java怎么digest认证调用海康威视/ISAPI/Streaming/channels/1/picture的接口

在Java中进行摘要认证（Digest Authentication），可以使用Java的HttpURLConnection类来发送HTTP请求。以下是一个使用HttpURLConnection发送带有Digest认证的GET请求的示例代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class DigestAuthExample {

    public static void main(String[] args) throws Exception {
        String url = "http://IP地址/ISAPI/Streaming/channels/1/picture";
        String username = "admin";
        String password = "12345";

        HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
        connection.setRequestMethod("GET");

        // 添加Digest认证头部
        String authHeader = getDigestAuthHeader(connection, username, password);
        connection.setRequestProperty("Authorization", authHeader);

        // 发送请求
        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);

        // 读取响应内容
        BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        System.out.println("Response Content: " + response.toString());
    }

    private static String getDigestAuthHeader(HttpURLConnection connection, String username, String password) throws IOException {
        String realm = null;
        String nonce = null;
        String qop = null;
        String cnonce = null;
        String nc = null;

        // 发送第一次请求，获取服务器返回的Digest认证参数
        int responseCode = connection.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_UNAUTHORIZED) {
            String authHeader = connection.getHeaderField("WWW-Authenticate");
            String[] authParams = authHeader.split(",\\s*");

            // 解析Digest认证参数
            for (String authParam : authParams) {
                String[] keyValue = authParam.split("=", 2);
                String key = keyValue[0].trim();
                String value = keyValue[1].trim().replaceAll("\"", "");
                if (key.equalsIgnoreCase("realm")) {
                    realm = value;
                } else if (key.equalsIgnoreCase("nonce")) {
                    nonce = value;
                } else if (key.equalsIgnoreCase("qop")) {
                    qop = value;
                }
            }

            // 计算响应摘要
            String ha1 = DigestUtils.md5Hex(username + ":" + realm + ":" + password);
            String ha2 = DigestUtils.md5Hex("GET" + ":" + "/ISAPI/Streaming/channels/1/picture");
            nc = "00000001";
            cnonce = DigestUtils.md5Hex(String.valueOf(System.nanoTime()));
            String response = DigestUtils.md5Hex(ha1 + ":" + nonce + ":" + nc + ":" + cnonce + ":" + qop + ":" + ha2);

            // 构造Digest认证头部
            StringBuilder authBuilder = new StringBuilder("Digest ");
            authBuilder.append("username=\"" + username + "\", ");
            authBuilder.append("realm=\"" + realm + "\", ");
            authBuilder.append("nonce=\"" + nonce + "\", ");
            authBuilder.append("uri=\"" + "/ISAPI/Streaming/channels/1/picture" + "\", ");
            authBuilder.append("qop=" + qop + ", ");
            authBuilder.append("nc=" + nc + ", ");
            authBuilder.append("cnonce=\"" + cnonce + "\", ");
            authBuilder.append("response=\"" + response + "\"");
            return authBuilder.toString();
        }
        return null;
    }
}

注意，以上代码中使用了Apache Commons Codec库的`DigestUtils.md5Hex()`方法进行MD5摘要计算，需要先导入该库。建议使用最新版本的库。

另外，由于海康威视的视频监控设备的接口通常需要使用HTTP Basic或Digest认证才能访问，因此在进行接口调用时需要先获取到正确的认证参数，并在HTTP头部添加相应的认证信息。具体的认证方式和参数可以参考海康威视设备的开发文档。