java http请求工具类

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

public class HttpUtil {

    // 发送GET请求
    public static String sendGet(String urlString) {
        StringBuilder result = new StringBuilder();
        try {
            URL url = new URL(urlString);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");

            // 设置连接和读取超时时间
            connection.setConnectTimeout(5000);
            connection.setReadTimeout(5000);

            // 获取响应码
            int responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                while ((line = in.readLine()) != null) {
                    result.append(line);
                }
                in.close();
            } else {
                System.out.println("GET request failed with response code: " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result.toString();
    }

    // 发送POST请求
    public static String sendPost(String urlString, String postData) {
        StringBuilder result = new StringBuilder();
        try {
            URL url = new URL(urlString);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);

            // 设置连接和读取超时时间
            connection.setConnectTimeout(5000);
            connection.setReadTimeout(5000);

            // 写入POST数据
            try (OutputStream os = connection.getOutputStream()) {
                byte[] input = postData.getBytes("utf-8");
                os.write(input, 0, input.length);
            }

            // 获取响应码
            int responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                while ((line = in.readLine()) != null) {
                    result.append(line);
                }
                in.close();
            } else {
                System.out.println("POST request failed with response code: " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result.toString();
    }
}

解释说明：

1. sendGet 方法：用于发送 GET 请求。它接受一个 URL 字符串作为参数，并返回服务器响应的字符串。如果请求成功（HTTP 状态码为 200），则读取并返回响应内容；否则，输出错误信息。

2. sendPost 方法：用于发送 POST 请求。它接受两个参数：URL 字符串和要发送的 POST 数据。该方法将 POST 数据写入请求体中，并返回服务器的响应内容。同样地，如果请求成功，则读取并返回响应内容；否则，输出错误信息。

3. 超时设置：为了防止请求长时间无响应，代码中设置了连接超时（5秒）和读取超时（5秒）。

4. 异常处理：通过 try-catch 块捕获可能发生的异常，并打印堆栈信息以便调试。