java post请求代码

以下是一个Java中使用HttpURLConnection发送POST请求的示例代码：

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

public class HttpPostExample {
    private final String USER_AGENT = "Mozilla/5.0";

    public static void main(String[] args) throws Exception {
        HttpPostExample http = new HttpPostExample();

        System.out.println("Sending HTTP POST request");
        String url = "http://www.example.com/api";
        String params = "name=John&age=30";
        String response = http.sendPost(url, params);
        System.out.println("Response from server:\n" + response);
    }

    // HTTP POST request
    private String sendPost(String url, String params) throws Exception {
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // Add request header
        con.setRequestMethod("POST");
        con.setRequestProperty("User-Agent", USER_AGENT);
        con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

        // Send post request
        con.setDoOutput(true);
        DataOutputStream wr = new DataOutputStream(con.getOutputStream());
        wr.writeBytes(params);
        wr.flush();
        wr.close();

        // Read response from server
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        return response.toString();
    }
}

在此示例中，我们通过HttpURLConnection发送了一个POST请求。我们设置了请求头，设置请求方法为POST，并将参数作为请求体发送。我们还从服务器读取了响应并将其作为字符串返回。