UserAgent 的值怎么设置

在Java中，你可以使用`setRequestProperty`方法来设置`User-Agent`头部的值。以下是一个示例：

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

public class Main {
    public static void main(String[] args) {
        String url = "http://example.com";
        String userAgent = "Your User Agent";

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

            // 设置User-Agent头部信息
            connection.setRequestProperty("User-Agent", userAgent);

            int responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                StringBuilder response = new StringBuilder();

                while ((line = reader.readLine()) != null) {
                    response.append(line);
                }
                reader.close();

                System.out.println(response.toString());
            } else {
                System.out.println("HTTP request failed. Response Code: " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

在上述示例中，我们使用`connection.setRequestProperty("User-Agent", userAgent)`来设置`User-Agent`头部的值。你可以将`userAgent`变量替换为你想要设置的具体值。根据需要，你可以添加更多的请求头部信息或者进行其他的修改和扩展。