java post请求带请求头

好的，下面是Java中带请求头的POST请求示例代码：

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

public class HttpPostWithHeaderExample {

    public static void main(String[] args) throws Exception {
        String url = "http://example.com/api";
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // 设置请求方法为POST
        con.setRequestMethod("POST");

        // 设置请求头
        con.setRequestProperty("User-Agent", "Mozilla/5.0");
        con.setRequestProperty("Content-Type", "application/json");

        // 设置POST请求体
        String postBody = "{\"name\":\"John\", \"age\":30}";
        con.setDoOutput(true);
        con.getOutputStream().write(postBody.getBytes("UTF-8"));

        // 发送POST请求
        int responseCode = con.getResponseCode();
        System.out.println("Sending 'POST' request to URL : " + url);
        System.out.println("Response Code : " + responseCode);

        // 读取响应内容
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        // 打印响应内容
        System.out.println(response.toString());
    }
}

在上面的代码中，我们首先创建一个URL对象，并打开一个HttpURLConnection连接。然后，我们设置请求方法为POST，并设置请求头。接下来，我们设置POST请求体，并发送POST请求。最后，我们读取响应内容并打印出来。