用Java写一个http工具类

以下是一个简单的Java HTTP工具类，可以发送GET和POST请求并返回响应信息：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Map;

public class HttpUtil {

    public static String sendGet(String url, Map<String, String> params) throws Exception {
        StringBuilder result = new StringBuilder();
        String encodedUrl = url;
        if (params != null) {
            encodedUrl += "?";
            for (Map.Entry<String, String> entry : params.entrySet()) {
                encodedUrl += URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + URLEncoder.encode(entry.getValue(), "UTF-8") + "&";
            }
            encodedUrl = encodedUrl.substring(0, encodedUrl.length() - 1);
        }
        URL obj = new URL(encodedUrl);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        con.setRequestMethod("GET");

        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        while ((inputLine = in.readLine()) != null) {
            result.append(inputLine);
        }
        in.close();

        return result.toString();
    }

    public static String sendPost(String url, Map<String, String> params) throws Exception {
        StringBuilder result = new StringBuilder();
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        con.setRequestMethod("POST");
        con.setDoOutput(true);

        StringBuilder postData = new StringBuilder();
        if (params != null) {
            for (Map.Entry<String, String> entry : params.entrySet()) {
                if (postData.length() != 0) {
                    postData.append("&");
                }
                postData.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
                postData.append("=");
                postData.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
            }
        }
        byte[] postDataBytes = postData.toString().getBytes("UTF-8");
        con.getOutputStream().write(postDataBytes);

        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        while ((inputLine = in.readLine()) != null) {
            result.append(inputLine);
        }
        in.close();

        return result.toString();
    }
}

使用方法：

发送GET请求：

String url = "https://www.example.com";
Map<String, String> params = new HashMap<>();
params.put("param1", "value1");
params.put("param2", "value2");
String response = HttpUtil.sendGet(url, params);
System.out.println(response);

发送POST请求：

String url = "https://www.example.com";
Map<String, String> params = new HashMap<>();
params.put("param1", "value1");
params.put("param2", "value2");
String response = HttpUtil.sendPost(url, params);
System.out.println(response);