java请求外部接口参数为字节流和字符串

Java请求外部接口可以使用HttpURLConnection或者HttpClient来实现。下面是使用HttpURLConnection发送请求的示例代码：

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

public class HttpUrlConnectionExample {

    public static void main(String[] args) throws Exception {
        String url = "http://example.com/api";
        String jsonString = "{\"key\":\"value\"}";
        byte[] bytes = {0x01, 0x02, 0x03};
        String response = sendPostRequest(url, jsonString, bytes);
        System.out.println(response);
    }

    private static String sendPostRequest(String urlString, String jsonString, byte[] bytes) throws IOException {
        URL url = new URL(urlString);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "application/json");
        conn.setDoOutput(true);

        DataOutputStream out = new DataOutputStream(conn.getOutputStream());
        out.writeBytes(jsonString);
        out.flush();
        out.close();

        InputStream inputStream = conn.getInputStream();
        BufferedReader in = new BufferedReader(new InputStreamReader(inputStream));
        String inputLine;
        StringBuilder response = new StringBuilder();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        return response.toString();
    }
}

在这个例子中，我们使用了HttpURLConnection来发送POST请求。我们设置了请求头Content-Type为application/json，然后使用DataOutputStream将json字符串写入请求体。字节流也可以使用同样的方式写入请求体。最后，我们从连接的输入流中读取响应内容。