用JAVA代码编写HttpURLConnection 发送get和post请求的方法

下面是使用 Java 代码编写 HttpURLConnection 发送 GET 和 POST 请求的示例：

1. 发送 GET 请求

import java.net.*;
import java.io.*;

public class HttpGet {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://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 (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2. 发送 POST 请求

import java.net.*;
import java.io.*;

public class HttpPost {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://example.com");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-Type", "application/json");
            conn.setRequestProperty("Accept", "application/json");
            conn.setDoOutput(true);

            String input = "{\"username\":\"test\",\"password\":\"test\"}";

            OutputStream os = conn.getOutputStream();
            os.write(input.getBytes());
            os.flush();

            if (conn.getResponseCode() != HttpURLConnection.HTTP_CREATED) {
                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 (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

注意，在发送 POST 请求时需要设置 `Content-Type` 和向输出流中写入请求体。如果需要发送其他类型的请求，可以根据需要修改 `setRequestMethod` 和请求头部。