func generateSHA256(path string, queries url.Values, secret string) string { keys := make([]string, len(queries)) idx := 0 for k := range queries { keys[idx] = k idx++ } sort.Slice(keys, func(i, j int) bool { return keys[i] < keys[j] }) input := path for _, key := range keys { input = input + key + queries.Get(key) } input = secret + input + secret h := hmac.New(sha256.New, []byte(secret)) if _, err := h.Write([]byte(input)); err != nil { return "" } return hex.EncodeToString(h.Sum(nil)) }

以下是将给定的代码转换为Java的版本：

import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

public class SHA256Generator {
    public static String generateSHA256(String path, Map<String, String> queries, String secret) {
        List<String> keys = new ArrayList<>(queries.keySet());
        Collections.sort(keys);

        StringBuilder inputBuilder = new StringBuilder(path);
        for (String key : keys) {
            inputBuilder.append(key).append(queries.get(key));
        }
        String input = secret + inputBuilder.toString() + secret;

        try {
            Mac hmacSHA256 = Mac.getInstance("HmacSHA256");
            SecretKeySpec secretKey = new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
            hmacSHA256.init(secretKey);
            byte[] digest = hmacSHA256.doFinal(input.getBytes(StandardCharsets.UTF_8));
            return bytesToHex(digest);
        } catch (NoSuchAlgorithmException | InvalidKeyException e) {
            e.printStackTrace();
        }

        return "";
    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder hexStringBuilder = new StringBuilder();
        for (byte b : bytes) {
            String hex = Integer.toHexString(0xff & b);
            if (hex.length() == 1) {
                hexStringBuilder.append('0');
            }
            hexStringBuilder.append(hex);
        }
        return hexStringBuilder.toString();
    }

    public static void main(String[] args) {
        // 示例用法
        String path = "/example";
        Map<String, String> queries = new TreeMap<>();
        queries.put("param1", "value1");
        queries.put("param2", "value2");
        String secret = "your_secret";
        String sha256 = generateSHA256(path, queries, secret);
        System.out.println("SHA256: " + sha256);
    }
}

请注意，Java中没有直接的排序函数，因此我们使用了`Collections.sort()`来对查询参数进行排序。此外，还需要导入`java.nio.charset.StandardCharsets`和`javax.crypto`相关的类。

您可以在`main`方法中替换路径、查询参数和密钥来测试该方法。生成的SHA256哈希值将打印到控制台上。

希望能对您有所帮助！如有其他问题，请随时提问。