在Java中获取HTTP请求

在Java中获取HTTP请求的方式取决于你使用的框架或环境,以下是几种常见场景下的方法：

在Servlet环境中获取

在Java Web应用（Servlet）中，可以通过HttpServletRequest对象获取请求信息：

protected void doGet(HttpServletRequest request, HttpServletResponse response) {
    // 获取请求方法
    String method = request.getMethod();
    // 获取请求URI
    String uri = request.getRequestURI();
    // 获取请求参数
    String param = request.getParameter("paramName");
    // 获取请求头
    String headerValue = request.getHeader("User-Agent");
    // 获取请求体
    BufferedReader reader = request.getReader();
    String line;
    StringBuilder requestBody = new StringBuilder();
    while ((line = reader.readLine()) != null) {
        requestBody.append(line);
    }
}

在Spring Boot中获取

在Spring Boot中,可以通过多种方式获取HTTP请求：

通过依赖注入

@RestController
public class MyController {
    @GetMapping("/example")
    public String example(HttpServletRequest request) {
        // 使用request对象
        return request.getRequestURI();
    }
}

通过注解获取特定部分

@GetMapping("/example")
public String example(
    @RequestParam String name,  // 获取请求参数
    @RequestHeader("User-Agent") String userAgent,  // 获取请求头
    @RequestBody String body  // 获取请求体
) {
    return name + " - " + userAgent + " - " + body;
}

使用Java原生HttpURLConnection

如果你需要手动发送HTTP请求并获取响应：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpRequestExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://example.com");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        // 设置请求方法
        connection.setRequestMethod("GET");
        // 获取响应码
        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);
        // 读取响应内容
        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());
    }
}

使用第三方库

使用Apache HttpClient

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;
import org.apache.http.util.EntityUtils;
public class HttpClientExample {
    public static void main(String[] args) throws Exception {
        try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
            HttpGet request = new HttpGet("https://example.com");
            try (CloseableHttpResponse response = httpClient.execute(request)) {
                String result = EntityUtils.toString(response.getEntity());
                System.out.println(result);
            }
        }
    }
}

使用OkHttp

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
public class OkHttpExample {
    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url("https://example.com")
                .build();
        try (Response response = client.newCall(request).execute()) {
            System.out.println(response.body().string());
        }
    }
}

选择哪种方法取决于你的具体需求和应用场景，在Web应用中，通常使用框架提供的方法（如Spring的HttpServletRequest），而在需要手动发送HTTP请求时,可以使用原生Java或第三方库。