如何在Java中使用URLConnection Java发送网络请求的方式

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

public class UrlConnectionGetExample {

    public static void main(String[] args) {
        try {
            URL url = new URL("https://jsonplaceholder.typicode.com/posts/1"); // 示例URL
            HttpURLConnection connection = (null); // 类型转换是必要的
            connection.setRequestMethod("GET"); // 设置请求方法为GET
            connection.setRequestProperty("User-Agent", "Mozilla/5.0"); // 模拟浏览器User-Agent

            // 设置连接和读取超时，避免长时间等待
            connection.setConnectTimeout(5000); // 5秒连接超时
            connection.setReadTimeout(8000); // 8秒读取超时

            int responseCode = connection.getResponseCode();
            System.out.println("GET Response Code :: " + responseCode);

            if (responseCode == HttpURLConnection.HTTP_OK) { // 检查HTTP响应码
                BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String inputLine;
                StringBuffer response = new StringBuffer();

                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                in.close(); // 确保流被关闭

                System.out.println(response.toString());
            } else {
                System.out.println("GET request not worked");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 在实际应用中，这里应该确保connection被断开，虽然通常JVM会处理
            // connection.disconnect(); // 显式断开连接，释放资源
        }
    }
}

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;

public class UrlConnectionPostExample {

    public static void main(String[] args) {
        try {
            URL url = new URL("https://jsonplaceholder.typicode.com/posts"); // 示例POST URL
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setRequestProperty("User-Agent", "Mozilla/5.0");
            connection.setRequestProperty("Content-Type", "application/json"); // 假设发送JSON数据
            connection.setDoOutput(true); // 允许写入请求体

            String jsonInputString = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
            byte[] postData = jsonInputString.getBytes(StandardCharsets.UTF_8);

            try (DataOutputStream wr = new DataOutputStream(connection.getOutputStream())) {
                wr.write(postData);
                wr.flush();
            } // try-with-resources 会自动关闭流

            int responseCode = connection.getResponseCode();
            System.out.println("POST Response Code :: " + responseCode);

            if (responseCode == HttpURLConnection.HTTP_CREATED || responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String inputLine;
                StringBuffer response = new StringBuffer();

                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                in.close();
                System.out.println(response.toString());
            } else {
                System.out.println("POST request not worked, Response Code: " + responseCode);
            }

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

// 仅用于测试！严重不推荐在生产环境中使用！
public static void disableSslVerification() {
    try {
        // 创建一个不验证任何证书的TrustManager
        TrustManager[] trustAllCerts = new TrustManager[]{
            new X509TrustManager() {
                public X509Certificate[] getAcceptedIssuers() {
                    return null;
                }
                public void checkClientTrusted(X509Certificate[] certs, String authType) {
                }
                public void checkServerTrusted(X509Certificate[] certs, String authType) {
                }
            }
        };

        // 获取SSLContext实例
        SSLContext sc = SSLContext.getInstance("TLS");
        sc.init(null, trustAllCerts, new java.security.SecureRandom());
        HttpsURLConnection.setDefaultSSLContext(sc);

        // 创建一个不验证任何主机名的HostnameVerifier
        HostnameVerifier allHostsValid = new HostnameVerifier() {
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        };
        HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

// 示例：使用try-with-resources确保流关闭
try {
    URL url = new URL("http://example.com");
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    // ... 设置请求方法、属性等

    int responseCode = connection.getResponseCode();
    if (responseCode == HttpURLConnection.HTTP_OK) {
        try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
            String inputLine;
            StringBuffer response = new StringBuffer();
            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            System.out.println(response.toString());
        } // in 会在这里自动关闭
    }
    // ...
} catch (Exception e) {
    e.printStackTrace();
} finally {
    // 确保连接断开，释放资源
    if (connection != null) {
        connection.disconnect();
    }
}