如何将文件写入HTTP请求Java

import java.io.*;
import java.net.*;

public class FileUploadExample {
    public static void main(String[] args) {
        String fileToUpload = "path/to/file.txt";
        String uploadUrl = "http://example.com/upload";

        try {
            // 创建URL对象
            URL url = new URL(uploadUrl);

            // 打开连接
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            // 设置请求方法为POST
            connection.setRequestMethod("POST");

            // 允许输入输出流
            connection.setDoInput(true);
            connection.setDoOutput(true);

            // 设置请求头信息
            connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW");

            // 创建输出流
            OutputStream outputStream = connection.getOutputStream();
            PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream, "UTF-8"), true);

            // 写入文件数据
            File file = new File(fileToUpload);
            FileInputStream fileInputStream = new FileInputStream(file);
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            // 结束请求
            writer.flush();
            writer.close();

            // 获取响应结果
            int responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                // 处理成功上传的响应结果
                InputStream inputStream = connection.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
                String line;
                StringBuilder response = new StringBuilder();
                while ((line = reader.readLine()) != null) {
                    response.append(line);
                }
                reader.close();
                System.out.println("上传成功！响应结果：" + response.toString());
            } else {
                // 处理上传失败的情况
                System.out.println("上传失败，错误代码：" + responseCode);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}