网络编程问题：Java如何实现HTTP请求和响应

原创心已赠人 2024-09-15 20:12 103阅读 0赞

在Java中，我们可以使用两个主要的库来实现HTTP请求和响应：`java.net.HttpURLConnection` 和 `org.apache.http.client.methods.HttpRequestBase`。

1. 使用`HttpURLConnection`：
```java
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpURLConnectionExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://example.com");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

// Set method (GET, POST, etc.)
        connection.setRequestMethod("GET");

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

// If response code is 200 (OK),
        // read the response body
        if (responseCode == 200) {
            InputStream inputStream = connection.getInputStream();
            byte[] buffer = new byte[1024];
            while (true) {
                int bytesRead = inputStream.read(buffer);
                if (bytesRead < 0) {
                    break; // reached end of stream
                }
                // process the buffer data here
            }

inputStream.close(); // close input stream
        }

connection.disconnect(); // disconnect from server
    }
}
```

2. 使用`HttpClient`：
如果你使用的是Apache HttpClient，你可以创建一个`HttpRequestBase`的子类来实现HTTP请求。以下是一个示例：

```java
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;

public class HttpClientExample {
    public static void main(String[] args) throws Exception {
        // 创建一个POST请求
        HttpPost httpPost = new HttpPost("http://example.com/api");

// 添加HTTP实体（在这种情况下是字符串内容）
        StringEntity stringEntity = new StringEntity("Hello, World!");
        httpPost.setEntity(stringEntity);

// 发送请求并获取响应
        CloseableHttpResponse response =HttpClientUtils.executeHttpClient(httpPost);
        if(response.getStatusLine().getStatusCode() == 200){
            HttpEntity entity = response.getEntity();
            System.out.println(new String(entity.getContent())));
        }
        response.close(); // 关闭响应对象
    }
}
```

注意：Apache HttpClient库已在Java 8及更高版本中移除，建议使用`java.net.HttpURLConnection`或第三方HTTP客户端库（如OkHttp）。