java http请求发送文件流

以下是Java发送文件流的示例代码：

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

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

        try {
            URL url = new URL(urlStr);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setDoOutput(true);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW");

            OutputStream outputStream = conn.getOutputStream();
            PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream, "UTF-8"), true);

            writer.append("------WebKitFormBoundary7MA4YWxkTrZu0gW\r\n");
            writer.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + fileName + "\"\r\n");
            writer.append("Content-Type: text/plain\r\n\r\n");

            FileInputStream inputStream = new FileInputStream(file);
            byte[] buffer = new byte[4096];
            int bytesRead = -1;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
            outputStream.flush();
            inputStream.close();

            writer.append("\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW--\r\n");
            writer.close();

            int responseCode = conn.getResponseCode();
            System.out.println("Response Code: " + responseCode);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

该示例代码使用Java的HttpURLConnection类发送HTTP POST请求，并将文件流作为请求体发送到指定的URL。在示例代码中，需要将`urlStr`变量设置为目标URL，`file`变量设置为要上传的文件路径，`fileName`变量设置为要上传的文件名。在实际应用中，需要根据具体情况进行修改。