修改
Change-Id: I18193ed65cb577ff03f82079a7c0a4d98ca3f236
diff --git a/src/main/java/com/pt/utils/BencodeUtils.java b/src/main/java/com/pt/utils/BencodeUtils.java
new file mode 100644
index 0000000..2d3850d
--- /dev/null
+++ b/src/main/java/com/pt/utils/BencodeUtils.java
@@ -0,0 +1,107 @@
+package com.pt.utils;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.InetAddress;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.*;
+
+public class BencodeUtils {
+
+ // 通用bencode编码接口
+ public static void encode(Object obj, OutputStream out) throws IOException {
+ if (obj instanceof String) {
+ encodeString((String) obj, out);
+ } else if (obj instanceof Number) {
+ encodeInteger(((Number) obj).longValue(), out);
+ } else if (obj instanceof byte[]) {
+ encodeBytes((byte[]) obj, out);
+ } else if (obj instanceof List) {
+ encodeList((List<?>) obj, out);
+ } else if (obj instanceof Map) {
+ encodeMap((Map<String, Object>) obj, out);
+ } else {
+ throw new IllegalArgumentException("Unsupported type: " + obj.getClass());
+ }
+ }
+
+ public static byte[] encode(Object obj) {
+ try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+ encode(obj, baos);
+ return baos.toByteArray();
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static void encodeString(String s, OutputStream out) throws IOException {
+ byte[] bytes = s.getBytes(StandardCharsets.UTF_8);
+ out.write(String.valueOf(bytes.length).getBytes(StandardCharsets.US_ASCII));
+ out.write(':');
+ out.write(bytes);
+ }
+
+ private static void encodeBytes(byte[] bytes, OutputStream out) throws IOException {
+ out.write(String.valueOf(bytes.length).getBytes(StandardCharsets.US_ASCII));
+ out.write(':');
+ out.write(bytes);
+ }
+
+ private static void encodeInteger(long value, OutputStream out) throws IOException {
+ out.write('i');
+ out.write(Long.toString(value).getBytes(StandardCharsets.US_ASCII));
+ out.write('e');
+ }
+
+ private static void encodeList(List<?> list, OutputStream out) throws IOException {
+ out.write('l');
+ for (Object item : list) {
+ encode(item, out);
+ }
+ out.write('e');
+ }
+
+ private static void encodeMap(Map<String, Object> map, OutputStream out) throws IOException {
+ out.write('d');
+ List<String> keys = new ArrayList<>(map.keySet());
+ Collections.sort(keys); // bencode字典必须按key排序
+ for (String key : keys) {
+ encodeString(key, out);
+ encode(map.get(key), out);
+ }
+ out.write('e');
+ }
+
+ // 构造单个compact peer的二进制格式 (4字节IP + 2字节端口)
+ public static byte[] buildCompactPeer(String ip, int port) {
+ try {
+ InetAddress addr = InetAddress.getByName(ip);
+ ByteBuffer buffer = ByteBuffer.allocate(6);
+ buffer.put(addr.getAddress());
+ buffer.putShort((short) port);
+ return buffer.array();
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ // 构造多个compact peer的二进制拼接
+ public static byte[] buildCompactPeers(List<String> ips, List<Integer> ports) {
+ if (ips.size() != ports.size()) throw new IllegalArgumentException("IPs and ports list size mismatch");
+ ByteArrayOutputStream out = new ByteArrayOutputStream();
+ for (int i = 0; i < ips.size(); i++) {
+ out.write(buildCompactPeer(ips.get(i), ports.get(i)), 0, 6);
+ }
+ return out.toByteArray();
+ }
+
+ // 构造tracker响应字典，至少包含interval和peers
+ public static byte[] buildTrackerResponse(int interval, byte[] peersCompact) {
+ Map<String, Object> dict = new LinkedHashMap<>();
+ dict.put("interval", interval);
+ dict.put("peers", peersCompact);
+ return encode(dict);
+ }
+}