网络编程问题探究：Java HTTP客户端如何向服务器发送请求？

原创 ╰+哭是因爲堅強的太久メ 2024-11-22 05:00 11阅读 0赞

在Java中，我们可以使用java.net.URL或者java.io.HttpURLConnection来向服务器发送HTTP请求。

1. 使用URL和HttpURLConnection：

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

public class HttpClientExample {
    public static void main(String[] args) throws Exception {
        // 1. URL方式
        String urlStr = "http://example.com";
        URL url = new URL(urlStr);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        
        // 设置请求方法
        conn.setRequestMethod("GET");
        
        // 获取响应状态码
        int responseCode = conn.getResponseCode();
        System.out.println("Response Code: " + responseCode);
        
        // 处理响应数据
        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()))); 
        String output;
        while ((output = br.readLine()) != null) {
            System.out.println(output);
        }
        br.close();
    }
}
```

2. 使用第三方库如Apache HttpClient：

```java
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class ApacheHttpClientExample {
    public static void main(String[] args) throws Exception {
        // 创建HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();

// 使用HttpGet构建请求对象
        HttpGet httpGet = new HttpGet("http://example.com");
        
        // 执行请求，获取响应实体
        CloseableHttpResponse response = httpClient.execute(httpGet);
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            System.out.println("Response Entity: " + entity.toString()));
            entity.consumeContent();  // 必须调用此方法，否则缓存内容会被丢弃
        }
        
        // 关闭资源
        response.close();
        httpClient.close();
    }
}
```

以上两种方式都可以实现向服务器发送HTTP请求。