGet httpGet = new HttpGet(infoUrl);
        httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36");

        HttpResponse response = httpClient.execute(httpGet);

        if (response.getStatusLine().getStatusCode() != 200) {
            throw new RuntimeException("Failed to get torrent file URL, HTTP error code: " + response.getStatusLine().getStatusCode());
        }

        String responseBody = EntityUtils.toString(response.getEntity());
        JSONObject jsonResponse = new JSONObject(new JSONTokener(responseBody));

        String torrentUrl = jsonResponse.getString("url");

        return torrentUrl;
    }

    private String downloadTorrentFile(String torrentUrl) throws Exception {
        URL url = new URL(torrentUrl);
        URLInfo urlInfo = new URLInfo(url);

        String fileName = urlInfo.getFile().substring(urlInfo.getFile().lastIndexOf('/') + 1);

        WGet wGet = new WGet(url, fileName);
        wGet.setConnectTimeout(CONNECT_TIMEOUT);
        wGet.setReadTimeout(SOCKET_TIMEOUT);

        try {
            wGet.download();
        } catch (DownloadRetry e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        } catch (DownloadTimeoutException e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        } catch (DownloadMultipartError e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        } catch (DownloadInterruptedError e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        } catch (DownloadVerificationException e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        } catch (DownloadSSLException e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        } catch (DownloadError e) {
            LOGGER.error("Failed to download torrent file: {}", e.getMessage());
            throw new RuntimeException(e);
        }

        return fileName;
    }

    private JSONObject addTorrentToTransmission(String torrentFilePath) throws Exception {
        String addTorrentUrl = TRANSMISSION_RPC_URL + "/" + TRANSMISSION_API_VERSION + "/torrent-add";

        HttpClient httpClient = HttpClientBuilder.create()
                .setConnectionManager(connectionManager)
                .setConnectionManagerShared(true)
                .build();

        HttpGet httpGet = new HttpGet(addTorrentUrl);
        httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36");

        String jsonRequest = "{\"method\":\"torrent-add\",\"arguments\":{\"paused\":false,\"download-dir\":\"/downloads\",\"filename\":\"" + torrentFilePath + "\"}}";
        httpGet.setHeader("Content-Type", "application/json");
        httpGet.setHeader("X-Transmission-Session-Id", "null");
        httpGet.setEntity(IOUtils.toInputStream(jsonRequest));

        HttpResponse response = httpClient.execute(httpGet);

        if (response.getStatusLine().getStatusCode() == 409) {
            String sessionHeader = response.getFirstHeader("X-Transmission-Session-Id").getValue();

            httpGet.setHeader("X-Transmission-Session-Id", sessionHeader);
            httpGet.setEntity(IOUtils.toInputStream(jsonRequest));

            response = httpClient.execute(httpGet);
        }

        String responseBody = EntityUtils.toString(response.getEntity());
        JSONObject jsonResponse = new JSONObject(new JSONTokener(responseBody));

        return jsonResponse;
    }

}

这个示例代码使用了Transmission的Java API来添加torrent文件到Transmission，如果你想使用其他BT下载工具或者其他BT下载库，你需要修改相应的代码。