java代码http请求

以下是Java中发送HTTP请求的两种方式：

1.使用HttpURLConnection发送HTTP请求

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

public class HttpURLConnectionExample {

    public static void main(String[] args) {
        try {
            URL url = new URL("http://www.example.com");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Accept", "application/json");

            if (conn.getResponseCode() != 200) {
                throw new RuntimeException("Failed : HTTP error code : "
                        + conn.getResponseCode());
            }

            BufferedReader br = new BufferedReader(new InputStreamReader(
                    (conn.getInputStream())));

            String output;
            System.out.println("Output from Server .... \n");
            while ((output = br.readLine()) != null) {
                System.out.println(output);
            }

            conn.disconnect();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

2.使用HttpClient发送HTTP请求

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClientBuilder;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class HttpClientExample {

    public static void main(String[] args) {
        try {
            HttpClient client = HttpClientBuilder.create().build();
            HttpGet request = new HttpGet("http://www.example.com");
            request.addHeader("User-Agent", "Mozilla/5.0");
            HttpResponse response = client.execute(request);

            BufferedReader rd = new BufferedReader(
                    new InputStreamReader(response.getEntity().getContent()));

            StringBuffer result = new StringBuffer();
            String line = "";
            while ((line = rd.readLine()) != null) {
                result.append(line);
            }

            System.out.println(result.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}