Java 中 HTTP 响应如何处理

在 Java 中处理 HTTP 响应，通常需要使用 Java 网络编程库，如 java.net.HttpURLConnection 或第三方库，如 Apache HttpClient 或 OkHttp

1. 使用 HttpURLConnection（适用于简单的 HTTP 请求）：

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

public class HttpResponseExample {
    public static void main(String[] args) {
        try {
            String apiUrl = "https://api.example.com/data"; // 替换为您要请求的 URL
            URL url = new URL(apiUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setRequestProperty("User-Agent", "Mozilla/5.0");
            connection.setRequestProperty("Accept", "application/json");

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

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

                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                in.close();

                System.out.println("Response: " + response.toString());
            } else {
                System.out.println("GET request failed");
            }

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

2. 使用 Apache HttpClient（适用于更复杂的 HTTP 请求）：

首先，您需要添加 Apache HttpClient 库依赖。如果您使用 Maven，可以在 pom.xml 文件中添加以下依赖：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>

然后，您可以使用以下代码处理 HTTP 响应：

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpResponseExample {
    public static void main(String[] args) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String apiUrl = "https://api.example.com/data"; // 替换为您要请求的 URL
        HttpGet httpGet = new HttpGet(apiUrl);

        try {
            HttpResponse httpResponse = httpClient.execute(httpGet);
            int responseCode = httpResponse.getStatusLine().getStatusCode();
            System.out.println("Response Code: " + responseCode);

            if (responseCode == 200) {
                HttpEntity httpEntity = httpResponse.getEntity();
                String response = EntityUtils.toString(httpEntity);
                System.out.println("Response: " + response);
            } else {
                System.out.println("GET request failed");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                httpClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

这些示例展示了如何使用 Java 处理 HTTP 响应。根据您的需求，您可能需要解析 JSON 数据、处理重定向或设置超时等。这些库提供了丰富的功能，可以帮助您轻松处理各种 HTTP 请求和响应。