如何在Java中实现HTTP请求，包括GET和POST方法

原创 ╰半夏微凉° 2024-09-27 06:18 40阅读 0赞

在Java中，我们可以使用许多库来发送HTTP请求。这里我将使用两个常用的库：HttpURLConnection和Apache HttpClient。

1. 使用HttpURLConnection：

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

public class HttpURLConnectionExample {
    public static void main(String[] args) {
        String urlStr = "https://example.com"; // Replace with your URL

try {
            URL url = new URL(urlStr);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

// Set request method
            if ("GET".equals(connection.getRequestMethod()))) {
                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()); // Print the response
            } else if ("POST".equals(connection.getRequestMethod()))) { // Handle POST request
                String data = "This is a sample data for POST request"; // Replace with your data

connection.setDoOutput(true);

DataOutputStream out = new DataOutputStream(connection.getOutputStream()));

out.writeBytes(data); // Write the data to the output stream

out.flush(); // Flush the output buffer

out.close();
                connection.disconnect();

// Print response if available
                System.out.println("POST Response: " + getResponse(connection, connection.getResponseCode()))); // Print the response
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

private static String getResponse(HttpURLConnection connection, int statusCode) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())));

StringBuilder responseBuilder = new StringBuilder();

String inputLine;
        while ((inputLine = in.readLine()) != null)) {
            responseBuilder.append(inputLine);
        }

in.close();
        if (statusCode >= 200 && statusCode < 300) { // Successful request
            return responseBuilder.toString();
        } else { // Error status code
            throw new RuntimeException("Error occurred with status code " + statusCode + ". Response: " + responseBuilder.toString()));
        }
    }
}
```

这个例子展示了如何使用HttpURLConnection发送GET和POST请求。注意，Apache HttpClient库也可以用来发送HTTP请求，但这里我只提供了HttpURLConnection的示例。